Fig. 12.1
The Frisén scale illustrating increasing grades of papilledema
Any patient with papilledema is at risk for vision loss and requires urgent evaluation. Often, papilledema is a sign of dangerous intracranial pathology that may require urgent neurosurgical intervention . Therefore, patients with papilledema should undergo urgent imaging of the brain and evaluation by an ophthalmologist or neuro-ophthalmologist. If the patient has other neurologic deficits associated with the papilledema, they should be referred to the emergency department for emergent imaging and evaluation. Those patients with mass lesions on neuroimaging should undergo neurosurgical evaluation on an urgent or emergent basis depending on location of the lesion, relationship to surrounding structures, and patient presentation.
Visual Function in Papilledema
Although most optic neuropathies lead to decreased acuity and color vision, these functions remain relatively spared in papilledema, as the maculopapillary bundle that carries central acuity and color data from the center of the retina, the fovea, remains relatively unharmed. Instead, papilledema typically leads to peripheral visual field defects. The earliest defect tends to be an enlargement of the physiologic blind spot, a small scotoma located approximately 15° temporal to fixation, which reflects the absence of the light-sensitive retinal cells (the rods and cones) at the location of the optic nerve head. Since papilledema results in separation of the retinal layers, and therefore retinal dysfunction in the region around the nerve head, the blind spot is enlarged. The superior disc is prone to edema in early papilledema, which may explain why field defects in the inferior nasal visual field also occur frequently in papilledema.
While early papilledema typically spares central vision, with time, peripheral field loss can progress, resulting in severe tunnel vision, and ultimately acuity and color vision can be lost. In rare cases of fulminant papilledema, acuity and color may be lost at presentation, signifying a neuro-ophthalmic injury that regardless of cause requires urgent reduction in ICP to try and prevent permanent injury to the optic nerve and central vision loss. Furthermore, some cases of papilledema are accompanied by the tracking of fluid to the fovea, in which case acuity is also reduced at presentation [7].
Causes of Papilledema in Children
Intracranial hypertension from any cause may result in papilledema. The differential diagnosis includes mass lesions, venous sinus thrombosis (VST) , craniosynostosis (premature closure of the skull sutures), aqueductal stenosis, and idiopathic intracranial hypertension. The presence of papilledema indicates only elevated ICP but there are no features of the disc appearance that can differentiate one cause from another. If papilledema is visualized, imaging of the brain with a contrast-enhanced MRI or CT scan is indicated to rule out a structural lesion or venous sinus thrombosis as the etiology, and evaluation by a neurologist and ophthalmologist is encouraged.
Aqueductal Stenosis
A common etiology of increased intracranial pressure in children is aqueductal stenosis , which refers to prevention of CSF outflow by a blockage at the level of the cerebral aqueduct. It may be associated with hydrocephalus, enlarged ventricles above the obstruction, and or peri-aqueductal edema within the midbrain. Aqueductal stenosis can be treated effectively with a ventriculoperitoneal shunt (VPS) allowing CSF to be redirected to the peritoneal cavity and relieving the pressure on the brain. Less commonly, a ventriculoatrial shunt is used. Endoscopic third ventriculostomy (ETV) is now the preferred treatment option [8] for pure aqueductal stenosis. ETV is a minimally invasive technique which obviates the need for placement of an indwelling shunt, minimizing risks including shunt infection, blockage, and breakage.
Mass Lesions
Pediatric papilledema may be the first or only sign of a mass lesion , such as a tumor, abscess, or hemorrhage. In children, most brain tumors are located in the posterior fossa, within the cerebellum or brainstem, [9] placing children at high risk for obstruction of the fourth ventricle and for elevated ICP. These include pilocytic astrocytomas, medulloblastomas, and brainstem gliomas.
Vignette 2
A 15-year-old boy presented to the emergency department with fever, headache, neck pain, and vomiting. Headaches were worse at night and when lying flat. The patient also noted binocular horizontal diplopia, and altered respirations. Neuro-ophthalmic examination revealed that he was unable to fully abduct his right eye. Intermittent episodes of apnea during sleep, bradycardia, and hypertension were observed. Dexamethasone and acetazolamide were started in an attempt to reduce intracranial pressure. MRI brain with and without gadolinium revealed a heterogeneously enhancing mass arising dorsal to the fourth ventricle with minimal surrounding vasogenic edema, partially obliterating the fourth ventricle, as seen in Fig. 12.2a. The tumor was resected and pathology was consistent with pilocytic astrocytoma , WHO grade I. Post-operatively, an external ventricular drain was placed and measured a mildly elevated intracranial pressure to the low 20s. Despite the mildly elevated pressures, the patient remained asymptomatic so his drain was clamped. Three weeks later, headaches, nausea, and vomiting recurred. He was referred to neuro-ophthalmology where a dilated fundoscopic examination revealed Frisén grade I papilledema and a mild abduction deficit in his left eye. The Frisén grade I papilledema is pictured in Fig. 12.2b, where arrows identify a blue halo associated with retinal nerve fiber layer thickening. The patient was monitored conservatively and 8 weeks later he was without headache, and the abducens palsy resolved. The decision to undergo shunt placement was deferred and he continued to improve clinically.
Fig. 12.2
Posterior fossa astrocytoma. (a) T1 weighted MRI brain with and without gadolinium reveals a heterogeneously enhancing mass arising dorsal to the fourth ventricle, partially obliterating the fourth ventricle. The patient’s exam revealed Frisén grade I papilledema (b). Arrows identify a blue halo associated with retinal nerve fiber layer thickening
As demonstrated above, papilledema is often accompanied by headache, nausea, or vomiting, and may be accompanied by other signs of elevated ICP including abducens palsies. The abducens or sixth cranial nerve is particularly vulnerable to injury by elevated ICP as it must ascend along the clivus bone before coursing above the clinoid process to enter Dorello’s canal and the cavernous sinus. With elevations in ICP, downward movement of the brainstem stretches the abducens nerve which is then compressed against the clinoid process. In this setting, the abducens palsy is a false localizing sign and may point the practitioner erroneously to the brainstem. This particular patient showed signs of Cushing’s triad of hypertension, bradycardia, and apnea, indicating a neurologic and neurosurgical emergency as it suggests imminent herniation.
MRI Findings Associated with Papilledema
While the funduscopic examination remains the gold standard to diagnosing papilledema, there are several associated MRI findings that may help confirm the finding or even indicate that a funduscopic examination is necessary. Radiographic papilledema is defined as flattening of the posterior sclera and enlargement of the perineural subarachnoid space, best seen on coronal T2 orbital MRI [10]. Increased ICP may also compress the pituitary gland inferiorly, leading to the appearance of an empty sella, and in some cases, the cerebellar tonsils may herniate a few millimeters below the foramen magnum. Figure 12.3c illustrates MRI findings typically found in association with papilledema.
Fig. 12.3
Papilledema and visual field loss in the setting of IIH and venous sinus thrombosis. (a) Humphrey visual fields demonstrate severely restricted fields, bilaterally. (b) Fundus photos illustrate Frisén grade 5 papilledema with loss of vasculature on the disc. (c) Sagittal MRI brain reveals signs indicative of elevated ICP. Yellow arrows illustrate the empty sella (S) as well as the downward tonsillar herniation (T) found in conjunction with elevated intracranial pressure. (d) Axial MRI with and without gadolinium with arrows identifying the thrombus in the superior sagittal sinus
Idiopathic Intracranial Hypertension
Idiopathic intracranial hypertension (IIH ) , previously called pseudotumor cerebri, is a disease of elevated ICP in the absence of any structural cause that typically presents in obese woman of childbearing age. It is of particular importance to the neurosurgeon since severe cases may be treated with neurosurgical procedures. Children with IIH are often not obese. Typical presenting symptoms include a positional headache worse when supine and in the morning, neck pain, horizontal diplopia from abducens nerve palsies, nausea, retrobulbar pain, pulsatile tinnitus, and visual loss when more severe [11]. Ophthalmologic examination usually reveals papilledema, and in many cases, an abducens nerve palsy. Visual field testing will usually reveal some degree of visual field constriction, typically an enlarged blind spot or inferior nasal defect. It is diagnosed only after excluding all other etiologies of increased intracranial pressure, such as mass lesions, aqueductal stenosis, and venous sinus thrombosis [10]. The modified Dandy criteria require the absence of localizing neurological findings (excluding abducens nerve palsies) and an elevated opening pressure in the absence of alternate causes on MRI [12]. Patients generally feel a dramatic but temporary relief of their headache after a large volume lumbar puncture.
As its name suggests, the etiology of IIH remains unclear, but its association with obesity in women suggests that weight-related elevation in intrathoracic venous pressure may play a role or that increased estrogen conversion by adipose tissue may lead to changes in the competence of the arachnoid granulations that absorb the CSF [13–15]. There is increasing evidence of a high frequency of non-thrombotic stenosis at the level of the transverse sinus-sigmoid sinus junction in patients with IIH. Whether this stenosis is a primary cause of IIH or is simply a consequence of secondary venous compression remains controversial [16].
Treatment of IIH
Management of these patients depends on the severity of symptoms, and most importantly, the degree of visual loss. Patients with spared vision, or with only mild deficits, can be managed medically with acetazolamide, topiramate, or furosemide in combination with an emphasis on weight loss. However, those patients who do not respond to medical therapy and those who have more severe disease sometimes need surgical intervention [11] to address vision-threatening increased ICP. Conventional options in such cases include the placement of a ventriculoperitoneal or lumboperitoneal shunt, optic nerve fenestration , or repeated lumbar punctures if surgical treatment is unavailable [10] or deemed too risky due to comorbidities. The high frequency of venous sinus stenosis in patients with IIH has resulted in the practice of stent placement within the venous sinus in some centers when conventional venography confirms the stenosis and shows an abnormally high pressure gradient across the stenosis. Retrospective series indicate improvement in IIH symptoms and papilledema in a majority of patients, and appear to remain patent for over 2 years [17] but prospective trials are lacking and this remains an experimental procedure [17, 18]. Experience in the pediatric population in particular remains quite limited.
Venous Sinus Thrombosis
Venous sinus thrombosis (VST ) is relatively rare in children, but may present with a syndrome of elevated ICP mimicking IIH. Important precipitants in children include meningitis, genetic thrombophilias, the use of oral contraception in teenagers, and prior manipulation of the venous sinuses. Patients with papilledema should always be evaluated for venous sinus thrombosis as it is a treatable condition with potentially severe effects on the brain and visual system.
Vignette 3
A 16-year-old young woman with increased body mass index presented to her local emergency department with severe holocephalic headaches that would wake her up from sleep. Head CT was unremarkable and she was discharged home. She presented to the ER 3 weeks later when blurry vision developed and she was evaluated by neuro-ophthalmology. Examination revealed visual acuity of 20/200 in the right eye and only the ability to count fingers in the left eye. She was unable to see any color plates and had severely restricted fields bilaterally (Fig. 12.3a), as well as Frisén grade 5 papilledema bilaterally. Figure 12.3b illustrates the Frisén grade 5 papilledema with loss of vasculature on the disc. An MRI of her brain revealed a partial empty sella and radiographic papilledema while MR venogram (MRV) ruled out VST. The patient’s MRI is shown in Fig. 12.3c, with yellow arrows illustrating the empty sella (S) as well as the downward tonsillar herniation (T) found in conjunction with elevated intracranial pressure. Lumbar puncture showed normal contents but an opening pressure >55 cm H2O. She was diagnosed with fulminant IIH and because of the profound vision loss, underwent VP shunt placement and treatment with acetazolamide. At discharge her vision had improved to 20/30 OD and 20/400 OS. One month later, severe headache and vomiting recurred. Examination revealed no improvement in visual fields or papilledema. MRV showed extensive thrombus of the superior sagittal sinus and bilateral transverse sinuses. In Fig. 12.3d, arrows identify thrombus in the superior sagittal sinus. She was started on therapeutic enoxaparin. Out of concern for infection, she underwent a repeat lumbar puncture which remained notable for elevated ICP, and cultures grew staphylococcus epidermidis. She was treated with antibiotics and her shunt was externalized and eventually revised. Despite improvement in headaches, a follow-up exam showed no visual improvement and the development of optic nerve atrophy. An optic nerve fenestration was performed on her right eye with improvement in her papilledema and some improvement in her visual field on the right. She subsequently underwent optic nerve sheath fenestration to the left eye.
This case demonstrates the potential of IIH to cause severe visual loss in critical cases, and the importance of early surgical intervention when acuity or serious visual field loss is present. Although the patient was left with significant acuity loss in her left eye, the placement of a VPS upon presentation may have avoided a similar fate to the right eye. Also highlighted is the potential for papilledema in cases of VST, as discussed above. This case is unique in that a VST appeared to supervene in a case of IIH. It remains unclear whether the VST was present all along but missed by the initial MRV or whether a secondary infection led to a septic VST. In any case of IIH where papilledema does not improve with placement of a VPS, the shunt should be interrogated and replaced if necessary, and repeat venous imaging should be considered to rule out an occult VST.
Craniosynostosis
Craniosynostosis refers to the aberrant fusion of cranial bones with loss of the normal sutures. This occasionally results in a small cranial vault. The etiologies for this are reviewed in detail in Chap. 6. In addition to varied types of cranial morphological complications already discussed in Chap. 6, craniosynostosis may also result in elevated ICP and thus papilledema. Any child with a history of rickets and papilledema should be investigated for hypophosphatemic rickets, which can lead to craniosynostosis due to abnormal suture formation [19]. Studies have shown that craniofacial surgery for craniosynostosis reduces preoperative papilledema [20].
Unilateral Papillitis
It should be noted that disc swelling may also be found in cases of inflammation, whether from autoimmune disease or infection, and more rarely, neoplastic infiltration. In such cases, there is typically acuity and color vision loss and the disc edema is often unilateral, helping to differentiate them from papilledema. Optic neuritis, a demyelinating inflammatory condition of the optic nerve, may cause disc edema in a minority of cases, but disc hemorrhages and cotton wool spots are absent, and the presentation is frequently associated with pain with eye movements.
Visual Field Defects
The early identification of visual field deficits can help the practitioner properly localize lesions of the central nervous system that may be amenable to neurosurgical resection. In many cases, timely management may help prevent further visual field loss or even reverse existing deficits. Monocular visual field defects suggest a lesion of the optic nerve or retina or a media opacity within the ocular structures. There are several patterns of visual field loss that suggest an optic neuropathy as the cause. First, a cecocentral scotoma , which stretches from the central region to the physiologic blind spot, tends to occur in cases where acuity is decreased, and reflects dysfunction of the highly metabolic fibers of the maculopapillary bundle which links the optic nerve to the fovea, the central region of the macula containing the highest density of cones. This is differentiated from the central scotoma of maculopathies that may have an irregular border. Ischemic causes of optic neuropathies typically cause altitudinal defects, meaning that either the superior half or inferior half of the visual field is lost. Arcuate scotomas are most often linked with glaucoma, but may occur in any optic neuropathy, and reflect injury to fibers temporal to the optic nerve that must arc around the fovea and maculopapillary bundle to reach the optic nerve head.
Chiasmal lesions tend to cause bitemporal hemianopsias, due to disruption of the nasal fibers as they cross within its body. Pituitary compression of the chiasm tends to cause a superior bitemporal hemianopsia early on, since the compression is from below, while superior tumors compressing the superior aspect of the chiasm (such as craniopharyngiomas) typically cause inferior bitemporal hemianopsias at first.
Retrochiasmatic lesions lead to contralateral homonymous (same side in both eyes), hemianopsias, or quadrantanopsias. This includes lesions of the optic tract, lateral geniculate nucleus of the thalamus, optic radiations of the parietal lobe (leading to an inferior homonymous field defect), Meyer’s loop of the temporal lobe (leading to a superior homonymous defect), and occipital lobe.
Vignette 4
A 9-year-old girl presented with ataxia and was noted to have left-sided hemi-atrophy. MRI revealed a right thalamic and midbrain tumor, pictured in Fig. 12.4a with arrows illustrating compression of the optic tract (OT) and the fourth cranial nerve (IV). Biopsy was consistent with a WHO grade I juvenile pilocytic astrocytoma (JPA). Neuro-ophthalmology was consulted because of vertical diplopia. On examination, she was found to have an incongruous left inferior quadrantanopia, pictured on humphrey visual fields in Fig. 12.4b, as well as a left relative afferent pupillary defect. Motility examination revealed a right hypertropia that was worse in left gaze and right head tilt, consistent with left fourth nerve palsy. Dilated funduscopy revealed temporal pallor of the right optic nerve and bowtie atrophy of the left. The bowtie atrophy is illustrated in Fig. 12.4c with arrows identifying the atrophied fibers.
Fig. 12.4
Compression of optic tract and fourth cranial nerve. (a) T1 weighted axial MRI reveal a right thalamic and midbrain tumor with arrows illustrating compression of the optic tract (OT) and the fourth cranial nerve (IV). (b) Humphrey visual fields demonstrate an incongruous left inferior quandrantanopia. (c) Fundus photography illustrates bowtie atrophy with arrows identifying the atrophied fibers
This case demonstrates several important neuro-ophthalmological examination findings . A left inferior quadrantanopia could reflect either a right superior occipital lobe lesion, a right parietal lobe lesion or right optic tract lesion, but multiple findings confirmed that the field loss localized to the optic tract. First, as can be seen in A, the defects are incongruous, meaning that the exact shape is different in the right and left eyes. This is more common in optic tract lesions since the fibers from the two eyes have not completely intermingled yet, although this point has been debated [21]. Second, cortical lesions causing a homonymous field defect would not cause any optic atrophy over time, since the nerve fibers of the optic nerve continue through the optic chiasm and tracts to synapse in the thalamus, but do not continue into the cortex. The type of atrophy seen in the eye contralateral to the lesion is in fact classic for optic tract lesions in that the temporal and nasal sides are pale, but the superior and inferior aspects of the nerve are relatively spared. This finding, referred to as “bowtie” or “band” atrophy, results from the fact that the retinal fibers destined to become part of the contralateral optic tract enter the optic nerve head from the nasal and temporal sides. As they atrophy, the corresponding parts of the disc become pale. Finally, the presence of left-sided RAPD implies a right optic tract lesion in the setting of the left homonymous defect. This finding occurs because of a slightly uneven splitting of each optic nerve at the chiasm so that the right optic tract actually contains more left optic nerve fibers than right. Its injury therefore will have a similar effect as a left optic nerve injury on the pupillary response.
Whenever a new homonymous visual field deficit is detected on examination, the patient should undergo urgent imaging with an MRI brain, and possibly an MR angiogram if this is unrevealing. Often, a mass lesion will be discovered which may require neurosurgical intervention.
Please see Fig. 12.5 for a review of pattern of field defects.
Fig. 12.5
Review of the afferent visual pathways and field defects corresponding to injury at each level. Red lines represent the pathways carrying right visual field information to the left occipital cortex and blue lines represent pathways carrying left visual field information to the right visual cortex. Dashed lines represent light rays landing on the retina. Thick black lines represent sites of injury corresponding to the visual field loss shown on the right. (A) Retinal disease affecting the macula tends to cause central scotomas, often in a geographic pattern, as seen in the right eye’s field, while peripheral retinal disease such as retinitis pigmentosa, typically causes a ring scotoma as seen in the left eye. (B) Optic neuropathies may cause altitudinal defects (seen in the left eye’s field) or cecocentral scotomas which are ovoid areas of blindness encompassing central fixation (plus sign) and the physiologic blind spot (this cecocentral scotoma is shown in gray to allow visualization of the physiological blind spot). (C) Disease of the optic chiasm typically causes a bitemporal hemianopsia. (D) Optic tract injury causes a contralateral homonymous hemianopsia, classically incongruous, meaning that the exact shape of the field defect is different in each eye. (E) A stroke to the lateral geniculate nucleus causes a contralateral sectoranopia, leading to loss either of the contralateral central third (posterior choroidal artery infarct, not shown) or the contralateral upper and lower thirds sparing the central third (anterior choroidal artery infarct, shown here). (F) Damage to Meyer’s loop, which travels in the temporal lobe, leads to a contralateral homonymous superior quadrantanopia. (G) Damage to the optic radiation, which travels in the parietal lobe, causes a contralateral homonymous inferior quadrantanopia. (H) Occipital lobe injury causes a contralateral homonymous hemianopsia which is typically congruous (meaning that the exact shape of the field loss is equal in each eye). In cases of occipital lobe stroke due to posterior cerebral artery occlusion, there may be “macular sparing” as shown here, due to redundant perfusion of the occipital pole by branches of the middle cerebral artery. If the anterior extent of the occipital cortex is spared, then there may be a spared temporal crescent in the eye ipsilateral to the field loss, as shown here, reflecting a region of cortex which receives monocular visual information from a crescent of vision seen only by the contralateral eye
Vignette 5
A 13-year-old boy with a history of Wolff-Parkinson-White syndrome treated with catheter ablation and amblyopia OD was noted by his pediatrician to have growth deceleration. Growth hormone stimulation testing was consistent with growth hormone deficiency. Gadolinium-enhanced brain MRI revealed a suprasellar mass involving the optic chiasm and hypothalamus, extending along the right optic nerve and into the right optic foramen, most consistent with a hypothalamic/chiasmatic glioma. In Fig. 12.6c, a sagittal contrast-enhanced MRI shows the suprasellar mass lesion. Figure 12.6d demonstrates coronal cuts of the sella, illustrating compression of the right optic nerve. He was referred to neuro-ophthalmology where formal visual field testing revealed a bitemporal hemianopsia , as seen in Fig. 12.6a. Funduscopic examination revealed optic nerve pallor and temporal atrophy bilaterally as visualized in Fig. 12.6b. He continues to be observed with serial MRIs and visual field testing and over the course of 1 year has shown no progression of his disease.
Fig. 12.6
Visual field loss and optic atrophy from optic chiasm glioma. (a) Humphrey visual field testing demonstrates bitemporal hemianopsia. (b) Fundoscopic examination reveals optic nerve pallor and temporal atrophy bilaterally. (c) Sagittal contrast-enhanced MRI illustrates a suprasellar contrast enhancing mass lesion. (d) Coronal MRI cuts of the sella illustrate compression of the right optic nerve
While most suprasellar tumors causing chiasmal compression are amenable to neurosurgical resection and should be referred for neurosurgical evaluation, it is crucial that optic chiasmal gliomas are recognized to avoid ill-advised attempts at potentially vision-threatening resection. Often, limited biopsies or tumor-associated cyst fenestrations can be offered to aid in oncologic decision making and optic apparatus decompression can be preformed when appropriate.
Related posts:
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
