Identifying the imaging finding

Correct Answer: Afferent pupillary defect

This cerebral angiogram shows an ophthalmic artery aneurysm pre- (left) and post-coiling (right).

Ophthalmic artery aneurysms most commonly present with visual manifestations of compressive optic neuropathy. Aneurysm occlusion can be achieved with endovascular or microsurgical techniques.

Neuro-ophthalmologic exam showed an afferent pupillary defect with a superotemporal visual field defect from pre-chiasmatic optic nerve compression. Post-coiling there was near resolution of the visual field defect.

Correct Answer: Buccal Space

This patient likely has orbital cellulitis, based on the region and visible inflammation. In terms of a source of infection, the buccal space is particularly. As shown in the image on the right, the buccal space contains the infraorbital foramen, providing direct access to the orbit. A molar infection can easily spread from the buccal space up to the orbit.

The submandibular space can become infected, resulting in cellulitis that can become deadly if the airway is obstructed.

Nasal concha infections can become infected, known as concha bullosa, resulting in sinusitis.

The supraorbital foramen contains the trigeminal nerve and would more likely result in sinusitis or neuralgia.

Correct Answer: See-saw nystagmus

Craniopharyngiomas are epithelial tumors arising from Rathke’s pouch. They may involve the hypothalamus and there is often associated pituitary hormone/ neuroendocrine disturbance. Visual symptoms include bitemporal hemianopia, optic neuropathy and in large tumors, see-saw nystagmus (alternating elevation and intorsion of one eye with depression and extorsion of the other eye).

This coronal T1w MRI brain with contrast (left) and sagittal T1w MRI brain with contrast shows a suprasellar mass measuring approximately 2.9 cm x 2 cm x 2.4 cm causing chiasmal compression. There is heterogeneous enhancement.

Neuro-ophthalmologic exam showed right optic neuropathy with bitemporal hemianopia. Treatment with subtotal resection followed by fractionated radiation therapy was recommended.

Correct Answer: Optic nerve hypoplasia

• Septo-optic dysplasia is a clinical diagnosis requiring at least 2 of the following features: optic nerve hypoplasia, pituitary hormone deficiencies and midline brain defects (agenesis of the septum pellucidum and/or corpus callosum).
• This coronal T2w MRI brain (left) shows absence of the septum pellucidum and hypoplasia of the optic chiasm. The hypoplastic optic chiasm is also shown on the sagittal T1w MRI brain (right).
• Neuro-ophthalmologic exam showed esotropia, nystagmus, and optic nerve hypoplasia. Endocrinologic assessment revealed growth hormone deficiency.

Correct Answer: Internuclear ophthalmoplegia

• The classic sign of a medial longitudinal fasciculus lesion is internuclear ophthalmoplegia which consists of impaired adduction of the ipsilateral medial rectus muscle and contralateral abducting nystagmus.
• This axial T2 FLAIR MRI (left) and axial T1w MRI with contrast (right) shows a T2 hyperintense lesion of the medial longitudinal fasciculus with associated enhancement. MRI also showed several foci of T2 FLAIR hyperintensity throughout the white matter with a few lesions demonstrating enhancement compatible with active demyelination.
• Neuro-ophthalmologic exam showed a bilateral (left >> right) internuclear ophthalmoplegia with mild exotropia and left hypertropia (skew deviation) on right gaze and upbeat nystagmus on upgaze (due to vestibular fibers in MLF).

Correct Answer: Decreased facial sensation, CN VI paresis, and CN VII palsy

• Juvenile pilocytic astrocytomas are prevalent primary tumors in children and adolescents. They often occur in the optic nerve, hypothalamus, brainstem and cerebellum.
• This sagittal (left) T1w MRI with contrast and fat suppression and axial (right) T1w MRI with contrast shows a large multilobulated, solid and cystic tumor in the pons and medulla consistent with pilocytic astrocytoma.
• Neuro-ophthalmologic exam showed left-sided decreased facial sensation, facial weakness and CN VI paresis.

Correct Answer: Bilateral CN IV paresis

• Trochlear nerve schwannomas are benign tumors arising from Schwann cells of peripheral nerves. They more commonly arise from the trigeminal or vestibular nerves. Development of multiple schwannomas raises the possibility of underlying neurofibromatosis. Trochlear nerve schwannomas may be observed or treated with microsurgical resection or stereotactic radiosurgery.
• This axial T1w MRI with contrast shows focal enlargement and enhancement along both cranial nerve IV consistent with bilateral trochlear nerve schwannomas.
• Neuro-ophthalmologic exam showed bilateral CN IV pareses.

Correct Answer: Bitemporal hemianopia

• Pituitary adenomas are the most common sellar tumors. Pituitary macroadenomas (> 10 mm) causing peripheral vision loss are typically treated with transsphenoidal resection except for prolactinomas which are usually treated with bromocriptine or cabergoline.
• Sagittal T1w MRI with contrast (left) and coronal T1w MRI with contrast (right) show a 3.5 cm pituitary macroadenoma with compression of the optic chiasm and extension to right cavernous sinus.
• Neuro-ophthalmologic exam showed a compressive left optic neuropathy and bitemporal hemianopia. Despite right cavernous sinus extension radiologically, there was no ocular misalignment on exam.
• Tritos NA, Miller KK. Diagnosis and Management of Pituitary Adenomas: A Review. JAMA. 2023;329(16):1386–1398.

Correct Answer: Optic neuropathy and CN III and CN VI pareses

• Cavernous sinus meningiomas are benign, slow growing tumors that typically cause ophthalmoplegia but may impact afferent visual function with optic nerve or chiasm compression. Treatment may include surgery in select cases or radiation therapy.
• Coronal T1 with fat suppression and contrast (left) and axial T1 MPRAGE with contrast (right) showed a 4 cm enhancing dural-based lesion centered in right cavernous sinus, consistent with meningioma, extending to right orbital apex.
• Neuro-ophthalmologic exam showed a right compressive optic neuropathy, right pupil-involving partial CN III paresis and right CN VI paresis.
• Hekmatpanah J. Evidence-based treatment of cavernous sinus meningioma. Surg Neurol Int. 2019 Nov 22;10:228.Hasegawa T, Kida Y, Yoshimoto M, Koike J, Iizuka H, Ishii D, et al. Long-term outcomes of gamma knife surgery for cavernous sinus meningioma. J Neurosurg 2007;107:745-51.

Correct Answer: Convergence-retraction nystagmus

• Adult brainstem gliomas are rare (<2% of gliomas). Presenting symptoms include imbalance, ataxia, lower extremity weakness and binocular diplopia. Prognosis is poor for high grade brainstem gliomas despite radiation therapy and chemotherapy.
• This sagittal (left) and axial (right) T1 with fat suppression and contrast MRI shows an enhancing lesion in left midbrain concerning for glioma at site of prior hemorrhage.  There is surrounding vasogenic edema and effacement of cerebral aqueduct and third ventricle.
• Neuro-ophthalmologic exam showed light-near dissociation, Cogan lid retraction, upgaze palsy, convergence-retraction nystagmus on attempted upgaze and skew deviation. These findings are consistent with dorsal midbrain syndrome.
• Guillamo JS, Monjour A, Taillandier L, Devaux B, Varlet P, Haie-Meder C, Defer GL, Maison P, Mazeron JJ, Cornu P, Delattre JY; Association des Neuro-Oncologues d’Expression Française (ANOCEF). Brainstem gliomas in adults: prognostic factors and classification. Brain. 2001 Dec;124(Pt 12):2528-39.

Correct Answer: Optic neuropathy with left homonymous hemianopia

• Optic pathway gliomas are low grade astrocytomas often involving the hypothalamus. They usually present in childhood and can occur in association with neurofibromatosis type I.
• This sagittal cube FLAIR (left) and axial T1 with contrast (right) MRI shows a 2 cm mass with solid and cystic components arising from the right optic tract and chiasm with extension into the hypothalamus. There is resultant obstructive hydrocephalus.
• Neuro-ophthalmologic exam showed bilateral optic atrophy with a left homonymous hemianopia. There was no papilledema. Patient underwent VP shunt placement and otherwise elected observation.
• Walker DA, Aquilina K, Spoudeas H, Pilotto C, Gan HW, Meijer L. A new era for optic pathway glioma: A developmental brain tumor with life-long health consequences. Front Pediatr. 2023 Mar 24;11:1038937

Correct Answer: Bilateral optic neuropathy and bitemporal hemianopia

• Planum sphenoidale meningiomas enlarge slowly displacing the frontal lobes and causing optic chiasm compression.
• The sagittal and coronal T1 FLAIR MRI with fat suppression and contrast show a large planum sphenoidale meningioma which caused slowly progressive bilateral vision loss and change in personality. Neuro-ophthalmologic exam showed bilateral compressive optic neuropathy with bitemporal hemianopia due to chiasmal compression. There was significant visual recovery with resection and radiation therapy.
• Echalier EL, Subramanian PS. Meningiomas of the planum sphenoidale and tuberculum sella. J Neurol Surg B Skull Base. 2021 Feb; 82(1): 72-80.

Correct Answer: Upwardly displaced posterior pituitary bright spot

• You are looking at a small (hypoplastic) optic disc. In other words, the optic nerve has too few axons, a congenital defect. Hypoplastic optic discs are manifestations of a forebrain dysgenesis, which may include the hypothalamic-pituitary axis. The MRI sign that best predicts hormonal dysfunction, which can be life-threatening, is the displacement of the normal posterior pituitary “bright spot” seen on the pre-contrast T1-weighted sagittal pulse sequence. It should normally be found in the posterior portion of the pituitary gland in the sella turcica. If you find it up in the hypothalamus,
• alert the pediatrician to the fact that the patient may not be able to mount an adequate hormonal response in a febrile illness.

Correct Answer: Diabetic papillopathy

• This is a difficult diagnosis to make. First, decide if the bilateral optic disc elevation is congenital or acquired—not always easy on ophthalmoscopy alone. Preservation of the physiologic cup with elevation and obscuration of the peripapillary nerve fiber layer are clues to acquired optic disc elevation; so are papillary or peripapillary hemorrhages. Second, decide among various causes of acquired bilateral optic disc elevation, which conveniently start with the letter “i:” inflammation, ischemia, increased intracranial pressure (papilledema), increased systemic blood pressure (hypertensive optic disc edema), increased retinal venous pressure (retinal vein occlusion), inherited disorders (Leber hereditary optic neuropathy), intoxications (toxic optic neuropathy), and finally intolerance to glucose (diabetes mellitus). Inflammatory optic disc elevation usually causes leakage on fluorescein angiography; so does papilledema, although minimally. The preservation of visual acuity largely excludes LHON and intoxication; it does not entirely exclude ischemic optic neuropathy, which often spares the maculopapillar axons, but simultaneous binocular occurrence is unusual in that condition. Central retinal vein occlusion can cause considerable optic disc elevation, but engorged retinal veins and perivenous hemorrhages should also be present. Hypertensive optic disc edema is often binocular, but signs of retinal arterial occlusive disease should be evident. That leaves papilledema as the rule-out diagnosis, for which you will be impelled to order brain imaging; if negative, lumbar puncture will be next. If brain imaging and lumbar puncture are negative, you will fall back on a diagnosis of diabetic papillopathy.

Correct Answer: No intervention

The imaging features and the patient’s age strongly suggest a diagnosis of pilocytic astrocytoma (“optic glioma”), a World Health Organization Grade 1 (low malignant potential) lesion limited to the orbital segment of the nerve. He may have neurofibromatosis type 1 (NF 1). There is no evidence that surgery on such a lesion prevents spread to the optic chiasm, hypothalamus, or other optic nerve. Whether to undertake chemotherapy for a lesion confined to one intra-orbital optic nerve is controversial. Many oncologists would defer because anecdotal evidence of benefit is weak and there are no controlled clinical trials. Current regimens, which are vinca alkaloid and platinum-based, are safe but arduous. There is suggestive evidence that checkpoint inhibitors may be more effective. Radiation therapy is not supported by trial evidence and is especially toxic. If serial clinical and imaging examinations were to suggest the development of binocular vision loss or imaging involvement of both optic nerves, the optic chiasm or the hypothalamus, then chemotherapy would be a more viable consideration. Investigation for non-ophthalmic signs of NF 1 is reasonable.

Correct Answer: Hemorrhagic pituitary adenoma

The arrow is pointing to an area of high signal on this sagittal pre-contrast T1-weighted MRI scan. That white area lies within a mass that appears to arise within the sella turcica. No separate pituitary gland is visible, so likely the mass is the pituitary gland itself—a pituitary adenoma. Bright signal on pre-contrast T1 MRI can be caused by fat, protein, some forms of calcium, melanin, slowly-flowing intravascular blood, and methemoglobin from fresh extravascular blood. In this case, it is extravascular blood within the pituitary gland, a phenomenon called “pituitary apoplexy.” Do not confuse this phenomenon with the pituitary infarction that occurs after pregnancy (Sheehan syndrome). Pituitary apoplexy is bleeding without infarction. The bleeding may expand the gland to cause pressure on the diaphragma sellae (headache), on the optic chiasm (bitemporal hemianopia), or on the cavernous sinus (ophthalmoplegia). Transsphenoidal surgery is usually performed promptly, often with excellent restoration of vision and normal ocular alignment.

Correct Answer: Recurrent vision loss is more often due to growth of cysts than of solid tumor

Craniopharyngiomas are made up of congenital cell rests that normally line the throat. These cell rests find their way into the middle cranial fossa and generate solid and cystic masses. Although extensive surgical removal is important, complete excision is dangerous to vision. High-dose x-irradiation is critical to prevent regrowth, but it works best if much tumor has already been removed. Craniopharyngiomas grow upwards to block the foramen of Monro, causing hydrocephalus that often requires ventriculo-peritoneal shunting. In spite of extensive surgery and radiation, cystic regrowth is common and causes rapid loss of vision. The cysts must be approached surgically.

Correct Answer: Initiate a two-week trial of oral prednisone 1/2mg/kg; if there is no improvement in visual function, refer for x-irradiation of the orbital lesion

The imaging features here suggest either an optic nerve sheath meningioma, a chronic dural inflammation (“pachymeningitis”), or lymphoma. You could order a CT scan, looking for calcium in the lesion, which would favor meningioma. You could look for inflammation or lymphoma elsewhere in the body with “pan CT scanning.” If a trial of prednisone improves vision, you would effectively exclude meningioma. In that case, additional imaging would be indicated to try to distinguish between the other options. X-irradiation of optic nerve sheath meningioma probably reduces the chances of lesion growth and further vision loss, and may even improve vision, but is not recommended if vision has already been severely compromised. Tip: do not recommend x-irradiation to prevent growth of an intracranial component because lesions that originate in the orbit almost never show sufficient intracranial growth to damage the other optic nerve or optic chiasm. Biopsy of this lesion is not advised because it is certain to damage vision. Recommend it only if all vision has been lost for many months and diagnosis is in doubt. Observation is an option if the patient refuses treatment despite understanding that x-irradiation is probably beneficial and has a low risk of harm. If x-irradiation is to be carried out, however, make sure that it is done in a center with experience treating such lesions, otherwise radiation toxicity to the retina, optic nerves, and optic chiasm is a serious risk!

Correct Answer: Radiation-induced optic neuropathy

• This MRI is showing a discrete area of enhancement in the prechiasmatic (intracranial) right optic nerve.
• Although such signal changes do occur here in optic neuritis, their location is typical for radiation-induced optic neuropathy. Moreover, the timing is perfect for this condition, which is based on endothelial damage and secondary infarction. Neither neoplastic nor paraneoplastic optic neuropathy shows such a discrete MRI signal abnormality. Radiation-induced optic neuropathy is a rare event when proper radiation protocols are conducted, but patients with underlying vasculopathy (neurofibromatosis, diabetes, hypertension) are at higher risk. Although hyperbaric oxygen and anticoagulation treatments are often proposed, they have never been shown to be effective. Unfortunately, stepwise decline in vision often occurs, sometimes involving both optic nerves.

Correct Answer: Bilateral ischemic optic neuropathy

The diffusion-weighted MRI is showing increased signal in both optic nerves, an indication of recent infarction. The cause was probably intra-operative systemic hypotension, which sometimes occurs accidentally or deliberately (to reduce hemorrhage that interferes with the surgeon’s view in the operative field). Called “peri-operative ischemic optic neuropathy” or “hypotensive ischemic optic neuropathy,” its mechanism is believed to be lack of perfusion of the intra-orbital optic nerve. The patient usually notices the vision loss upon regaining full consciousness, although it may initially be attributed to sedating analgesics. The radiologist’s attention should be drawn to the optic nerves and diffusion-weighted imaging should be included in the MRI study. Maintaining normal post-operative blood pressure is a reasonable gesture. Hyperbaric oxygen treatment and corticosteroids, often proposed, are not effective. Vision may spontaneously improve somewhat if the infarction has not been severe. Bilateral optic neuritis is not a favored diagnostic choice in this setting. Chiasmal infarction is rare and found in the postpartum state. Although visual cortex infarction can certainly occur in this setting, the afferent pupil defect in this case points to an optic nerve localization.

Correct Answer: High-dose corticosteroid treatment, followed by temporal artery biopsy

• You are looking at pallid swelling of both optic discs in a patient with a report of newly and severely reduced vision in both eyes. Bilateral simultaneous optic disc swelling often prompts consideration of papilledema from increased intracranial pressure, but papilledema does not usually cause such severe vision loss acutely. Moreover, the optic disc swelling here is pallid, therefore likely ischemic. Yes, she lacks systemic manifestations of giant cell arteritis (although the NSAID medication may be masking them) and does not have elevated acute phase reactants, but the fact that both optic discs are affected SIMULTANEOUSLY nearly excludes non-arteritic ischemic optic neuropathy and demands prompt exclusion of giant cell arteritis. (Giant cell arteritis may sometimes occur without any systemic symptoms and with normal serum acute phase reactants!) Therefore, she must undergo immediate corticosteroid treatment to help protect her against further vision loss, followed by temporal artery biopsy as soon as possible. The pathologist will be looking for thickening and inflammatory destruction of the vascular media–intima junction, fragmentation of the internal elastic lamina, and/or Langerhans giant cells.
• If biopsy of one side is negative and giant cell arteritis remains a prime suspect, you should consider a biopsy of the other side, which improves the detection rate of giant cell arteritis from 93% to 96%. Optical coherence tomography contributes nothing here. Fluorescein angiography in this setting might be useful to detect choroidal ischemia, a feature of giant cell arteritis, but you would proceed toward excluding giant cell arteritis even if it were negative. Were a double biopsy to be negative, a positive fluorescein angiogram might induce you to treat for giant cell arteritis in spite of the otherwise negative studies.

Correct Answer: Ambulatory blood pressure monitoring

This patient has the profile of optic disc stroke, also called “ischemic optic neuropathy.” Nothing in his history suggests that this is “arteritic,” even though that is always a concern. Temporal artery biopsy, preceded by high-dose corticosteroid treatment, is not medically justified here. You can comfortably diagnose “non-arteritic ischemic optic neuropathy,” which is generally caused by in situ compromise of tiny optic disc pre-capillary arterioles. Thus, carotid artery imaging is not indicated and neither is cardiac echography. Optic coherence tomography contributes nothing here. Ambulatory blood pressure monitoring may guide in establishing a proper blood pressure control regimen.

Correct Answer: Perifoveal yellow exudates may become more apparent

• You are looking at a swollen left optic disc. At this patient’s young age, the mechanism is probably inflammation, and the condition is labeled “papillitis.” It is a form of primarily intraocular (rather than retrobulbar) optic neuritis. Because trigeminal afferents do not penetrate that part of the optic nerve, there is no periocular pain. Brain/orbit MRI may show enhancement of the optic disc and sometimes intraorbital parenchymal or dural enhancement of the optic nerve. Perifoveal yellow exudates (“macular star figures”)
• often become more apparent within 2 weeks after clinical onset, reflecting the intense leakage of papillary capillaries, and generating the label “neuroretinitis,” although this condition is not really a retinal inflammation. Multiple sclerosis does not develop. An evaluation for systemic infectious (including syphilitic) and non-infectious inflammatory disorders is reasonable, but often no cause is found. Cat scratch disease may be diagnosed if a positive Bartonella serum antibody turns up. Most patients who have no signs of infection are treated with corticosteroids, although no controlled trials exist to prove benefit. Substantial visual recovery occurs without treatment in 50% to 75% of cases.

Correct Answer: Serum myelin oligodendrocyte glycoprotein antibody

The clinical and imaging features strongly suggest myelin oligodendrocyte glycoprotein (MOG) antibody-associated optic neuritis. The orbit imaging shows longitudinally-extensive enhancement and thickening of the optic nerve dura, which is characteristic of MOG optic neuritis. The scattered high T2/FLAIR cerebral white matter signal abnormalities could reflect acute disseminated encephalitis, which has been associated with the MOG antibody. The aquaporin-4 antibody is found in neuromyelitis optica (NMO, Devic disease), which also displays longitudinal enhancement along the course of the optic nerve, but within the nerve substance itself, rather than within its dural covering. Cerebrospinal fluid NMO and MOG are not helpful in diagnosis. In this patient, if the MOG antibody were normal, you would have to consider a wide variety of infectious and autoimmune conditions, demanding a thorough evaluation.

Correct Answer: Optic pit

This cavity in the inferior portion of the optic disc is a congenital anomaly, perhaps a mild form of optic disc coloboma. Because the cavity has no retinal ganglion cell axons, the patient will manifest a corresponding nerve fiber bundle visual field defect, which may be the abnormality that brings this condition to medical attention. Often confused with glaucoma, it may generate fruitless intraocular pressure-lowering treatment. The cavity and the visual field are stationary. There may be an associated serous detachment of the macula.

Correct Answer: Cerebellopontine Angle Schwannoma

• The most common cerebellopontine angle tumors are vestibular schwannoma (75-85%), meningioma (10-15%), and epidermoid tumors (<10%). CPA schwannomas can be sporadic or associated with neurofibromatosis type II, in which case they are usually bilateral.
• This coronal T1w MRI brain with contrast (left) and axial T1w MRI brain with contrast (right) shows a large heterogeneously enhancing mass with non-enhancing cystic foci centered upon the right cerebellopontine angle measuring 4.5 cm. There is encasement of the right cranial nerves VII and VIII complexes. There is also mass effect on the pons, displacement of the right cranial nerve V complex and mass effect on the right cerebellar hemisphere.
• Neuro-ophthalmologic exam showed right cranial nerve V, VI, VII and VIII palsies.

Correct Answer: Bruch’s membrane

Bruch’s membrane is a specialized five-layered structure located between the retinal pigment epithelium and the fenestrated choroidal capillaries in the eye. It is made up of an extracellular matrix rich in elastin and collagen and serves as a molecular sieve. In fact, all the other answers are one of the layers of retina.

Correct Answer: Posterior hyaloid membrane

Hyaloid membrane, also called the vitreous membrane or vitreous cortex, is a collagen layer that divides the vitreous humor from the retina. The posterior hyaloid membrane, which separates the rear of the vitreous from the retina, is considered a false anatomical membrane.

On the other hand, premacular bursa is optically empty space above the retina.

Correct Answer: Scleral crescent

Scleral and choroidal crescents generally appear on the temporal side of the optic disc and are harmless anatomical variations. A scleral crescent forms when the retinal and choroidal tissues do not directly connect to the optic nerve head, allowing the sclera to be seen directly.

Itis not pigment crescent because pigment accumulation seen at the disc margin in case of pigment crescent.

Correct Answer: Lamina Cribrosa

The lamina cribrosa is a mesh-like structure located in the back part
of the scleral canal of the optic nerve head. It allows retinal ganglion
cell axons to travel to the brain. This fenestrated structure also
contains vessels that supply nutrients to the retina.

It can be confused with the cribriform plate but it is a portion of the
ethmoid bone located at the base of the skull. The base of the skull is
the term used to describe the most inferior portion of the skull.

Correct Answer: Cilioretinal Artery

The cilioretinal artery actually is coming from the ophthalmic, but it’s like a posterior ciliary branch that comes out through the nerve head and is supplying a piece of the retina. Additionally, cilioretinal arteries found in 20-40% of the normal population.

MengJ, WeiL, Zhang K, He W, Lu Y, Zhu X. Cilioretinal Arteries in Highly Myopic Eyes: A Photographic Classification System and Its Association With Myopic Macular Degeneration. Front Med(Lausanne). 2020;7:595544. doi:10.3389/fmed.2020.595544