ISCHEMIA 1.1 Ischemic Stroke A 77-year-old woman presented with the sudden onset of left-sided weakness and numbness. On examination, in addition to the weakness and sensory loss, she had a left homonymous hemianopsia and was unaware of her deficits, denying that there was anything wrong with her. Her eyes were deviated to the right. Images 1.1A–1.1C: Diffusion-weighted axial images demonstrate infarction in the territory of the right middle cerebral artery (MCA). Image 1.1D: Gross picture of a subacute right MCA infarction. Images 1.1E and 1.1F: Normal magnetic resonance (MR) angiogram of the neck and head demonstrates the intracranial and extracranial vasculature. Images 1.1G and 1.1H: Normal magnetic resonance angiographies of the head demonstrate the intracranial vasculature. Image 1.1I: Normal CT angiogram of the head demonstrates the circle of Willis. Image 1.1J: Illustration of the cortical vascular territories (image credit Dr. Frank Gaillard). Images 1.1K and 1.1L: Catheter angiography of the internal carotid artery (ICA) and vertebral artery demonstrates normal intracranial vasculature. Images 1.1M–1.1P: Diffusion-weighted axial images demonstrate an acute infarction in the territory of the left ACA. Image 1.1Q: Diffusion-weighted axial image demonstrates an acute infarction in the superior division of the MCA. Image 1.1R: Diffusion-weighted axial image demonstrates an acute infarction in the inferior division of the MCA. Image 1.1S: Diffusion-weighted axial image demonstrates an acute infarction of the deep branches of the MCA. Images 1.1T and 1.1U: Diffusion-weighted axial images demonstrate an acute infarction of the left posterior cerebral artery (PCA). Images 1.1V and 1.1W: Diffusion-weighted axial images demonstrate an acute infarction of the right MCA and PCA. Image 1.1X: CT angiogram demonstrates a fetal PCA (red arrow) on the right. A normal PCA is seen on the left (blue arrow). Image 1.1Y: Axial CT image demonstrates a dense right MCA (red arrow). Image 1.1Z: Axial CT image demonstrates blurring of the gray–white junction on the right (red arrow). Images 1.1AA and 1.1BB: Axial CT images demonstrate hypodensity in the MCA territory on the right with midline shift and compression of the lateral ventricle. Images 1.1CC–1.1EE: CT perfusion images demonstrate an acute right MCA infarction. In this case, the ischemic core is delineated by the red circle while the penumbra is delineated by the white oval. Images 1.1FF and 1.1GG: Diffusion-weighted axial image and apparent diffusion coefficient map demonstrate restricted diffusion in the territory of the right MCA infarct. Image 1.1HH: Magnetic resonance angiogram demonstrates occlusion of the right MCA (red arrow). The normal MCA is seen (blue arrow). Images 1.1II and 1.1JJ: Catheter angiogram of a patient with a large MCA infarction shows loss of flow in the MCA (red arrow). Some flow is restored in the occluded artery after removal of the thrombus. Image 1.1KK: Axial CT image demonstrates a large right MCA infarction with significant right to left midline shift. Image 1.1LL: Axial CT image from the same patient after a right hemicraniectomy demonstrates partial resolution of the mass effect. Images 1.1MM and 1.1NN: Catheter angiogram demonstrates significant stenosis of the ICA (red arrow). The ICA is shown after the placement of a stent (blue arrow). Image 1.1OO: EKG of atrial fibrillation (top) and normal sinus rhythm (bottom). The purple arrow indicates a P wave, which is lost in atrial fibrillation (image credit J. Heuser). Table 1.1.1 Antiplatelet Agents Images 1.1PP and 1.1QQ: Coronal T1-weighed and axial fluid-attenuated inversion recovery (FLAIR) images demonstrate an old infarct in the right MCA territory. There is corresponding dilation of the lateral ventricle adjacent to the infarct (red arrow). Image 1.1RR: Axial T1-weighted image demonstrates an old infarction in the right posterior MCA and PCA territories. Image 1.1SS: Axial T1-weighted image from the same patient demonstrates atrophy of the right cerebral peduncle (red arrow) due to Wallerian degeneration. Images 1.1TT and 1.1UU: Gross pathology demonstrates an old right MCA infarction and resultant atrophy of the pons. 1. Berkhemer OA, Fransen PS, Beumer D, et al. A randomized trial of intraarterial treatment for acute ischemic stroke. N Engl J Med. January 2015;372(1):11–20. 2. Powers WJ, Derdeyn CP, Biller J, et al. 2015 American Heart Association/American Stroke Association focused update of the 2013 guidelines for the early management of patients with acute ischemic stroke regarding endovascular treatment: A guideline for healthcare professionals from the American Heart Association/American Stroke Association. Stroke. October 2015;46(10):3020–3035. 3. Jauch EC, Saver JL, Adams HP Jr, et al. Guidelines for the early management of patients with acute ischemic stroke: a guideline for healthcare professionals from the American Heart Association/American Stroke Association. Stroke. March 2013;44(3):870–947. Unless otherwise stated, all pathology images in this chapter are from the website http://medicine.stonybrookmedicine.edu/pathology/neuropathology and are reproduced with permission of the author, Roberta J. Seidman, MD, Associate Professor. Unauthorized reproduction is prohibited. 1.2 Brainstem Stroke Syndromes A 66-year-old man presented with the acute onset of double vision imbalance. On examination, he had a left abducens nerve palsy and ataxia of his left arm. He had some mild weakness of his right side. Image 1.2A: Diffusion-weighted axial image demonstrates an infarction of the medial pons. Illustration 1.2.1: Vascular supply to the brainstem (Blausen.com staff. “Blausen gallery 2014.” Wikiversity Journal of Medicine). Image 1.2B: Diffusion-weighted axial image demonstrates an infarction of the left cerebral peduncle of the midbrain in a patient who presented with an ipsilateral oculomotor palsy and contralateral weakness (Weber’s syndrome). Image 1.2C: Diffusion-weighted axial image demonstrates an infarction of the left midbrain affecting both the red nucleus and the cerebral peduncle in a patient who presented with a left oculomotor nerve palsy as well as contralateral weakness and ataxia (Claude’s syndrome). Image 1.2D: Diffusion-weighted axial image demonstrates an infarction of the left paramedian midbrain in a patient who presented with a left oculomotor palsy, contralateral ataxia, and mild contralateral weakness (Benedikt’s syndrome). Image 1.2E: Diffusion-weighted axial image demonstrates an infarction of the right lateral medulla (red arrow). Image 1.2F: MR angiogram demonstrates absence of flow in the basilar artery (red arrow). Image 1.2G: Diffusion-weighted axial image demonstrates restricted diffusion of the entire pons. Image 1.2H: Diffusion-weighted axial image demonstrates restricted diffusion of the bilateral rostral midbrain, the “V sign.” Image 1.2I: Diffusion-weighted axial image demonstrates bilateral paramedian thalamic infarctions. 1.3 Cerebellar Strokes A 30-year-old male presented with an acute onset of nausea, vertigo, and ataxia. On examination, he had Horner’s syndrome on the left and was unable to walk due to his imbalance. Images 1.3A–1.3D: Axial-diffusion-weighted images demonstrate an acute infarct of the left posterior inferior cerebellar artery. Images 1.3E and 1.3F: Catheter angiogram demonstrating normal vasculature of the posterior circulation. Image 1.3G: Axial diffusion-weighted image demonstrates an acute infarction (red arrow) of the right anterior inferior cerebellar artery. Image 1.3H: Axial diffusion-weighted image demonstrates an acute infarction of the left superior cerebellar artery. 1. Erdemoglu AK, Duman T. Superior cerebellar artery territory stroke. Acta Neurol Scand. October 1998;98(4):283–287. 2. Montgomery AK, Maixner WJ, Wallace D, Wray A, Mackay MT. Decompressive craniectomy in childhood posterior circulation stroke: a case series and review of the literature. Pediatr Neurol. September 2012;47(3):193–197. 3. Tsitsopoulos PP, Tobieson L, Enblad P, Marklund N. Surgical treatment of patients with unilateral cerebellar infarcts: clinical outcome and prognostic factors. Acta Neurochir (Wien). October 2011;153(10):2075–2083. 4. Nouh A, Remke J, Ruland S. Ischemic posterior circulation stroke: a review of anatomy, clinical presentations, diagnosis, and current management. Front Neurol. April 2014;5:30. 1.4 Lacunar Strokes A 60-year-old smoker with uncontrolled hypertension presented with the acute onset of numbness of his left arm and leg. On exam, he had decreased sensation to all sensory modalities on the entire left side, including his face. Image 1.4A: Diffusion-weighted axial image reveals an area of restricted diffusion in the right thalamus. Images 1.4B–1.4G: Lacunar strokes in common locations are seen on the axial-diffusion-weighted images. These are: the subcortical white matter (1.4B), cerebellum (1.4C), the thalamus (1.4D), the pons (1.4E), the internal capsule (1.4F), and the basal ganglia (1.4G). 1. Caplan LR. Lacunar infarction and small vessel disease: pathology and pathophysiology. J Stroke. January 2015;17(1):2–6. 2. Mok V, Kim JS. Prevention and management of cerebral small vessel disease. J Stroke. May 2015;17(2):111–122. 3. Norrving B. Lacunar infarcts: no black holes in the brain are benign. Pract Neurol. August 2008;8(4):222–228. 4. Pantoni L, Fierini F, Poggesi A. Thrombolysis in acute stroke patients with cerebral small vessel disease. Cerebrovasc Dis. 2014;37(1):5–13. 1.5 Watershed Strokes A 76-year-old man with hypertension and diabetes underwent a coronary bypass artery graft that was complicated by severe blood loss. When he awoke, he was unable to move his proximal right arm and would not speak unless he became upset. Images 1.5A–1.5D: Diffusion-weighted axial images demonstrate a subcortical, watershed infarction on the left. 1. Cortical or outer infarctions occur in the border zones between the MCA/ACA or MCA/PCA. These are thought to be due primarily to microemboli. 2. Internal or subcortical infarctions occur in the white matter adjacent to the lateral ventricles, between the deep and the superficial vessels of the MCA, or between the superficial systems of the MCA and ACA. These are thought to be due to hypotension or severe carotid stenosis. Images 1.5E and 1.5F: Diffusion-weighted axial images demonstrate restricted diffusion in the parafalcine subcortical white matter. Images 1.5G–1.5I: Diffusion-weighted axial images demonstrate cortical watershed infarctions between the ACA and MCA (red arrows) bilaterally and the PCA and MCA (yellow arrows), as well as extensive subcortical, watershed infarctions (blue arrows). Image 1.5J: Gross pathology demonstrates recent bilateral watershed infarction, in the territories supplied by the distal branches of the anterior and middle cerebral arteries. 1. D’Amore C, Paciaroni M. Border-zone and watershed infarctions. Front Neurol Neurosci. 2012;30:181–184. Unless otherwise stated, all pathology images in this chapter are from the website http://medicine.stonybrookmedicine.edu/pathology/neuropathology and are reproduced with permission of the author, Roberta J. Seidman, MD, Associate Professor. Unauthorized reproduction is prohibited. 1.6 Hypoxic/Ischemic Injury A 76-year-old man was found down at home. On examination, he had a gag reflex and minimally reactive pupils, but no evidence of any other neurological function. Images 1.6A and 1.6B: Axial CT images demonstrate global cerebral edema evidenced by the loss of distinction between the gray and white matter. There is sulcal effacement, bilateral uncal herniation, diffuse compression of the entire ventricular system, and complete effacement of the basal cisterns. Hyperdensity of the cerebellum (red arrow) is termed the “reversal sign.” Images 1.6C and 1.6D: Axial FLAIR image and CT show hyperintensity and hypodensity of the caudate head (yellow arrow) and putamen (red arrow). Images 1.6E and 1.6F: Axial diffusion weighted images (DWIs) demonstrate restricted diffusion of the basal ganglia and cortical ribbon. Image 1.6G: Gross pathology demonstrates thinning of the majority of the cortical ribbon and atrophy of the deep gray structures. 1. Arrich J, Holzer M, Havel C, Müllner M, Herkner H. Hypothermia for neuroprotection in adults after cardiopulmonary resuscitation. Cochrane Database Syst Rev. September 2012;9:CD004128. 2. Greer DM, Scripko PD, Wu O, et al. Hippocampal magnetic resonance imaging abnormalities in cardiac arrest are associated with poor outcome. J Stroke Cerebrovasc Dis. October 2013;22(7):899–905. 3. Greer D, Scripko P, Bartscher J, et al. Clinical MRI interpretation for outcome prediction in cardiac arrest. Neurocrit Care. October 2012;17(2):240–244. Unless otherwise stated, all pathology images in this chapter are from the website http://medicine.stonybrookmedicine.edu/pathology/neuropathology and are reproduced with permission of the author, Roberta J. Seidman, MD, Associate Professor. Unauthorized reproduction is prohibited. 1.7 Sinus Venous Thrombosis A 34-year-old woman presented with an acute onset of left-side weakness and lethargy. She had a severe headache for the past week, but had not sought medical attention. In addition to her weakness, fundoscopic examination revealed papilledema. Images 1.7A and 1.7B: Axial CT images demonstrate hyperdensity in the left transverse sinus (red arrow), the superior sagittal sinus, and a cortical vein (yellow arrow). Image 1.7C: An MR venogram from the same patient reveals extensive thrombosis (absence of flow) in the left transverse sinus (blue arrow) and superior sagittal sinus (green arrow). Image 1.7D: Pathological specimen of a thrombosed superior sagittal sinus. Table 1.7.1 Venous Drainage of the Brain Sinus Drains to Inferior sagittal sinus Straight sinus Superior sagittal sinus Right transverse sinus Straight sinus Left transverse sinus Occipital sinus Confluence of sinuses Sphenoparietal sinus/superior ophthalmic vein Cavernous sinuses Cavernous sinuses Superior and inferior petrosal sinuses Superior petrosal sinus Transverse sinuses Transverse sinuses Sigmoid sinus Inferior petrosal sinus Sigmoid sinus Sigmoid sinuses Internal jugular vein Image 1.7E: Normal MR venogram. Images 1.7F and 1.7G: MR venogram demonstrates absence of flow in the superior sagittal sinus (red arrows) and transverse sinus (yellow arrow) on the left, consistent with clot within the lumen of the vein. Image 1.7H: Postcontrast axial T1-weighted image demonstrates absence of flow in the superior sagittal sinus (red arrow), the “empty-delta sign.” Image 1.7I: Diffusion-weighted axial image demonstrates a left basal ganglia and bithalamic infarcts. Image 1.7J: MR venogram demonstrates absence of flow in the deep venous system (red arrow). Images 1.7K and 1.7L: Axial CT images demonstrate hyperdensity of the inferior sagittal sinus (red arrow) and confluence of sinuses (yellow arrow). Images 1.7M and 1.7N: Axial and sagittal FLAIR images demonstrate severe, bilateral white matter disease in a patient with superior sagittal sinus thrombosis. Image 1.7O: CT image demonstrates hemorrhage in the left frontal lobe. Image 1.7P: Gross pathology demonstrates hemorrhagic infarction in a patient with superior sagittal sinus thrombosis. Image 1.7Q: Catheter angiogram demonstrates absence of flow in the superior sagittal sinus (red arrow) consistent with clot within the lumen of the vein in a patient with sinus venous thrombosis. 1. Stam J. Thrombosis of the cerebral veins and sinuses. N Engl J Med. April 2005;352(17):1791–1798. 2. Ferro JM, Canhão P. Cerebral venous sinus thrombosis: updateon diagnosis and management. Curr Cardiol Rep. September 2014;16(9):523. 3. Kumral E, Polat F, Uzunköprü C, Callı C, Kitiş Ö. The clinical spectrum of intracerebral hematoma, hemorrhagic infarct, non-hemorrhagic infarct, and non-lesional venous stroke in patients with cerebral sinus-venous thrombosis. Eur J Neurol. April 2012;19(4):537–543. 4. Sagduyu A, Sirin H, Mulayim S, et al. Cerebral cortical and deep venous thrombosis without sinus thrombosis: clinical MRI correlates. Acta Neurol Scand. October 2006;114(4):254–260. 1.8 Cerebral Autosomal Dominant Arteriopathy With Subcortical Infarcts and Leukoencephalopathy An otherwise healthy, 46-year-old woman presented with migraine headaches and two lacunar strokes. Images 1.8A–1.8D: Axial FLAIR images demonstrate extensive, symmetric white matter hyperintensities with multiple old lacunar infarctions (red arrows). In particular, there is hyperintensity in the white matter of the temporal poles (pink arrow) and the external capsule (yellow arrow). Image 1.8E: Notch 3 immunohistochemical staining of small vessels shows a punctate staining of smooth muscle and pericytes with notch 3 (image credit nephron; https://commons.wikimedia.org/wiki/File:CADASIL_-_very_high_mag.jpg). 1. Chabriat H, Joutel A, Dichgans M, Tournier-Lasserve E, Bousser MG. Cadasil. Lancet Neurol. July 2009;8(7):643–653. 2. Rinnoci V, Nannucci S, Valenti R, et al. Cerebral hemorrhages in CADASIL: Report of four cases and a brief review. J Neurol Sci. July 2013;330(1–2):45–51. 3. Liem MK, Oberstein SA, van der Grond J, Ferrari MD, Haan J. CADASIL and migraine: A narrative review. Cephalalgia. November 2010;30(11):1284–1289. 1.9 Sickle Cell Disease A 13-year-old child with sickle cell disease (SCD) presented with several small strokes and cognitive impairment. Image 1.9A: Catheter angiogram demonstrates significant luminal irregularities involving the right ICA bifurcation and the M1 segment of the right MCA, with a compensatory network of hypertrophied lenticulostriate arteries in a moyamoya-like pattern. Image 1.9B: Axial FLAIR image demonstrates multiple hyperintensities in the white matter on the right. Images 1.9C and 1.9D: Anteroposterior radiograph and sagittal T1-weighted images of the spinal axes demonstrate the Lincoln Log sign and H-shaped vertebral bodies in a patient with sickle cell anemia. Image 1.9E: A peripheral smear demonstrating sickle-shaped red blood cells (image credit Drs. Noguchi, Rodgers, and Schechter of the National Institute of Diabetes and Digestive and Kidney Diseases [NIDDK]). 1. Hansen GC, Gold RH. Central depression of multiple vertebral end-plates: a “pathognomonic” sign of sickle hemoglobinopathy in Gaucher’s disease. AJR Am J Roentgenol. August 1977;129(2):343–344. 2. Lenchik L, Rogers LF, Delmas PD, Genant HK. Diagnosis of osteoporotic vertebral fractures: importance of recognition and description by radiologists. AJR Am J Roentgenol. October 2004;183(4):949–958. 3. Venkataraman A, Adams RJ. Neurologic complications of sickle cell disease. Handb Clin Neurol. 2014;120:1015–1025. 4. Gebreyohanns M, Adams RJ. Sickle cell disease: Primary stroke prevention. CNS Spectr. June 2004;9(6):445–449. 1.10 Spinal Cord Stroke A 45-year-old man awoke with back pain and paraplegia. On exam, he had no movement of or sensation in his legs. However, his joint position sense was preserved. He was incontinent of urine. Images 1.10A and 1.10B: Sagittal and axial T2-weighted images demonstrate hyperintensity of the conus medullaris (red arrows). On axial imaging, the lesion is in the gray matter. Image 1.10C: Axial-diffusion-weighted image shows restricted diffusion in the center of the spinal cord. Images 1.10D and 1.10E: Sagittal and axial T2-weighted images demonstrate hyperintensity of the anterior horn cells, the “owl’s eye” appearance on the axial image, in a patient with an anterior spinal artery infarction. 1. Rigney L, Cappelen-Smith C, Sebire D, Beran RG, Cordato D. Nontraumatic spinal cord ischaemic syndrome. J Clin Neurosci. October 2015;22(10):1544–1549. 2. Gaeta TJ, LaPolla GA, Balentine JR. Anterior spinal artery infarction. Ann Emerg Med. July 1995;26(1):90–93. 1.11 Microvascular Disease A 76-year-old man presented with subtle cognitive problems, which his wife had noticed over the past several years. Images 1.11A–1.11D: Axial FLAIR images demonstrate symmetric confluent, hyperintense periventricular lesions as well as similar lesions in the center of the pons consistent with microvascular disease (MVD). 1. Román GC, Erkinjuntti T, Wallin A, Pantoni L, Chui HC. Subcortical ischaemic vascular dementia. Lancet Neurol. November 2002;1(7):426–436. 2. Biessels GJ. Diagnosis and treatment of vascular damage in dementia. Biochim Biophys Acta. November 22, 2015.
Case History
Diagnosis: Ischemic Stroke
Introduction
The brain receives its blood supply from two paired arteries, the internal carotid arteries (ICAs) and vertebral arteries (VAs). The right common carotid artery arises from the brachiocephalic artery, while the left common carotid artery arises directly from the aortic arch. The common carotid artery divides into the external carotid artery and the ICA.
Intracranially, the ICA gives rise to the ophthalmic artery, the anterior choroidal artery, and the posterior communicating artery. It then divides into the anterior cerebral artery (ACA) and middle cerebral artery (MCA). The VAs arise from the subclavian artery and run through the transverse foramen of the cervical vertebrae. The posterior inferior cerebellar arteries (PICA) arise from the VAs, which then fuse at the pontomedullary junction to form the basilar artery. The anterior inferior cerebellar arteries (AICAs) and the superior cerebellar arteries (SCAs) arise from the basilar artery, which then divides into the paired posterior cerebral arteries (PCAs).
The anterior and posterior circulations are connected via the circle of Willis, which is composed of the ACAs, a single anterior communicating artery, the ICAs, the PCAs, and the posterior communicating arteries. A complete circle of Willis is present in less than half of the population, however.
The anterior circulation refers to those brain areas supplied by the ICAs, MCAs, and ACAs. This includes the frontal lobes, lateral temporal lobes, parietal lobes, caudate and lentiform nuclei, and internal capsule. The posterior circulation refers to those brain areas supplied by the vertebral, basilar, and PCAs. This includes the brainstem, cerebellum, occipital lobes, medial temporal lobes, and thalami.
An ischemic stroke occurs when there is a focal neurological deficit, usually of very sudden onset, lasting at least 24 hours, due to an occlusion of a blood vessel supplying the central nervous system (CNS). By definition, any deficit that lasts less than 24 hours is termed a transient ischemic attack (TIA), though most TIAs are much shorter than this. Stroke is the third leading cause of death in the United States, and is the leading cause of disability in adults. There are nearly 750,000 strokes in the United States annually causing 200,000 deaths. Eighty percent of strokes are ischemic and 20% are hemorrhagic.
Clinical Presentation
The clinical presentation depends on which vessel is occluded.
Anterior Cerebral Artery
The ACA supplies the medial portion of the frontal lobe, anterior parietal lobe, as well as the corpus callosum and cingulate gyrus. Occlusions of the ACA stem may be well tolerated as long as there is sufficient collateral flow through the anterior communicating artery.
Infarctions of the ACA produce contralateral weakness and sensory loss primarily of the leg as this part of the motor homunculus is located within the interhemispheric fissure. Urinary incontinence, to which patients are often indifferent, can be seen due to disruption of the micturition inhibition center. Patients can become disinhibited or abulic. Left-sided lesions may result in a transcortical motor aphasia, while right-sided lesions may produce hemineglect.
Middle Cerebral Artery
Infarctions of the entire MCA produce contralateral weakness, sensory loss, and a homonymous hemianopsia. Left-sided lesions result in global aphasia, while right-sided lesions cause hemineglect and lack of prosody. The eyes will be deviated to the side of the lesion due to injury to the frontal eye fields. Examples are shown in Images 1.1A–1.1C.
The MCA has three divisions: the superior division, the inferior division, and the deep branches. The superior division supplies the lateral frontal lobe above the Sylvian fissure. Infarctions of the superior division produce contralateral weakness. Infarctions on the left produce a Broca’s aphasia, while infarctions on the right produce neglect.
The inferior division supplies the posterior frontal lobe, anterior parietal lobe, and lateral temporal lobe. Infarctions on the left cause a Wernicke’s aphasia, while on the right cause left hemineglect. With either side, there will be contralateral visual field deficits due to disruption of the optic radiations, though this may be difficult to detect in patients with significant neglect or aphasia. With parietal lobe lesions, there will be cortical sensory loss. There are usually minimal to no motor findings.
The deep territory consists of the subcortical white matter and basal ganglia. Infarctions in this territory produce contralateral weakness and sensory loss. Large lesions may be associated with aphasia or neglect.
Posterior Cerebral Artery
The PCA supplies the inferior medial temporal lobe and the occipital lobe. Small penetrating branches supply parts of the midbrain and thalamus. PCA infarctions produce a contralateral homonymous hemianopsia. There may be sparing of the central vision (macular sparing) due to collateral supply to the occipital pole from the MCA. There will be sensory deficits if the thalamus is affected. Involvement of the midbrain can lead to motor deficits, upper cranial nerve palsies, vertical gaze impairment, or coma. Infarctions on the left cause alexia without agraphia if there is involvement of the splenium of the corpus callosum.
A fetal origin of the PCA occurs when the posterior communicating artery is larger than PCA. It is a common variant, occurring in 20% to 30% individuals. With pathology of the anterior circulation, there may be infarction in territories normally supplied by the posterior circulation.
Radiographic Appearance and Diagnosis
A CT scan without contrast is required for any patient who presents with the sudden onset of a neurological deficit to rule out intracranial bleeds or mass lesions that might mimic ischemic strokes. The brain parenchyma will be normal in cases of hyperacute ischemic stroke, though a clot within the lumen of the large arteries may appear hyperdense, a finding known as the “dense MCA sign.” Within the brain parenchyma itself, blurring of the distinction between the gray and white matter becomes visible after 6 to 12 hours.
After several days, the infarcted tissue becomes markedly hypodense. Swelling and edema are evident as well.
Within the core of the infarction, there is neuronal death within minutes. The ischemic penumbra refers to tissue that is at risk of infarction but can be preserved if blood flow is promptly restored. CT perfusion scans can be used acutely to determine the mean transit time (MTT), the cerebral blood flow (CBF), and the cerebral blood volume (CBV) to help determine if there is an ischemic penumbra.
Within the infarct core there will be:
Prolonged MTT or Tmax
Markedly decreased CBF
Markedly decreased CBV
Within the ischemic penumbra there will be:
Prolonged MTT or Tmax
Moderately decreased CBF
Near normal or even increased CBV
MRIs are more sensitive than CTs for acute stroke, especially smaller infarctions. Diffusion-weighted sequences, which reveal abnormal movements of water, are the most sensitive sequence for detecting acute ischemic events. If there is corresponding hypointensity (referred to as “drop-out”) on the apparent diffusion coefficient (ADC) map, then the diagnosis is confirmed in the appropriate clinical setting. Importantly, other diseases, such as active multiple sclerosis (MS) lesions, abscesses, or tumors such as primary CNS lymphoma can also demonstrate restricted diffusion. In the acute setting, the advantage of using an MRI to confirm a stroke diagnosis has to be weighed against delaying thrombolytic therapy. On magnetic resonance angiographies (MRAs), the occluded vessel can be seen.
A stroke should be the presumed diagnosis in any patient who presents with the sudden onset of focal neurological deficits. However, it is important to keep in mind potential stroke mimics. Possible stroke mimics include:
Seizures: Patients in status epilepticus or those suffering from postictal paralysis, termed Todd’s paralysis, may present with focal neurological findings. Though motor deficits are the most common postictal deficit, patients also may present with aphasias.
Migraines: Patients may present with focal neurological deficits, in which case the migraine is referred to as a complicated migraine.
Tumors: Neoplasms may present with the sudden onset of focal symptoms, especially if there is hemorrhage into the tumor.
Multiple sclerosis: Patients with MS might develop acute neurological symptoms or wake up with new symptoms. Active areas of demyelination in MS may also show diffusion restriction making the radiographic appearance similar to infarction as well.
Psychiatric disturbances: Patients with a wide variety of psychiatric disturbances may present with neurological deficits that resemble strokes. Patients may consciously feign symptoms, termed factitious disorder (or malingering if for secondary gain), or may do so unconsciously in cases of conversion disorder.
Toxic/metabolic abnormalities: Patients with toxic or metabolic abnormalities may present with focal neurological findings. This is most classically present in patients who have had a prior stroke whose symptoms reappear or worsen in the setting of systemic illness, which can be easily confused with new symptoms.
Treatment
Acute Stroke Treatment
An acute ischemic stroke is a neurological emergency. The goal of acute treatment is to preserve the ischemic penumbra. Tissue Plasminogen Activator (t-PA), a thrombolytic agent, should be given to all patients who can be treated within 3 hours, assuming there are no contraindications. Newer data indicates the time window in which treatment is effective can be extended to 4.5 hours. Without blood supply, brain tissue dies rapidly, and the earlier it is given, the greater the potential benefit. With t-PA, there is a 30% risk reduction for disability at 3 months compared to placebo. The major risk is intracranial hemorrhage, which occurs in 6% of patients. The risk for bleeding increases with larger infarctions, longer times from stroke onset, and deviation from the t-PA protocol. Aspirin is the treatment of choice for stroke patients not eligible for t-PA, and it has been shown to reduce mortality if given within the first 48 hours.
Interventional procedures can be used to mechanically remove the clot or deliver thrombolytics directly to the clot. The Mechanical Embolus Removal in Cerebral Ischemia (MERCI) trial investigated the use of a corkscrew device to mechanically remove clots within intracranial arteries within 8 hours of stroke onset. The Penumbra System is another interventional device used to aspirate and extract a clot from within the lumen of an artery.
The MR CLEAN trial demonstrated effectiveness of these interventions if done within a 6-hour window. Multiple other recent trials (SWIFT PRIME, EXTEND-IA, ESCAPE, REVASCAT) with variable inclusion criteria demonstrated unequivocal positive benefit of acute endovascular treatment of ischemic stroke in select patients with significant increase in bleeding risk. Some studies also demonstrated a trend in reduction of mortality. The likelihood of good outcome increases with higher degree of recanalization, and patients who receive earlier treatment fare better. Outcomes are best in strokes of anterior circulation.
Large infarctions of the MCA, sometimes called malignant MCA infarctions, may cause swelling, herniation, and death. The swelling peaks on days 3 to 5, and younger patients with less brain atrophy are most vulnerable. Osmotic agents such as mannitol and hyperventilation are used to lower intracranial pressure (ICP). In certain cases, removal of the skull (hemicraniectomy) may be a lifesaving procedure.
Protection against deep vein thrombosis, dysphagia screening to prevent aspiration, nursing care to prevent skin breakdown, the prevention of contractures, and the early institution of physical, occupational, and speech therapy are all crucial.
Secondary Stroke Prevention
Once patients have been stabilized, treatment involves determining the stroke mechanism, preventing a second stroke, and rehabilitation. All patients should have the following risk factors addressed:
Hypertension: Hypertension is the most important risk factor for both ischemic and hemorrhagic strokes. The risk of stroke correlates directly with blood pressure elevation, even in patients who do not meet criteria for hypertension. The goal blood pressure in stroke patients is 120/80.
Lipids: An elevated cholesterol and low-density lipoprotein (LDL) are risk factors for ischemic stroke. An elevated high-density lipoprotein (HDL) is protective. Stroke patients should be started on an HMG-CoA reductase inhibitor, even in the absence of elevated LDL.
Diabetes: Diabetes is a strong risk factor for all subtypes of stroke. Despite this, strict glycemic control has not been shown to prevent stroke.
Lifestyle: Cigarette smoking, obesity, heavy alcohol consumption, and a sedentary lifestyle should all be addressed.
Carotid stenosis: About 30% of ischemic strokes are due to artery-to-artery thromboembolism. Any vessel that precedes the intracranial vasculature may be a source of emboli, including the aortic arch, the common carotid artery, the ICAs, or the VAs. Of these, carotid bifurcation is the most common source of emboli. Patients with carotid stenosis greater than 70% benefit from intervention either by a carotid endarterectomy or stenting of the stenotic artery. This is best done as soon as patients are medically stable, as the highest risk for a second stroke is within the first 72 hours after the initial event.
Atrial Fibrillation: About 20% of ischemic strokes are cardioembolic. The most common cause is atrial fibrillation, which has a 5% risk of annual stroke. Stasis within the left atrium allows for clot formation. The clot can then dislodge to occlude an intracranial vessel.
Congestive heart failure, endocarditis, coronary artery disease, intracardiac tumors, and cardiac wall motion abnormalities, especially after a myocardial infarction, are also risk factors for cardioembolism.
Patients with a possible cardioembolic event should have a transesophageal echocardiogram to screen for an intracardiac thrombus and an electrocardiogram (EKG) to screen for atrial fibrillation. In patients with a normal EKG, prolonged cardiac monitoring should be used, as patients may have paroxysmal atrial fibrillation that is not detected on a single EKG.
In patients with an intracardiac thrombus or atrial fibrillation, anticoagulation is indicated. Using warfarin to maintain an international normalized ratio (INR) from 2 to 3 for a patient with atrial fibrillation leads to a 66% reduction in stroke, which outweighs the 1% annual bleeding rate from anticoagulation. Alternatives to warfarin are available. Dabigatran is a direct thrombin inhibitor, which has been shown to be superior to warfarin in patients with atrial fibrillation with equal rates of bleeding. Unlike warfarin, there is no way to reverse the medication in patients who experience bleeding events. Apixaban is a direct factor Xa inhibitor. In comparison with warfarin, it prevented 21% more strokes, and resulted in 31% fewer incidents of major bleeding over an average of 1.8 years. Rivaroxaban is also a direct factor Xa inhibitor. It has shown efficacy in preventing strokes in patients with atrial fibrillation. Anticoagulation is also indicated for patients with a number of different types of mechanical heart valves.
Antiplatelet agents: In patients with atherosclerotic disease, antiplatelet agents are indicated (Table 1.1.1).
About 20% of strokes are either cryptogenic or due to other mechanisms. These other mechanisms include:
Hypercoagulable states: Inherited coagulation cascade disorders usually present with strokes before the age of 30, most commonly of the venous system. Such disorders include antithrombin III deficiency, protein C and S deficiency, activated protein C resistance/factor V Leiden mutation, and prothrombin gene mutation. The antiphospholipid syndrome is a hypercoagulable state that is more common in women and may present with recurrent, spontaneous abortions. It can be screened for by testing lupus anticoagulant and anticardiolipin antibodies. Inherited coagulation cascade disorders should be treated with warfarin. Systemic malignancies can also lead to hypercoagulable states as can the use of oral contraceptive medications, particularly in women who smoke.
Paradoxical embolus: A paradoxical embolus occurs when there is atrial septal defect or patent foramen ovale allowing a venous clot to bypass the lungs and enter the left side of the heart and arterial system, eventually reaching the intracranial arteries. There is debate about the role these play in strokes, as they are not uncommon incidental findings. Surgical repair of the defect is indicated if it is felt to be the stroke mechanism.
Remote infarctions appear as encephalomalacia of affected brain areas. Compensatory enlargement of the ventricles due to destruction of the adjacent brain tissue is termed hydrocephalus ex vacuo.
With damage to the motor tracts in the cerebral cortex, there will be degeneration of the corticospinal tract throughout its course in the CNS, a finding termed Wallerian degeneration.
References
Case History
Diagnosis: Brainstem Stroke
Introduction
The brainstem consists of the midbrain, pons, and medulla. It contains cranial nerves 3 to 12 and the motor, sensory, and cerebellar pathways, and it is the site of production for many neurotransmitters. It also contains the reticular activating system, which is responsible for the maintenance of consciousness. Blood supply to the brainstem comes from the VAs and basilar artery.
Clinical Presentation
Infarctions of the brainstem produce numerous different clinical syndromes depending on the size and location of the infarction. They can be devastating events resulting in coma and death or produce only minimal symptoms and findings. Typical signs and symptoms include dizziness, vertigo, ataxia, nausea, imbalance, diplopia, nystagmus, dysarthria, and dysphagia. Brainstem pathology often produces a pattern of findings known as “crossed deficits.” This means cranial nerve findings on the same side of the lesion with motor and/or sensory findings on the opposite side of the lesion, as these pathways run contralateral in the brainstem while cranial nerves exit ipsilaterally. The reticular activating system, which is responsible for the maintenance of consciousness, is located in the brainstem, and patients can be made comatose from lesions there.
Midbrain: Infarctions of the medial midbrain result from occlusions of small penetrating arteries that arise from upper basilar artery, while infarctions of the lateral midbrain result from occlusions of the proximal PCA. The symptoms include various combinations of an ipsilateral oculomotor nerve palsy, contralateral hemiataxia and tremor (due to involvement of the red nucleus and cerebellar pathways), and contralateral weakness (due to involvement of the corticospinal tract within the cerebral peduncle).
Pons: Infarctions of the pons result from occlusions on the paramedian branches of the basilar artery. The symptoms depend on whether stroke occurs in the upper or lower pons and whether it is medial or lateral. Medial infarctions of the upper pons result in ipsilateral ataxia, internuclear ophthalmoplegia, and contralateral motor deficits. Lateral infarctions of the upper pons produce ipsilateral ataxia, dizziness, nausea, vomiting, nystagmus dysconjugate gaze, Horner’s syndrome, and contralateral sensory deficits if there is involvement of the spinothalamic tract or medial lemniscus. Medial infarctions of the lower pons result in ipsilateral ataxia, nystagmus, conjugate gaze to the side of the lesion, a sixth nerve palsy, and contralateral motor deficits. Lateral infarctions of the lower pons produce ipsilateral ataxia, dizziness, nausea, vomiting, nystagmus, dysconjugate gaze, sensory deficits of the face, facial paralysis, auditory dysfunction if there is involvement of the cochlear nucleus, and contralateral sensory deficits if there is involvement of the spinothalamic tract or medial lemniscus.
Medulla: Occlusion of the vertebral artery or the PICA results in the lateral medullary (Wallenberg) syndrome. Its features are dysphagia, hoarseness, dizziness, nausea and vomiting, nystagmus, problems with balance, gait coordination, and loss of pain and temperature sensation on the contralateral side of the body and ipsilateral side of the face. Horner’s syndrome due to disruption of the sympathetic pathways in the brainstem is often seen. Infarctions of the medial medulla are less common. These result in ipsilateral paralysis of the tongue due to damage to the hypoglossal nerve and nucleus and contralateral weakness of the arm and leg due to damage to the corticospinal tract. Involvement of the medial lemniscus results in contralateral impairment of proprioception and light touch of the contralateral body.
Basilar occlusion: An embolism that occludes the basilar artery can produce an infarction of the entire pons. This can cause what is known as “locked-in syndrome,” a condition where patients have preserved consciousness with no voluntary movements other than vertical eye movements, which are controlled by vertical gaze centers in the midbrain.
Artery of Percheron infarction: The artery of Percheron (AOP) is a variant of thalamic and midbrain vasculature characterized by a solitary arterial trunk that arises from the proximal segment of either PCA to supply the bilateral thalami and midbrain. Its occlusion may result in bilateral, symmetric paramedian thalamic infarctions. Symptoms include disorientation, confusion, hypersomnolence, deep coma, akinetic mutism, amnesia, dysarthria, aphasia, hypophonia, or dysprosody. It also supplies the rostral midbrain where infarction produces bilateral oculomotor nerve palsies.
Radiographic Appearance and Diagnosis
As with any suspected stroke, CT scans are required to rule out hemorrhage, and diffusion-weighted imaging is the most sensitive modality to detect ischemia.
Treatment
Treatment is as per ischemic stroke. As with large-vessel infarctions, thrombolysis is effective as an acute treatment in lacunar strokes. Treating hypertension, along with antiplatelet agents and other medical comorbidities, is the mainstay of treatment.
Case History
Diagnosis: Cerebellar Infarction
Introduction
Blood supply to the cerebellum comes from three major arteries.
The PICAs arise from each vertebral artery just before they fuse together to form the basilar artery. They supply the lateral medulla and most of the inferior part of the cerebellar hemispheres and vermis.
The AICAs arise from the basilar artery. They supply the inferolateral pons, the middle cerebellar peduncle, and a small part of the anterior cerebellum. They also give off the labyrinthine arteries, which supply the structures of the inner ear.
The SCAs arise from the top of the basilar artery just before it splits to form the PCAs. They supply the upper lateral pons, the superior cerebellar peduncle, and the superior part of the vermis and cerebellar hemispheres.
Clinical Presentation
PICA infarctions present with a combination of vertigo, gait ataxia, and nausea and vomiting. The lateral medullary (Wallenberg) syndrome is common as well, especially when the underlying cause is a vertebral dissection. Large PICA infarctions may cause enough swelling of the cerebellum to obstruct the fourth ventricle and cause fatal obstructive hydrocephalus. Swelling tends to peak several days after the initial stroke.
AICA infarctions present with a combination of vertigo, nausea and vomiting, nystagmus, falling to the side of the lesion due to injury to vestibular nuclei, ipsilateral hearing loss or tinnitus, and ipsilateral facial weakness and sensory loss.
SCA infarctions, though rare, present with a combination of vertigo, nausea and vomiting, headache, gait ataxia, and diplopia.
Radiographic Appearance and Diagnosis
Although CT scans are needed to rule out hemorrhages, diffusion weighted images (DWI) is the preferred imaging modality to evaluate suspected ischemic stroke. This reveals restricted diffusion in the ischemic area.
Treatment
A ventricular drain may be lifesaving in PICA infarctions and obstruction of the fourth ventricle.
References
Case History
Diagnosis: Lacunar Stroke
Introduction
Lacunar infarctions are due to occlusions in small, single arteries that penetrate to supply the deep structure of the brain. The pathological term used to describe the changes in these small arteries is lipohyalinosis, and prolonged, uncontrolled hypertension is the main risk factor.
Overall, these comprise about 20% of all ischemic strokes.
Clinical Presentation
There are several presentations:
Pure motor hemiparesis: This localizes to the posterior limb of the internal capsule, subcortical white matter, or the pons.
Pure sensory symptoms: This localizes primarily to the thalamus.
Ataxic hemiparesis: This localizes primarily to the base of the pons.
Clumsy hand/dysarthria: This localizes primarily to the base of the pons or genu of the posterior limb of the internal capsule.
They are generally not associated with the higher cortical function abnormalities, such as aphasia and neglect syndrome. Strokes in the thalamus are an exception to this, however, and can be associated with behavioral and cognitive abnormalities.
Many are clinically silent or present with cognitive decline or parkinsonism when they accumulate in large numbers.
Radiographic Appearance and Diagnosis
As with any suspected stroke, CT is the imaging modality of choice to rule out hemorrhage. Restricted diffusion on DWIs is the most sensitive MRI sequence for revealing ischemia.
Lacunar strokes occur due to occlusions of the lenticulostriate arteries of the MCA that supply the basal ganglia, internal capsule, and white matter in the corona radiata, the thalamoperforating branches of the PCA supplying the thalamus, or the penetrating branches of the basilar artery supplying the pons. The cerebellum is also vulnerable to such strokes.
Treatment
Acute treatment is as per ischemic stroke. As with large-vessel infarctions, thrombolysis is effective as an acute treatment in lacunar strokes.
As uncontrolled hypertension is the leading risk factor for lacunar strokes, managing hypertension, along with antiplatelet agents and other medical comorbidities, is the mainstay of treatment.
References
Case History
Diagnosis: Watershed Stroke
Introduction
A watershed stroke affects the brain areas farthest from direct perfusion of the major cerebral arteries. They occur in the brain areas bordered by the ACA/MCA or MCA/PCA. They account for up to 10% of strokes.
They occur when there is hypoperfusion of the brain from systemic hypotension, congestive heart failure, or a high-grade carotid stenosis. In patients without these risk factors, microemboli have been proposed as a possible mechanism.
There are two types of watershed strokes:
Clinical Presentation
Patients present with weakness of the proximal arm and leg, with preservation of strength in the hands and feet; colloquially, this is known as the “man in a barrel” presentation. Patients with left-sided strokes may develop akinetic mutism, a condition where patients can speak, but will only do so when sufficiently motivated. A neglect syndrome may be seen in right-sided strokes. For unclear reasons, seizures are more common in watershed strokes.
Radiographic Appearance and Diagnosis
As with any suspected stroke, CT scans are required to rule out hemorrhage, and diffusion-weighted imaging is the most sensitive modality to detect ischemia.
In internal watershed infarctions, there will be a ribbon of infarction in the parafalcine subcortical white matter.
In cortical watershed infarctions, the infarction appears as wedge-shaped areas of abnormality in the border zones between the MCA and ACA or the MCA and PCA.
Treatment
Treatment is per ischemic stroke, with special attention given to evaluating the ICAs for stenosis.
Reference
Case History
Diagnosis: Hypoxic-Ischemic Injury
Introduction
Hypoxic-ischemic injury occurs when there is either decreased perfusion to the brain, as in cardiac arrest, or decreased oxygenation, due to respiratory arrest, drowning, asphyxia, or carbon monoxide poisoning.
Clinical Presentation
These are typically devastating events where patients are left comatose or in a minimally conscious state. Less severely affected patients suffer from deficits in attention and memory. Patients present with a variety of movement disorders such as parkinsonism and dystonia.
Radiographic Appearance and Diagnosis
On CT, there is diffuse cortical edema with blurring of the gray–white junction. The relative hyperdensity of the cerebellum to the brain is termed the “reversal sign.” This sign is associated with a very poor prognosis.
The putamen, caudate, globus pallidus, thalami, hippocampi, and substantia nigra are particularly vulnerable to hypoxic-ischemic injury. T2-weighted images demonstrate hyperintensity of these structures, and over time they become hypodense on CT. Hippocampal abnormalities are a poor prognostic factor.
Other findings include cortical laminar necrosis and infarctions in the watershed distribution. These are best seen on DWIs and are the earliest abnormalities to be seen on neuroimaging.
Treatment
Induced hypothermia has led to improved outcomes in patients whose cardiac function can be restored in a short amount of time and is now the standard of care for patients who suffered from cardiac arrest.
References
Case History
Diagnosis: Sinus Venous Thrombosis
Introduction
The venous drainage of the brain is shown in Table 1.7.1. Cortical veins drain from the surface of the brain into the named venous sinuses. These include the superior sagittal sinus, the inferior sagittal sinus, the straight sinus, the vein of Galen, the occipital sinus, the transverse sinuses, the petrosal sinuses, and the sigmoid sinus. All of these eventually drain into the internal jugular vein. The confluence of sinuses is not an actual sinus, but rather is a reference point where the straight sinus, superior sagittal sinus, and transverse sinuses meet.
Sinus venous thrombosis (SVT) occurs when there is an occlusion of the venous system, often leading to cerebral infarction. There can be both occlusions of the deep venous system (inferior sagittal and straight sinus, and vein of Galen), as shown in the original case, and the superficial venous system (superior sagittal and transverse sinus).
Risk factors for SVT include various hypercoagulable states, pregnancy/postpartum, otitis and mastoiditis, malignancy, and medications. The combination of oral contraceptives and smoking is a particular risk factor.
Clinical Presentation
Patients present with headaches and other signs of increased ICP. In severe cases, patients may be obtunded or comatose. Seizures occur in 40% of patients. Infarction occurs in approximately 50% of cases of SVT. There is generally a more indolent presentation as compared to arterial infarcts, and infarction may occur days to weeks after clot formation. Unlike arterial infarctions, there are no specific patterns of injury with SVT, but focal neurological deficits occur depending on the part of the brain that is affected. Infarctions of the deep venous system may lead to bilateral thalamic infarcts, which produces a confusional state and a decreased level of consciousness. This may be the only manifestation of such strokes.
Radiographic Appearance and Diagnosis
Thrombosed veins may appear hyperdense on CT, a finding known as the “cord sign” when the transverse sinus is affected (Image 1.7A). An MR venogram can confirm the diagnosis in most cases.
Lack of contrast flow in the superior sagittal sinus on postcontrast images creates a triangular filling defect termed the “empty-delta sign.”
Restricted diffusion of any infarcted areas is seen within the brain parenchyma itself. The scans in Images 1.7I–1.7L demonstrate that the deep venous system may be affected as well.
In severe cases, hyperintensity is visible on T2-weighted images and frank hemorrhage may be seen.
Catheter angiography may be needed in equivocal cases. It is the most sensitive imaging modality and allows for the delivery of thrombolytics directly to the clot.
Treatment
The standard of care is immediate use of heparin even in the presence of hemorrhage. Patients are often treated with oral anticoagulation for several months, depending on the re-evaluation of the venous system. Neurointerventional procedures can be used to deliver thrombolytics directly to the clot in severe cases, and shunting of the ventricular system is required in patients with a persistently elevated ICP. Despite this, patients can become quite debilitated and die in severe cases.
References
Case History
Diagnosis: Cerebral Autosomal Dominant Arteriopathy With Subcortical Infarcts and Leukoencephalopathy
Introduction
Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the most common hereditary stroke disorder. The genetic mutation is located on the notch 3 gene on chromosome 19. It is an autosomal dominant inheritance disorder. There is degeneration of the smooth muscle cells in the microvasculature, most noticeably in the brain. Thickened blood vessels lead to impaired flow and ischemia.
The disease can present at any age, but most patients develop symptoms in mid-adulthood.
Clinical Presentation
Patients develop migraines and multiple lacunar strokes, usually in middle age and in the absence of other stroke risk factors. Visual or sensory disturbances are common during the migraines, and some patients have seizures. Psychiatric disturbances and personality changes are common. Eventually, patients become demented.
Radiographic Appearance and Diagnosis
MRI shows confluent white matter hyperintensities on T2-weighted and FLAIR images, with the vast majority having hyperintensities in the anterior temporal lobe and external capsule. Lesions in the thalamus, pons, and basal ganglia are common, and there is relative sparing of the occipital lobes and orbitofrontal cortex. Multiple old lacunar infarctions appear as cystic lesions in the basal ganglia and subcortical white matter. Microhemorrhages occur in about 50% of patients. Global cerebral atrophy is a late finding.
The arteriopathy is not limited to the CNS, and skin biopsies can be used to aid in the diagnosis.
The diagnosis is confirmed through genetic testing.
Treatment
There is no direct treatment. Antiplatelet agents are used with the hopes of preventing further infarcts. Minimization of other vascular risk factors such as smoking, hypertension, diabetes, and dyslipidemia is important. Almost all patients are demented by the age of 65 and few survive beyond 70 years of age.
References
Case History
Diagnosis: Sickle Cell Disease
Introduction
SCD is an autosomal recessive hereditary disorder, found primarily in people of African descent, though it is also seen in people with Mediterranean or Middle Eastern heritage.
In SCD, the gene that codes for the beta chain of hemoglobin (HbS) is mutated, resulting in two abnormal beta chains. The abnormal hemoglobin sticks together, creating malformed, elongated (sickle-shaped) red blood cells. They are rigid, unable to flow smoothly through the microvasculature, resulting in widespread ischemia and infarction.
Clinical Presentation
Patients most often present in early childhood with abrupt, severe pain in the bones or abdominal visceral, often in the setting of infection or dehydration. The pain is due to microvascular blockage and subsequent ischemia.
Over time, multiple organs may be involved, including the lungs (acute chest syndrome, pneumonia), renal failure, abdominal pain, autosplenectomy, bone infarction and osteomyelitis, hemolytic anemia, and severe abdominal pain.
The most common neurological complications are both large- and small-vessel strokes and cognitive dysfunction. About 25% of patients suffer from a neurological complication of the disease.
Radiographic Appearance and Diagnosis
A wide variety of findings may be seen on neuroimaging, both of the brain and spine. Cerebral atrophy is the most common finding. Both large- and small-vessel strokes are often seen. A variety of vascular malformations occur, including moyamoya syndrome, tortuous intracranial arteries, and intracranial aneurysms.
In the spine, microvascular endplate infarction causes central endplate depression, with sparing of the anterior and posterior margins. This creates a “Lincoln Log” or “H-shaped” appearance to the vertebral bodies. This finding is not specific to SCD, however, and may also be seen in Gaucher’s disease.
A peripheral smear will reveal the characteristic sickle-shaped red blood cells.
Treatment
Vaso-occlusive crises are treated with pain medications, oxygen, and hydration and analgesia. Hydroxyurea is used to minimize the severity of vaso-occlusive crises. Blood transfusions can be used to treat patients with symptomatic anemia. Screening children over the age of 2 with transcranial Doppler ultrasound and transfusing blood when there is a high stroke risk (>200 cm/sec) can reduce the risk of stroke by over 90%. Antiplatelet and antithrombotic agents have not been formally tested in stroke prevention. Bone marrow transplants are the only known cure.
References
Case History
Diagnosis: Anterior Spinal Artery Infarction
Introduction
The spinal cord receives its blood supply from a single anterior spinal artery (ASA) on the ventral surface of the cord and two paired posterior spinal arteries (PSAs) on the dorsal surface, though these often are not found below the mid-thoracic level. The ASA supplies the anterior two-thirds of the cervical and upper thoracic spinal cord, while the PSAs supply the dorsal columns.
Rostrally, the spinal arteries arise from the vertebral arteries and from feeders known as segmental arteries. In the thoracic and lumbar area, the feeders to the spinal cord are known as radicular arteries that arise from the posterior aspect of aorta. One of the largest radicular arteries is the artery of Adamkiewicz, which arises from a left posterior intercostal artery and supplies the lower two-thirds of the spinal cord.
The middle thoracic cord is a watershed area that is vulnerable to ischemic insults in the setting of systemic hypotension, abdominal surgeries, or pathology of the descending aorta, particularly near the artery of Adamkiewicz.
Punitive causes of ASA infarction are vasculitis, particularly systemic lupus erythematosus associated with antiphospholipid antibodies, advanced atherosclerosis, dissecting aneurysm (occludes or shears segmental spinal arteries at their origins), cholesterol embolism (after surgical procedures, angioplasty, or cardiopulmonary resuscitation [CPR]), fibrocartilaginous embolism, rupture of spinal arteriovenous malformation (AVM), cardioembolic disease, systemic hypotension, or surgical manipulation of the aorta. Often times, no cause is found.
Clinical Presentation
ASA infarction involves the anterior two-thirds of the spinal cord, with a variable vertical extent. It is characterized by quadriplegia or paraplegia and loss of pain and temperature below the lesion. Additional features include autonomic dysfunction and bowel and bladder retention or incontinence. Respiration can be compromised if the upper cervical cord is affected. Significant pain is common. Patients may present acutely with lower motor neuron signs, namely flaccidity and areflexia, due to spinal shock. Light touch and joint position sense are retained due to sparing of the dorsal columns.
Unlike cerebral infarctions in which symptom onset is nearly instantaneous, ASA infarctions may progress over 10 to 12 hours.
Radiographic Appearance and Diagnosis
On MRI, T2-weighted images show hyperintensities in the anterior two-thirds of the spinal cord. The gray matter is often affected preferentially. Restricted diffusion can be detected within hours and persists up to 1 week. There is minimal to no enhancement on postcontrast images. In hyperacute cases, an “owl eye” appearance can be seen, due to hyperintensity of the anterior horn cells, though this finding may be seen in other neurological disorders such as neuromyelitis optica.
In certain cases, a spinal angiogram may be needed to document the occlusion and differentiate infarction from inflammatory or infectious myelopathies. However, in contrast to these myelopathies, cerebrospinal fluid (CSF) is normal in ASA infarction.
Treatment
There is no direct treatment, and supportive treatment involves care of bladder and bowel function along with active rehabilitation. Only half of patients regain the ability to walk independently.
References
Case History
Diagnosis: Microvascular Disease
Introduction
Vascular dementia (VD), also known as multi-infarct dementia, is classically characterized by a gradual, step-wise decline in cognition. This pattern may be subtle or absent, however, as the infarctions may be clinically silent or the patient may recover function prior to his or her presentation. The term subcortical vascular dementia (Binswanger’s disease) refers specifically to subcortical vascular dementia.
Differences in screening methods and diagnostic criteria lead to some variability in reports of prevalence and incidence. Estimations, however, suggest a prevalence of 1.2% to 4.2% of individuals over the age of 65.
MVD is a frequent cause of hyperintensities on FLAIR and T2-weighted images. It is most commonly seen in elderly patients with hypertension and other vascular risk factors such as smoking, diabetes, and dyslipidemia.
Clinical Presentation and Diagnosis
In older patients, some degree of MVD is a normal finding. Extensive disease may cause a subcortical dementia. Its characteristic features include:
Focal motor signs
Early gait disturbance, such as magnetic gait or parkinsonian gait
History of unsteadiness or frequent falls
Early unexplained urinary frequency, urgency, or incontinence
Pseudobulbar palsy
Personality changes, such as apathy and depression
Cognitive impairment, particularly in executive function
Diagnosis and Radiographic Appearance
MVD appears as white matter hyperintensities on FLAIR and T2-weighted images. There is no mass effect or contrast enhancement. In many cases, the lesions of MVD may be difficult to distinguish from those of MS. White matter (WM) lesions due to MVD are much more common than in MS, especially in elderly patients, making the history and physical of paramount importance in evaluating patients. The lesions in MVD are scattered more throughout the white matter of the brain as opposed to the periventricular location most commonly seen in MS. Additionally, lesions are usually not seen in the corpus callosum or below the tentorium as in MS, though lesions are possible in these locations. In severe cases of MVD, the white matter lesions take on a confluent appearance.
Treatment
Individuals with mild cognitive impairment or evidence of mild cerebrovascular disease on imaging should be counseled on risk factor reduction. These include control of hypertension, diabetes management, and lifestyle and behavioral changes, such as healthy diet, smoking cessation, and exercise.
References
Related posts:
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
