MISCELLANEOUS 15.1 Behcet’s Disease A 42-year-old man from Jordan presented with severe dysarthria, imbalance, and diplopia. Images 15.1A–15.1C: Axial and sagittal fluid-attenuated inversion recovery (FLAIR) images demonstrate hyperintensity of the pontine tegmentum, midbrain, and pons. Images 15.1D and 15.1E: Postcontrast axial T1-weighted images demonstrate patchy enhancement of the lesions in the pons. 1. Anal or genital ulcers (including orchitis or epididymitis in males). 2. Dermatological lesion such as erythema nodosum, acne, or folliculitis. 3. Ocular inflammation including uveitis, iritis, or retinal vasculitis. 4. Positive pathergy reaction, defined as a papule larger than 2 mm, 24 to 48 hours after a needle prick. Image 15.1F: MR venogram demonstrates clot in the right transverse sinus (red arrow) and superior sagittal sinus (yellow arrow). Image 15.1G: Axial CT image demonstrates hyperdensity in the right transverse sinus corresponding to the clot (blue arrow). Image 15.1H: An oral ulcer in a patient with Behcet’s disease (pink arrow) (image credit Drs. Ahmet Altiner and Rajni Mandal). 1. Peño IC, De las Heras Revilla V, Carbonell BP, et al. Neurobehçet: clinical and demographic characteristics. Eur J Neurol. September 2012;19(9):1224–1227. 2. Houman MH, Bellakhal S, Ben Salem T, et al. Characteristics of neurological manifestations of Behçet’s: a retrospective monocentric study in Tunisia. Clin Neurol Neurosurg. October 2013;115(10):2015–2018. 3. Aguiar de Sousa D, Mestre T, Ferro JM. Cerebral venous thrombosis in Behçet’s disease: a systematic review. J Neurol. May 2011;258(5):719–727. 15.2 Neurosarcoidosis A 45-year-old man developed seizures and cognitive impairment. Images 15.2A–15.2D: Axial FLAIR and postcontrast T1-weighted images demonstrate an enhancing, spiculated lesion in the left temporal and parietal lobes with surrounding edema. There are different patterns of parenchymal involvement in neurosarcoidosis. Images 15.2E–15.2G: Axial and sagittal FLAIR and postcontrast axial T1-weighted images demonstrate multiple white matter lesions with a cortical lesion in the right frontal lobe. Many of the lesions enhance. Images 15.2H–15.2J: Axial FLAIR and postcontrast T1-weighted images from another patient demonstrate extensive white matter and cortical hyperintensities with linear streaks of enhancement predominantly in the left frontal lobe. Leptomeningeal enhancement is common, particularly around the basal cisterns. The enhancement may be smooth or nodular. It can cause a vasculitis with resultant infarction, and over time there may be significant hydrocephalus. Pituitary/hypothalamic and cranial nerve involvement is seen in 40% of the cases. The facial and optic nerves are most commonly involved, though any cranial nerve can be affected. Involvement of the cranial nerves, pituitary gland, and hypothalamus often occurs with extensive involvement of the basilar meninges, but may occur in isolation. Examples from two different patients are shown in Images 15.2O–15.2T. The myelopathy of sarcoidosis leads to a swollen spinal cord, with intramedullary enhancement and often of the meninges surrounding the cord. It preferentially affects the cervical spine. This form of neurosarcoidosis has the worst prognosis. Images 15.2K–15.2N: Postcontrast axial and coronal T1-weighted images demonstrate extensive leptomeningeal enhancement, primarily in the basal cisterns. Images 15.2O–15.2Q: Postcontrast axial T1-weighted images demonstrate enhancement of the facial (red arrow), trigeminal (orange arrow), and oculomotor (blue arrow) nerves bilaterally in a patient with sarcoidosis. Images 15.2R–15.2T: Postcontrast sagittal, coronal, and axial T1-weighted images demonstrate enhancement of the hypothalamus (red arrows) and oculomotor nerve (blue arrows). Images 15.2U–15.2W: Sagittal T2-weighted and postcontrast sagittal and axial T1-weighted images demonstrate a longitudinally extensive myelitis with cord swelling and enhancement (red arrows) of the dorsal columns in a patient with neurosarcoidosis. 1. Tavee JO, Stern BJ. Neurosarcoidosis. Continuum (Minneap Minn). June 2014;20(3 Neurology of Systemic Disease):545–559. 2. Schwendimann RN, Harris MK, Elliott DG, et al. Neurosarcoidosis: clinical features, diagnosis, and management. Am J Ther. May–June 2013;20(3):292–299. 3. Vargas DL, Stern BJ. Neurosarcoidosis: diagnosis and management. Semin Respir Crit Care Med. August 2010;31(4):419–427. 4. Stjepanović MI, Vucinić VM, Jovanović D, Mijajlović M, Trifunović VS, Stjepanović MM. Treatment of neurosarcoidosis: innovations and challenges. Med Pregl. May–June 2014;67:161–166. 15.3 Langerhans Cell Histiocytosis A 17-year-old girl presented with bone pain, hearing loss, and excessive urination. Images 15.3A–15.3C: Postcontrast sagittal and axial T1-weighted images demonstrate enhancement of the infundibulum and hypothalamus (red arrow), an enhancing mass in the temporal bone (blue arrow), and enhancement of the dentate nuclei (yellow arrow). Image 15.3D: Axial FLAIR image demonstrates symmetrical hyperintensity in the dentate nuclei and medial lemniscus in the pons. 1. Gabbay LB, Leite Cda C, Andriola RS, Pinho Pda C, Lucato LT. Histiocytosis: a review focusing on neuroimaging findings. Arq Neuropsiquiatr. July 2014 Jul;72(7):548–558. 2. Prayer D, Grois N, Prosch H, Gadner H, Barkovich AJ. MR imaging presentation of intracranial disease associated with Langerhans cell histiocytosis. AJNR Am J Neuroradiol. May 2004;25(5):880–891. 3. Gabbay LB, Leite Cda C, Andriola RS, Pinho Pda C, Lucato LT. Histiocytosis: a review focusing on neuroimaging findings. Arq Neuropsiquiatr. July 2014;72(7):548–558. 4. Prayer D, Grois N, Prosch H, Gadner H, Barkovich AJ. MR imaging presentation of intracranial disease associated with Langerhans cell histiocytosis. AJNR Am J Neuroradiol. May 2004;25(5):880–891. 15.4 Tolosa–Hunt Syndrome A 35-year-old man developed severe facial pain and double vision. Images 15.4A and 15.4B: Postcontrast, fat-suppressed axial and coronal T1-weighted images demonstrate an enhancing lesion (red arrows) in the left cavernous sinus. 1. One or more episodes of unilateral orbital pain persisting for weeks if untreated. 2. Paresis of one or more of the third, fourth, and/or sixth cranial nerves and/or demonstration of granuloma by MRI or biopsy. 3. Paresis coincides with the onset of pain or follows it within 2 weeks. 4. Pain and paresis resolve within 72 hours when treated adequately with corticosteroids. 5. Other causes have been excluded by appropriate investigations. 1. Jain R, Sawhney S, Koul RL, Chand P. Tolosa-Hunt syndrome: MRI appearances. J Med Imaging Radiat Oncol. October 2008;52(5):447–451. 2. Kline LB, Hoyt WF. The Tolosa-Hunt syndrome. J Neurol Neurosurg Psychiatry. November 2001;71(5):577–582. 3. Sánchez Vallejo R, Lopez-Rueda A, Olarte AM, San Roman L. MRI findings in Tolosa-Hunt syndrome (THS). BMJ Case Rep. November 2014;2014. 15.5 Orbital Pseudotumor A 23-year-old woman presented with double vision, proptosis, and pain of her right eye. Images 15.5A and 15.5B: Axial FLAIR and coronal T1-weighted images demonstrate hyperintensity and enlargement of the right lateral rectus muscle (red arrows). 1. Myositic 2. Lacrimal 3. Anterior—involvement of the globe, retrobulbar orbit 4. Diffuse—multifocal intraconal involvement with or without an extraconal component 5. Apical—involving the orbital apex and with intracranial involvement 1. Montagnese F, Wenninger S, Schoser B. “Orbiting around” the orbital myositis: clinical features, differential diagnosis and therapy. J Neurol. 2016;263(4):631–640. 2. Costa RM, Dumitrascu OM, Gordon LK. Orbital myositis: diagnosis and management. Curr Allergy Asthma Rep. July 2009;9(4):316–323. 15.6 Orbital Cavernous Venous Malformation A 40-year-old woman presented with double vision and proptosis. Images 15.6A–15.6D: Axial T2-weighted, noncontrast T1-weighted, and postcontrast coronal and axial T1-weighted images demonstrate an avidly enhancing ovoid intraconal mass in the right inferolateral orbit, which is separate from the optic nerve and displaces it superomedially. 1. Rootman DB, Heran MK, Rootman J, White VA, Luemsamran P, Yucel YH. Cavernous venous malformations of the orbit (so-called cavernous haemangioma): a comprehensive evaluation of their clinical, imaging and histologic nature. Br J Ophthalmol. July 2014;98(7):880–888. 2. Khan SN, Sepahdari AR. Orbital masses: CT and MRI of common vascular lesions, benign tumors, and malignancies. Saudi J Ophthalmol. October 2012;26(4):373–383. 15.7 Dilated Perivascular Spaces A 90-year-old man presented with mild cognitive impairment. Images 15.7A–15.7D: Axial T2-weighted and FLAIR images demonstrate the “colander-like” appearance of multiple dilated perivascular spaces and mild white matter disease. 1. Type 1: found in the basal ganglia along the course of the lenticulostriate arteries 2. Type 2: found in the cortex along the course of the medullary arteries 3. Type 3: found in the midbrain 1. Akiguchi I, Shirakashi Y, Budka H, et al. Disproportionate subarachnoid space hydrocephalus—outcome and perivascular space. Ann Clin Transl Neurol. August 2014;1(8):562–569. 2. Román GC. On the history of lacunes, etat criblé, and the white matter lesions of vascular dementia. Cerebrovasc Dis. 2002;13(Suppl. 2):1–6. 15.8 Fibrous Dysplasia of the Skull A 20-year-old woman presented with slowly progressive decreased visual acuity. Images 15.8A and 15.8B: Axial CT images demonstrate an infiltrative, expansile process of the skull base with “ground glass” matrix mineralization consistent with fibrous dysplasia. Images 15.8C and 15.8D: Café-au-lait skin macules with a “jagged coast of Maine” appearance in McCune–Albright syndrome. Source: Dumitrescu CE, Collins MT. McCune-Albright syndrome. Orphanet J Rare Dis. 2008;3:12. 1. Bowers CA, Taussky P, Couldwell WT. Surgical treatment of craniofacial fibrous dysplasia in adults. Neurosurg Rev. January 2014;37(1):47–53. 2. Salenave S, Boyce AM, Collins MT, Chanson P. Acromegaly and McCune-Albright syndrome. J Clin Endocrinol Metab. June 2014;99(6):1955–1969. 3. Frisch CD, Carlson ML, Kahue CN, et al. Fibrous dysplasia of the temporal bone: a review of 66 cases. Laryngoscope. June 2015;125(6):1438–1443. 4. Dumitrescu CE, Collins MT. McCune-Albright syndrome. Orphanet J Rare Dis. 2008;3:12. 15.9 Hyperostosis Frontalis A 46-year-old woman presented with a seizure. She was obese and had been diagnosed with depression and diabetes several years earlier. Images 15.9A–15.9D: Sagittal T1-weighted and axial T2-weighted images and axial CT images in bone and brain windows demonstrate bony overgrowth (red arrows) in the frontal lobes consistent with hyperostosis frontalis interna. 1. Raikos A, Paraskevas GK, Yusuf F, et al. Etiopathogenesis of hyperostosis frontalis interna: a mystery still. Ann Anat. October 2011;193(5):453–458. 2. She R, Szakacs J. Hyperostosis frontalis interna: case report and review of literature. Ann Clin Lab Sci. Spring 2004;34(2):206–208. 15.10 Idiopathic Intracranial Hypertension An obese 30-year-old female presented with severe headaches and visual loss. On exam, she had an enlarged blind spot and papilledema. Images 15.10A–15.10C: Sagittal T1-weighted and axial T2-weighted images demonstrate an empty sella (red arrows), papilledema with flattening of the posterior globe (yellow arrows), distension of the optic nerve sheath in the subarachnoid spaces (blue arrow), and tortuous optic nerves consistent with the diagnosis of idiopathic intracranial hypertension. Image 15.10D: Axial FLAIR image demonstrates “slit-like ventricles” and effacement of the basal cisterns in another patient with idiopathic intracranial hypertension. 1. Symptoms of raised ICP (headache, nausea, vomiting, transient visual obscurations, or papilledema) 2. No localizing signs with the exception of abducens nerve palsy 3. The patient is awake and alert. 4. No imaging evidence of thrombosis 5. Cerebrospinal fluid opening pressure greater than 25 cmH2O and otherwise normal CSF 6. No other explanation for the raised intracranial pressure Image 15.10E: Severe papilledema. Source: Garcia T, Bonnay G, Tourbah A, Arndt C. Optical coherence tomography in neuro-ophthalmology. In: Kawasaki M, ed. Optical Coherence Tomography. 1. Kosmorsky GS. Idiopathic intracranial hypertension: pseudotumor cerebri. Headache. February 2014;54(2):389–393. 2. Wall M. Idiopathic intracranial hypertension. Neurol Clin. August 2010;28(3):593–617. 3. Thurtell MJ, Wall M. Idiopathic intracranial hypertension (pseudotumor cerebri): recognition, treatment, and ongoing management. Curr Treat Options Neurol. February 2013;15(1):1–12. 15.11 Intracranial Hypotension A 45-year-old female developed a severe headache after a lumbar puncture. Image 15.11A: Sagittal T1-weighted image demonstrates “brain sagging” including descent of the cerebellar tonsils with crowding the foramen magnum (red arrow), flattening of the ventral pons against the clivus (blue arrow), inferior displacement of the third ventricle and drooping of the splenium of the corpus callosum (yellow arrows), and near complete effacement of the basal cisterns. Images 5.11B and 15.11C: Postcontrast sagittal T1-weighted images demonstrate prominent engorgement of the dural venous sinuses (green arrows). The transverse sinus is rounded, with a convex inferior margin (pink arrow), the venous distension sign. Image 15.11D: Postcontrast coronal T1-weighted image demonstrates diffuse meningeal enhancement. Images 15.11E and 15.11F: Axial CT images demonstrate chronic bilateral subdural collections with mass effect in a patient with prolonged intracranial hypotension. 1. Urbach H. Intracranial hypotension: clinical presentation, imaging findings, and imaging-guided therapy. Curr Opin Neurol. August 2014;27(4):414–424. 2. Spears RC. Low-pressure/spinal fluid leak headache. Curr Pain Headache Rep. June 2014;18(6):425. 3. Mokri B. Spontaneous intracranial hypotension. Curr Neurol Neurosci Rep. March 2001;1(2):109–117. 4. Schievink WI, Maya MM, Moser FG, Tourje J. Spectrum of subdural fluid collections in spontaneous intracranial hypotension. J Neurosurg. October 2005;103(4):608–613. 15.12 Copper-Beaten Skull A 12-year-old child presented with severe headaches and visual loss. She had papilledema on fundoscopic exam and a lumbar puncture revealed an increased opening pressure. Images 15.12A and 15.12B: Skull radiographs reveal a “copper-beaten” skull. 1. Tuite GF, Evanson J, Chong WK, et al. The beaten copper cranium: a correlation between intracranial pressure, cranial radiographs, and computed tomographic scans in children with craniosynostosis. Neurosurgery. October 1996;39(4):691–699. 2. Agrawal D, Steinbok P, Cochrane DD. Significance of beaten copper appearance on skull radiographs in children with isolated sagittal synostosis. Childs Nerv Syst. December 2007;23(12):1467–1470. 15.13 Tension Pneumocephalus A 65-year-old man developed a severe headache and decreased level of consciousness after a neurosurgical procedure. Images 15.13A and 15.13B: Axial CT images demonstrate pneumocephalus with severe compression of the frontal lobes bilaterally: the “Mount Fuji” sign. Image 15.13C: Axial CT image demonstrates hypodensity in the frontal horns of the lateral ventricles and in the subdural space over the left frontal lobe consistent with air. 1. Pulickal GG, Sitoh YY, Ng WH. Tension pneumocephalus. Singapore Med J. March 2014;55(3):e46–e48. 2. Naraghi M, Ghazizadeh M. Tension pneumocephalus: a life-threatening complication of septoplasty and septorhinoplasty. B-ENT. 2012;8(3):203–205. 3. Haran RP, Chandy MJ. Symptomatic pneumocephalus after transsphenoidal surgery. Surg Neurol. December 1997;48(6):575–578. 15.14 Cervical Spondylotic Myelopathy A 66-year-old man presented with several falls over the course of the past few months. He said that his legs felt weak and his walking speed and endurance had declined significantly over the past few years. On examination, he had symmetrical weakness of his legs and mild weakness of his hand. He had a “scissoring” gait. His reflexes were extremely brisk in his legs with upgoing toes bilaterally. Images 15.14A–15.14C: Sagittal T2-weighted and postcontrast T1-weighted and axial T1-weighted images demonstrate severe cervical spondylosis with intrinsic spinal cord hyperintensity on T2-weighted images and enhancement (red arrow) on postcontrast imaging. On the axial image, the spinal cord (yellow arrow) is flattened with effacement of the surrounding cerebrospinal fluid. 15.15 Spinal Disc Herniation A 46-year-old woman developed pain in her left arm and weakness of elbow extension. Images 15.15A and 15.15B: Axial and sagittal T2-weighted images of the cervical spine demonstrate a herniated disc at C5–C6, eccentric to the right, with mass effect of the thecal sac and spinal cord compression. Note that there is hyperintensity in the cord indicating edema or myelomalacia. 1. Median: Thickness of the posterior longitudinal ligament prevents most herniations in this area. 2. Paramedian: This is the most common area for disc herniations as the posterior longitudinal ligament is thin. Illustration 15.15.1: Normal vertebral anatomy and a herniated disc (image credit debivort; https://commons.wikimedia.org/wiki/File:ACDF_coronal_english.png). Illustration 15.15.2: Focal and broad-based disc herniations. Illustration 15.15.3: Localization of herniated discs on the axial plane. 3. Intervertebral foramen: These account for less than 10% of disc herniations, but are highly symptomatic. 4. Extraforaminal: Disc herniations in this area are not common. Images 15.15C–15.15E: Sagittal T1-weighted and sagittal and axial T2-weighted images of the lumbar spine demonstrate a large herniated disc (red arrows) with superior and inferior extension. There is mass effect on the thecal sac and lower cauda equina. 1. Schmid SL, Wechsler C, Farshad M, et al. Surgery for lumbar disc herniation: analysis of 500 consecutive patients treated in an interdisciplinary spine centre. J Clin Neurosci. January 2016;27:40–43. 2. Wong JJ, Côté P, Quesnele JJ, Stern PJ, Mior SA. The course and prognostic factors of symptomatic cervical disc herniation with radiculopathy: a systematic review of the literature. Spine J. August 2014;14(8):1781–1789. 3. Bhagawati D, Gwilym S. Neck pain with radiculopathy. BMJ Clin Evid. December 23, 2015;2015. pii: 1103. 15.16 Ankylosing Spondylitis A 23-year-old man presented with back stiffness and pain, particularly in the morning. Images 15.16A and 15.16B: Sagittal CT images of the cervical and thoracic spine reveal straightening of the spine, the so-called “bamboo spine” appearance of ankylosing spondylitis. 1. Elalouf O, Elkayam O. Long-term safety and efficacy of infliximab for the treatment of ankylosing spondylitis. Ther Clin Risk Manag. November 2015;11:1719–1726. 2. Braun J, Sieper J. Ankylosing spondylitis. Lancet. April 2007;369(9570):1379–1390. 15.17 Brain Herniation Syndromes A 16-year-old boy presented with headaches and became unconscious. Images 15.17A and 15.17B: Noncontrast axial and postcontrast sagittal T1-weighted images demonstrate tonsillar herniation (red arrow) and flattening of the pons against the clivus in a patient with a large, cystic cerebellar mass. There is also upward herniation of the cerebellum. Image 15.17C: Gross image demonstrating tonsillar herniation (red arrow). Illustration 15.17.1: Illustration of the herniation syndromes (image credit Rupert Millard). Images 15.17D and 15.17E: Postcontrast axial and coronal T1-weighted images demonstrate uncal herniation in a patient with a right temporal lobe glioma. Image 15.17F: CT image demonstrates uncal herniation in a patient with a right temporal lobe hemorrhage. Image 15.17G: Gross pathology demonstrating (red arrow) compression of the midbrain (image 15.17G credit Dimitri Agamanolis, MD). Images 15.17H and 15.17I: Axial T2-weighted image demonstrates uncal herniation compressing the left posterior cerebral artery (yellow arrow). A follow-up CT image 2 weeks later shows infarction in the left PCA territory (red arrow). Images 15.17J and 15.17K: Gross specimens demonstrate Duret hemorrhages of the midbrain and pons. Images 15.17L and 15.17M: Postcontrast axial and coronal T1-weighted images demonstrate subfalcine (cingulate) herniation (red arrows) in a patient with a right frontal lobe glioma. Image 15.17N: Gross pathology demonstrates subfalcine (cingulate) herniation (red arrow) due to hemorrhagic tumor (image credit www.wikidoc.org via Professor Peter Anderson, DVM, PhD, and published with permission © PEIR, University of Alabama at Birmingham, Department of Pathology). Image 15.17O: Axial CT scan demonstrates herniation of the cerebellum outside of a surgical defect. Image 15.17P: Axial CT scan demonstrates brain herniation after a left hemicraniectomy in a patient with a large MCA infarct. Image 15.17Q: Sagittal T2-weighted image demonstrates upward herniation of the midbrain (red arrow) and cerebellum (blue arrow) in a patient with a cerebellar mass. 1. Crudele A, Shah SO, Bar B. Decompressive Hemicraniectomy in Acute Neurological Diseases. J Intensive Care Med. August 2015. 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. 15.18 Brain Death An 85-year-old female was found unconscious at home and was nonresponsive on exam without brainstem reflexes. Images 15.18A and 15.18B: Catheter angiogram reveals no cerebral flow with injection of either internal carotid artery (red arrows) in a patient after a severe hypoxic event. Flow is seen in the external carotid artery and its branches. This is evidence of brain death. The American Academy of Neurology Guidelines for brain death determination are summarized as follows: 1. The patient is comatose: 2. Brainstem reflexes are absent: 3. Apnea: 1. Scott JB, Gentile MA, Bennett SN, Couture M, MacIntyre NR. Apnea testing during brain death assessment: a review of clinical practice and published literature. Respir Care. March 2013;58(3):532–538. 2. Wijdicks EF, Varelas PN, Gronseth GS, Greer DM. American Academy of Neurology. Evidence-based guideline update: determining brain death in adults: report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology. June 2010;74(23):1911–1918. 3. Teitelbaum J, Shemi SD. Neurologic determination of death. Neurol Clin. November 2011;29(4):787–799. 4. Webb A, Samuels O. Brain death dilemmas and the use of ancillary testing. Continuum (Minneap Minn). June 2012;18(3):659–668.
Case History
Diagnosis: Behcet’s Disease
Introduction
Behcet’s disease is a systemic, necrotizing vasculitis, most commonly seen in the Middle East and Central Asia.
Clinical Presentation
Patients develop oral and genital ulcers and can have ocular manifestations (uveitis or retinal vasculitis). Multiple organ systems, including the gastrointestinal, pulmonary, musculoskeletal, cardiovascular, and neurological systems can be involved.
The formal diagnostic criteria for Behcet’s disease are oral ulcers at least thrice (in any 12-month period), along with two out of the following four symptoms:
The central nervous system (CNS) is involved in 30% to 40% of patients, and only rarely are CNS manifestations the presenting symptom. The symptoms are not specific and include headache, lethargy, cranial neuropathies, ataxia, weakness, and sensory disturbances. Meningitis and sinus venous thrombosis are other possible presentations.
Radiographic Appearance and Diagnosis
The most commonly involved areas are the basal ganglia, brainstem, and subcortical white matter. Lesions are hyperintense on T2-weighted images with mass effect and edema. There is a variable pattern of enhancement with the administration of contrast. As in this case, the pontomedullary junction is a common location for brainstem lesions. In patients without systemic manifestations of Behcet’s disease, these lesions may be indistinguishable from neoplasms. Lesions may also be seen in the basal ganglia, thalami, optic nerves, and, rarely, the spinal cord.
Sinus venous thrombosis will appear as clots in the venous system.
It is associated with HLA-B51, and this is frequently tested.
General examination may reveal oral or genital ulcers.
Treatment
It is treated with immunosuppression or with tumor necrosis factor (TNF)-alpha inhibitors, such as etanercept or infliximab.
References
Case History
Diagnosis: Neurosarcoidosis
Introduction
Sarcoidosis is an idiopathic disease characterized by noncaseating granulomas, primarily in the lung. Approximately 10% of patients have involvement of the CNS, though isolated CNS involvement is unusual. It affects women more commonly than men, usually between the ages of 30 and 40.
Clinical Presentation
Neurosarcoidosis can present with a wide spectrum of clinical manifestations, which can prove a diagnostic challenge in patients without systemic manifestations. The most common form of CNS involvement is a basilar meningitis that presents with hydrocephalus and cranial neuropathies. The optic and facial nerves are the most commonly affected, and involvement of the facial nerve may be bilateral. Any of the cranial nerves may be affected, however, leading to diplopia, dysphagia, hearing loss, vertigo, and tongue weakness. Leptomeningeal involvement occurs in nearly 50% of patients and may lead to hydrocephalus.
Involvement of the pituitary gland may lead to diabetes insipidus and other endocrinopathies, while hypothalamic involvement can lead to changes in appetite and temperature dysregulation.
Parenchymal involvement can cause seizures, cognitive impairment, psychiatric disturbances, and focal neurological deficits.
Involvement of the spinal cord and spinal nerve roots may cause a severe, painful myelopathy.
The peripheral and autonomic nervous systems can be involved as well.
Radiographic Appearance and Diagnosis
The imaging findings are highly variable, reflecting the diverse clinical picture in neurosarcoidosis. The imaging findings are nonspecific and may mimic neoplastic or demyelinating disease. CNS disease takes several forms: parenchymal involvement, leptomeningeal involvement, and involvement of the pituitary gland/stalk, hypothalamus, and cranial nerves. The spinal cord may also be involved.
Parenchymal Involvement
Enhancing mass: As seen in Images 15.2A–15.2D, neurosarcoidosis may present as an enhancing mass that is hyperintense on T2-weighted images with nodular or solid enhancement.
White matter disease: White matter disease with perivascular enhancement may be difficult to distinguish from multiple sclerosis. Examples from two different patients are shown in Images 15.2E–15.2J.
Leptomeningeal Involvement
Pituitary Gland and Stalk, Hypothalamus, Cranial Nerves
Spinal Cord
Cerebrospinal fluid (CSF) analysis commonly reveals a moderate lymphocytic pleocytosis and elevated protein. A low CSF glucose (hypoglycorrhachia) is highly suggestive of this diagnosis. Oligoclonal bands will be present in about 30% of cases. Serum angiotensin converting enzyme (ACE) is elevated in half of the patients.
In cases without systemic manifestations, the diagnosis may be difficult, and a chest CT or PET scan should be performed in suspected cases to screen for occult disease in the lungs or lymph nodes. A biopsy is often required to confirm the diagnosis.
Treatment
It is treated with a combination of steroids and immunosuppression. Infliximab has been used in treatment-refractory cases.
References
Case History
Diagnosis: Langerhans Cell Histiocytosis
Introduction
Langerhans cell histiocytosis is a multiorgan disease that usually occurs in young children. Excess immature Langerhans cells form granulomas.
It is a rare disease affecting only about 1 to 2 in 100,000 people.
Clinical Presentation
It most commonly affects the bones, leading to pain, swelling, and fractures. Patients with involvement of the CNS present with a degenerative course of highly variable severity and speed. CNS disease usually manifests as diabetes insipidus due to involvement of the hypothalamic–pituitary axis. Cranial-facial involvement due to bone destruction of the skull and orbits is also common.
Radiographic Appearance
The most common findings are bony lesions of the skull or craniofacial bones. Dural-based masses, cystic lesions of the pineal gland, infundibular thickening, choroid-plexus lesions, prominent, dilated Virchow–Robin spaces, T2 hyperintensity of the pons and dentate nucleus of the cerebellum, and brain atrophy are all well described.
Histology is needed to confirm the diagnosis.
Treatment
Systemic disease requires treatment with steroids and chemotherapy. Even with treatment, mortality may approach 10%.
References
Case History
Diagnosis: Tolosa–Hunt Syndrome
Introduction
Tolosa–Hunt syndrome is an idiopathic granulomatous disease of the cavernous sinus and orbital apex.
Clinical Presentation
It presents as a painful, unilateral ophthalmoplegia. Involvement of the optic nerve occurs in 25% of patients, and sensory loss in the distribution of the first two divisions of the trigeminal nerve is common. The symptoms typically present over the course of days to weeks.
The International Headache Society criteria for Tolosa–Hunt syndrome are:
Radiographic Appearance and Diagnosis
MRI typically shows an enhancing, inflammatory lesion in the cavernous sinus and orbital apex. The lesion is hyperintense on T2-weighted images. Imaging findings are nonspecific, and it is a diagnosis of exclusion. In some patients, a biopsy may be needed to exclude neoplastic processes (lymphomas or meningiomas), which have a similar presentation.
Treatment
It is highly responsive, both clinically and radiographically, to corticosteroids. If there is no improvement, the diagnosis should be reconsidered. Immunosuppressive agents may be needed in treatment-refractory cases. It is recurrent after months to years in nearly half of the patients.
References
Case History
Diagnosis: Orbital Pseudotumor
Introduction
Idiopathic orbital inflammatory disease or orbital pseudotumor is an idiopathic inflammatory condition of the orbit. It most commonly involves the extraocular muscles, but may also affect the sclera, uvea, lacrimal glands, and retrobulbar soft tissue.
Clinical Presentation
Patients develop painful proptosis, redness, and diplopia. Symptoms develop rapidly and are unilateral in the vast majority of patients. It often occurs in conjunction with other autoimmune, inflammatory, or rheumatologic conditions.
A classification scheme has been proposed depending on which part of the orbit is most involved:
Radiographic Appearance and Diagnosis
Radiographic features depend on which part of the orbit is affected. For a myositis presentation, as depicted previously, imaging will reveal enlargement of one or more of the extraocular muscles. The muscles are slightly hyperintense on T2-weighted images and hypointense on T1-weighted images. There is often avid enhancement with the administration of contrast. In contrast to myositis associated with thyroid disease, the muscle tendons are affected.
It is a diagnosis of exclusion, once other causes have been ruled out.
Treatment
There is dramatic response to steroids, and the diagnosis should be reconsidered in patients who do not respond.
References
Case History
Diagnosis: Orbital Cavernous Venous Malformation
Introduction
Cavernous venous malformations of the orbit (also known as cavernous hemangiomas) are the slow-growing, benign, vascular lesions of the orbit. They are the most common vascular lesions of the orbit in adults, though overall, they are an uncommon finding.
Clinical Presentation
They most commonly present in middle-aged females with proptosis and double vision. Visual loss due to optic nerve dysfunction occurs in about one-third of patients. They may be found as incidental findings on imaging done for other reasons.
Radiographic Appearance and Diagnosis
MRI is the imaging modality of choice. These lesions are most commonly found in the lateral aspect of the intraconal space. They are well-circumscribed, round or oval, masses that are isointense on T1-weighted images and hyperintense on T2-weighted images. Contrast enhancement is common.
Treatment
Surgical removal of the lesion is curative. Incidental lesions may be monitored with clinical and radiographic monitoring.
References
Case History
Diagnosis: Dilated Perivascular Spaces—“Etat Crible”
Introduction
Perivascular spaces, also called Virchow–Robin spaces, are fluid-filled continuations of the subarachnoid space along the blood vessel walls that penetrate the base of the brain into the cerebral cortex and basal ganglia. Perivascular spaces play an important role in the maintenance of the blood–brain barrier and regulation of fluid drainage in the CNS.
Clinical Presentation
Enlarged perivascular spaces are common, particularly in elderly patients with hypertension. They may be enlarged to a diameter of 5 millimeters normally and are usually of no clinical consequence, though they can occasionally lead to hydrocephalus.
They can be seen as a feature of the mucopolysaccharidoses (Hunter and Hurler disease).
Radiographic Appearance
On MR imaging, dilated perivascular spaces are ovoid, cystic cavities that are most commonly bilateral and symmetric. They follow the appearance of CSF on all sequences and there is no mass effect, edema, calcification, or enhancement. They are categorized into three types:
They may be difficult to distinguish from lacunar infarctions; however, lacunar infarctions are more commonly located in the upper putamen, while dilated perivascular spaces are located in the inferior part.
In certain cases, innumerable dilated perivascular spaces take on a “colander-like” appearance condition, termed “etat crible.”
Treatment
There is no direct treatment beyond controlling hypertension and other vascular risk factors.
References
Case History
Diagnosis: Fibrous Dysplasia of the Skull,
Introduction
Craniofacial fibrous dysplasia is a congenital, idiopathic bone disorder, characterized by failure of the osteoblasts to undergo normal development and maturation. It can occur anywhere throughout the calvarium, though the anterior craniofacial bones are most commonly affected. The ethmoids are most commonly involved followed by the sphenoid frontal, maxilla, and temporal bones.
Clinical Presentation
It presents with headache and facial pain in teenagers and young adults. Craniofacial deformity and nasal stuffiness are common symptoms as well.
When there is involvement of the maxillary, sphenoid, ethmoid, and frontal bones, there is exophthalmos and decreased visual acuity due to involvement of the optic nerves. Involvement of other cranial nerves is common as well. Patients have a much higher likelihood of developing malignant bone tumors.
McCune–Albright syndrome is defined by the triad of fibrous dysplasia, café-au-lait skin macules with a “jagged coast of Maine” appearance, and endocrinopathies often leading to precocious puberty.
Radiographic Appearance and Diagnosis
On CT scans, the affected bones are expanded with a “ground glass” appearance. Though the bones are expanded, the cortex is intact.
Treatment
Surgery is reserved for symptomatic patients; however, complete resection is not possible.
References
Case History
Diagnosis: Hyperostosis Frontalis Interna/Morgagni–Stewart–Morel Syndrome
Introduction
Hyperostosis frontalis interna is a benign overgrowth of the inner side of the frontal bone of the skull. It is a not uncommon finding, seen mostly in women after menopause.
Clinical Presentation
It is usually asymptomatic and an incidental finding. However, it can be seen as part of Morgagni–Stewart–Morel syndrome. This rare syndrome also includes a variety of endocrinopathies (diabetes mellitus, diabetes insipidus, and hyperparathyroidism hirsutism, menstrual disorders, galactorrhea) as well as headaches, transient hemiparesis, obesity, vertigo, depression, and seizures.
Radiographic Appearance and Diagnosis
Imaging will show increased bone growth over the frontal lobes bilaterally.
Treatment
No treatment is necessary for incidentally discovered hyperostosis frontalis interna. The endocrine dysfunction of patients with Morgagni–Stewart–Morel syndrome requires treatment.
References
Case History
Diagnosis: Idiopathic Intracranial Hypertension
Introduction
The total volume of CSF is about 150 ml, and about 600 to 700 ml are produced daily. It is formed in the arachnoid granulations and flows through the foramens of Luschka and Magendie into the subarachnoid space, where it is reabsorbed into the venous system by the arachnoid villi. The normal intracranial pressure (ICP) is 5 to 15 mmHg.
Idiopathic intracranial hypertension (IIH) is due to either impaired absorption or increased production of CSF. It affects about 1 to 4 in 100,000 people.
It classically presents in young, overweight females. Various endocrinopathies, polycystic ovarian syndrome, excess vitamin A, and withdrawal from steroids are risk factors. It can occur in children and adults, and the average age of diagnosis is 30.
Clinical Presentation
Patients present with a throbbing headache over the entire head, which is often worse in the morning. Other symptoms include double vision, nausea, vomiting, and pulsatile tinnitus. Patients may have episodes of visual loss due to transiently increased ICP. These can be brought on by heavy lifting, laughing, sneezing, or coughing. Visual loss is the most feared complication and can occur as blind spot enlargement or visual field constriction.
Patients with increased ICP due to mass lesions have a similar presentation. It is for this reason that IIH is also known as pseudotumor cerebri.
Formal diagnostic criteria are known as the modified Dandy criteria:
Radiographic Appearance and Diagnosis
The classic imaging finding in IIH is a decrease in the size of the ventricles, described as “slit-like” ventricles, though imaging can also be normal. Another finding is the “empty sella” sign, where there is flattening of the pituitary gland due to chronic increased ICP. Other findings include distension of the optic nerve sheath subarachnoid spaces, tortuous optic nerves, and flattening of the posterior part of the globes. An MR venogram may reveal narrowing of the lateral portions of the transverse sinuses.
Fundoscopic examination is crucial in any patient with a complaint of headache. In patients with IIH, exam may reveal papilledema, which is defined as swelling of the optic disc due to increased ICP. Abducens nerve palsies are also common.
An LP demonstrating increased ICP is needed to confirm the diagnosis.
Treatment
Medical treatment includes acetazolamide, a carbonic anhydrase inhibitor, to reduce CSF production. Furosemide, a loop diuretic, may be added as well. Surgical intervention is used in treatment-refractory cases. This includes optic nerve sheath fenestration to relieve pressure on the optic nerve and shunting of the ventricular system. Ultimately, weight loss, including possible bariatric surgery, may be needed. Stenting of the venous system has shown success in some case series, but is not yet a standard treatment.
References
Case History
Diagnosis: Intracranial Hypotension
Introduction
Intracranial hypotension can occur after a lumbar puncture, trauma, neurosurgical procedures, or spontaneously due to a CSF leak in the subarachnoid space.
Clinical Presentation
It is characterized by an excruciating headache that is worsened when standing and relieved by lying down. Other symptoms include horizontal diplopia, vertigo, hearing loss, nausea/vomiting, visual loss or photophobia, and neck/interscapular pain.
Radiographic Appearance and Diagnosis
In patients with prolonged intracranial hypotension there is “brain sagging” with downward herniation of the cerebellar tonsils into the foramen magnum, flattening of the pons against the clivus, drooping of the splenium of the corpus callosum, and effacement of the basal cisterns. With the administration of contrast, the venous system is engorged and the transverse sinus is rounded and convex. This finding is known as the “venous distension” sign, and it is highly sensitive and specific for intracranial hypotension. These findings are best seen on sagittal MRI images. Other findings include brain edema and swelling of the pituitary gland. In severe cases, there may be subdural fluid collections.
In cases without a history known to produce intracranial hypotension, an LP can document the hypotension (less than 7 cm CSF). Spinal cisternography can be used to locate the site of the leakage.
Treatment
Many cases resolve spontaneously. Epidural blood patches are highly effective in relieving the headache in a majority of patients. In refractory cases with a defined leak, surgical repair may be required.
References
Case History
Diagnosis: Copper-Beaten Skull
Introduction
Any pathology that leads to an increased ICP can leave gyral impressions on the skull’s inner table. The resulting pattern appears similar to hand-worked metal and is referred to as a “copper-beaten skull.”
Clinical Presentation
The clinical presentation is related to the underlying cause. This can be obstructive hydrocephalus, craniosynostosis, or mass lesions.
It is usually seen in children, and, when localized to the posterior part of the skull, can occasionally be a normal finding.
Radiographic Appearance
Normally, the inner table of the skull is smooth. In some patients with severe, prolonged increased ICP, the skull develops a mottled appearance, known as a “copper-beaten skull,” reflecting the underlying gyri.
Treatment
The treatment depends on the underlying cause.
References
Case History
Diagnosis: Tension pneumocephalus, Mount Fuji Sign
Introduction
Pneumocephalus refers to gas, most commonly air, within the skull. The most common cause is traumatic injury, which results in a skull fracture and a tear in the dura. It may occur after surgical procedures, particularly those involving the paranasal sinuses. If the intracranial pressure is lower than the extracranial pressure, air flows into the intracranial compartment. Often, there is a ball-valve mechanism, and air can only flow inwards into the skull.
Clinical Presentation
Air acts like any other intracranial mass, producing symptoms of increased ICP (headache, nausea, vomiting) and focal neurological symptoms due to compression of the underlying brain.
Radiographic Appearance
CT scans are very sensitive for detecting even small amounts of air as it appears completely black. Fat has an identical appearance on soft tissue windows, but can be differentiated on bone windows or by measuring the Hounsfield units. It can be extraaxial, intraaxial, or intraventricular. A particular pattern of pneumocephalus involves compression of the frontal lobes. This is termed the “Mount Fuji sign” due to its resemblance to this Japanese mountain.
Treatment
Tension pneumocephalus is a neurosurgical emergency where release of the air and repair of any cranial defect are required. In contrast, small amounts of air are expected after neurosurgical procedures.
References
Case History
Diagnosis: Cervical Spondylotic Myelopathy
Introduction
Cervical spondylotic myelopathy (CSM) is the most common spinal cord disorder in older adults. Spondylosis refers to the degenerative changes that occur in the spine, and myelopathy due to narrowing of the spinal canal is known as spondylotic myelopathy.
Clinical Presentation
Patients present with the gradual onset of leg weakness and stiffness with difficulty walking. They also have neck stiffness and the insidious onset of pain in the neck, subscapular region, and shoulders, often radiating to the arms and hands. Bladder urgency, frequency, and/or retention, and weakness of the upper extremities may be seen in severe, longstanding cases.
Neurological exam will reveal weakness and spasticity of the legs, and weakness and atrophy of the hands and arms in advanced cases. Patients will be hyperreflexic with pathological reflexes (ankle clonus, Babinski sign, Hoffman’s sign). The gait will be spastic, and this is sometimes referred to as a “scissoring” gait as patients appear to walk with their legs crossing each other. There will be a variable and asymmetric pattern of sensory abnormalities. Sensory loss may follow dermatomal distribution, while other patients have a sensory level.
Radiographic Appearance and Diagnosis
MRI is the imaging modality of choice. It will reveal narrowing of the spinal canal with the absence of the normal CSF around the spinal cord. The cord itself is compressed and distorted. There is often intrinsic hyperintensity within the spinal cord on T2-weighted images. It is important to note that enhancement can be seen due to CSM. It is most common at the C5–C6 levels.
Treatment
Surgical decompression of the spinal cord is necessary once frank myelopathy occurs.
Medical therapies include: cervical immobilization (collar or neck brace), cervical traction, skull traction, and physical therapy.
Case History
Diagnosis: Disc Herniation
Introduction
A herniated disc occurs when there is displacement of material, typically the nucleus pulposus, with mass effect on the spinal cord or spinal nerve roots as they enter the intervertebral foramen. A tear in the outer, fibrous ring of an intervertebral disc allows the central portion to herniate out of the damaged annulus fibrosus. Contained herniations occur when the outer fibers of annulus fibrosus and posterior longitudinal ligament are intact. In contrast, with herniations that are not contained, there is a tear of outer fibers of annulus fibrosus and posterior longitudinal ligament (Illustration 15.15.1).
Additionally, cartilage, fragmented bone, and annular tissue may also herniate.
Displacements less than 25% of the disc circumference are called focal herniations, while those between 25% and 50% of the disc circumference are called “broad-based” (Illustration 15.15.2).
There are four locations for disc herniations (Illustration 15.15.3):
Compression or irritation of a nerve root as it exits the spine is known as a radiculopathy. This occurs most often in the cervical and lumbar portions of the spine due to the mobility of the neck and lower back. Cervical disc herniation most commonly occurs between C5 and C6 or C6 and C7 vertebral bodies. In the lumbar spine, herniations most commonly occur between L4 and L5 or L5 and S1 vertebral bodies.
In contrast to herniations, disc bulges involve over 25% of the circumference of an intervertebral disc. They occur gradually and are a near universal radiographic feature in older individuals.
Clinical Presentation
The symptoms of a herniation vary depending on which nerve root is affected, but most commonly include, pain (local or radicular), weakness, and numbness and tingling along the course of the nerve. The neurological examination similarly varies depending on which nerve is affected, but includes: sensory loss in the distribution of a nerve root; and weakness and atrophy of muscles innervated by the compressed nerve in more severe cases. Diminished or absent reflex can be seen as well. Specific symptoms of cervical radiculopathies are as follows:
C5: pain and weakness in the shoulders and upper arms
C6: pain along the lateral aspect of the forearm and thumb, weakness of the biceps, wrists, thumb, and index finger
C7: pain from the neck to the middle of the hand and triceps weakness
C8: pain from the neck to lateral aspect of the forearm and hand, weakness in hand grip
In the lumbar region, the sciatic nerve is the most commonly affected nerve, causing unilateral pain shooting down the back on one leg.
In adults, the spinal cord ends in the upper part of the vertebral column. The cauda equina (or “horse’s tail”) contains about 10 nerve fiber pairs, (five lumbar, five sacral, and a single coccygeal nerve). Compression of these nerves, often by a herniated disk at L4–L5 or L5–S1, causes a constellation of findings known as the cauda equina syndrome. These are:
Localized low back pain with or without unilateral or bilateral sciatica (radicular pain). In some patients pain may be completely absent.
Numbness in the genitals, buttocks, and anus due to compression of the sacral nerve roots. This pattern is often termed saddle anesthesia.
Lower extremity weakness, which is often asymmetrical.
Absent or diminished knee or ankle jerks, and diminished bulbocavernosus reflexes.
Loss of anal sphincter tone and anal wink.
Bowel and bladder dysfunction (typically, urinary manifestations begin with retention and are later followed by an overflow incontinence); constipation.
Radiographic Appearance and Diagnosis
MRI is the imaging modality of choice. It will reveal the disc herniation and demonstrate any compression of the spinal cord, nerve roots, or cauda equina.
Treatment
Cervical radiculopathies are initially treated with NSAIDs, muscle relaxants, and physical therapy. For severe pain, steroid injections may provide further relief. Surgical removal of the disc (discectomy) is an option for those with symptoms that are refractory to medical management.
In contrast, cauda equina syndrome (CES) is a neurosurgical emergency. Urgent surgical decompression of any herniated disc is indicated as soon as possible.
References
Case History
Diagnosis: Ankylosing Spondylitis
Introduction
Ankylosing spondylitis (AS), a spondyloarthropathy, is a chronic, multisystem inflammatory disorder primarily involving the sacroiliac (SI) joints and the axial skeleton. There is a strong association in patients who are HLA-B27 positive, which is seen in about 90% of affected individuals. Patients are usually younger than 40 and have symptoms for over 3 months. It is more common in men than women.
Clinical Presentation
Patients present with the insidious onset of low back pain and stiffness. The symptoms are worse in the morning or with inactivity. There is improvement with exercise. In severe cases, a persistently flexed posture may lead to dyspnea. Patients are at increased risk of death from cardiovascular disease.
Radiographic Appearance and Diagnosis
In AS, there is ossification of the outer rim of the annulus fibrosus of the intervertebral discs. This leads to marginal syndesmophytes (bony growths that develop inside a ligament) and vertebral body fusion, which in turn creates the characteristic “bamboo spine.”
Involvement of the SI joint, which is most often seen on conventional x-rays, is mandatory for the diagnosis of AS. Imaging of the SI joints, spine, and peripheral joints may reveal evidence of early sacroiliitis, erosions, and enthesitis.
Treatment
No definite disease-modifying therapy exists, although TNF-alpha inhibitors appear to have potential. Symptomatic management includes pain control, exercise, and physical therapy. Surgical intervention may be necessary to stabilize fracture and prevent neurological deficit.
References
Case History
Diagnosis: Tonsillar Herniation
Introduction
Herniation of the brain from one compartment to another usually occurs as a result of increased ICP. There are several patterns of herniation of both the supratentorial and infratentorial compartments. They are uncal (transtentorial), central, subfalcine, extracranial, upward, and tonsillar (Illustration 15.17.1).
Radiographic Appearance and Clinical Presentation
Uncal (Transtentorial) Herniation
It occurs due to a supratentorial mass or due to swelling after a large infarct or anoxic brain injury. There is downward displacement of medial brain structures through the tentorial notch. The innermost part of the temporal lobe, the uncus, herniates through the tentorium cerebelli.
The downward displacement puts pressure on the underlying structures, including the brainstem and upper cranial nerves. Compression of the corticospinal tract as it runs through the cerebral peduncle causes contralateral weakness. In certain cases, compression of the contralateral cerebral peduncle can cause ipsilateral weakness. This is a false localizing sign and is known as “Kernohan’s notch” phenomenon. The oculomotor nerve is frequently compressed as it emerges from the brainstem. As this is a compressive palsy, patients develop pupillary dilation prior to the ophthalmoplegia. Patients have usually suffered a devastating neurological event, and a “blown pupil” is often a sign of neurological decline. There can also be compression and infarction of the ipsilateral posterior cerebral artery (PCA).
Duret hemorrhages are small areas of bleeding in the midbrain and pons brainstem caused by downward displacement of the brainstem secondary to hippocampal gyrus herniation through the tentorial notch.
Central Herniation
A downward shift of the brainstem and the diencephalon due to a supratentorial mass. It results in Cheyne–Stokes respirations and pinpoint, nonreactive pupils.
Subfalcine (Cingulate) Herniation
Subfalcine (cingulate) herniation is a shift of the cingulate gyrus below the falx cerebri. This is the most common type of herniation pattern and is due to a mass in the frontal, parietal, or occipital lobes. Branches of the anterior cerebral artery may be compressed with subsequent infarction and contralateral leg weakness. There may be contralateral hydrocephalus if there is obstruction at the foramen of Monro.
Extracranial (Transcalvarial) Herniation
In extracranial herniation, the brain herniates through a defect in the skull, usually as a result of trauma or a neurosurgical procedure. In certain cases, such as lobar hemorrhages, subarachnoid hemorrhage, or malignant middle cerebral artery (MCA) infarcts, allowing for external herniation may be lifesaving, as it prevents other, fatal herniation syndromes. Similarly, patients with large cerebellar infarcts may occlude the fourth ventricle and suffer fatal obstructive hydrocephalus. A decompressive craniectomy may be lifesaving in such patients.
Upward (Transtentorial) Herniation
Mass effect in the posterior fossa can cause the cerebellum and midbrain to move superiorly through the tentorial opening.
Tonsillar Herniation
In tonsillar herniation there is protrusion of the cerebellar tonsils through the foramen magnum due to pressure in the posterior fossa. An example is shown in Images 15.17A–15.17C. Patients develop a headache and neck stiffness. Compression of the brainstem centers for respiration and cardiac function may result in cardiac or respiratory arrest. Blood pressure instability is common.
Reference
Case History
Diagnosis: Brain Death
Introduction
Brain death is defined as the complete and irreversible loss of functions of the brain and brainstem. Brain dead patients are clinically dead, though other organs may continue to function only with mechanical support.
Clinical Presentation
Establish irreversible and proximate cause of coma by history, examination, and neuroimaging. The presence of a CNS-depressant drug must be excluded. There should be no severe electrolyte, acid–base, or endocrine disturbances.
Core temperature must be normal.
Achieve normal systolic blood pressure.
Perform neurological examination confirming:
Patients should not respond to noxious stimuli, though spinal reflexes may be retained
Absence of pupillary response to a bright light in both eyes
Absence of ocular movements using oculocephalic testing and oculovestibular reflex testing
Absence of corneal reflex
Absence of facial movement to a noxious stimulus
Absence of the pharyngeal and tracheal reflexes
Absence of a respiratory drive is tested with a CO2 challenge. If respiratory movements are absent and arterial PCO2 is 60 mmHg or greater or there is a 20 mmHg increase above the baseline, the results support brain death.
Any physician may declare brain death, though certain specialties have more experience, and requirements may vary at different hospitals or in different states. In most cases, a single examination suffices, whereas some states and institutions require two different examinations by different doctors separated in time.
Radiographic Appearance
Though brain death is a clinical diagnosis, several tests can be used as confirmatory measures. These include electroencephalography, technetium 99m scans, transcranial Doppler ultrasonography, and cerebral angiography, though electroencephalogram is not routinely recommended due to frequency of artifact. These tests are not required and do not replace neurological examination.
With cerebral angiography, contrast is injected under high pressure in both anterior and posterior circulation. In brain dead patients, there will be no intracerebral flow, though there will be flow through the external carotid artery.
References
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