Clinical Reasoning: A 32-Year-Old Woman With Tunnel Vision and Back Pain

Section 1

A 32-year-old right-handed woman presented to clinic for bilateral visual disturbances described as episodes of transient tunnel vision lasting seconds. This progressed over weeks to include a persistent bilateral visual impairment described as peripheral visual darkening. The episodes were associated with pulsatile tinnitus and a holocephalic headache without well-defined migrainous features. Her history was otherwise unremarkable except for a 1-year history of lower back pain, which had progressed in intensity and now included intermittent radiation to posterior thighs. She denied any preceding illness, trauma, weight changes, weakness, bladder, or bowel symptoms. Bedside examination was noted for bilateral disc edema and a normal body mass index (BMI). The remainder of the examination including color vision, visual acuity, motility, and confrontational visual fields was unremarkable.

Section 2

The patient presented with a transient visual impairment which may localize throughout the afferent visual pathway including orbits, optic nerves, optic radiation, occipital lobes, and systemic or intracranial factors that may affect anywhere along this pathway. The differential for new, transient visual disturbances in a young adult can be broad and includes inflammatory/autoimmune (optic neuritis), infectious (neuroretinitis), structural (aneurysms and tumor), or other etiologies (migraines and idiopathic intracranial hypertension [IIH]). Although one might find it difficult to link the localization of the lower back pain to the visual symptoms, a single unifying lesion might provide a more logical explanation than 2 separate lesions.

Headache, visual impairment, and pulsatile tinnitus in this population may raise suspicion for IIH, formerly pseudotumor cerebri.^1,2 The differential at this time was broad, and secondary causes of intracranial hypertension must be excluded before IIH diagnosis. These conditions include intracranial mass lesion, obstruction of venous outflow (venous sinus thrombosis or compression), decreased CSF absorption (secondary to CNS infection or hemorrhage), increased CSF production (choroid plexus tumor), medication-induced, and endocrine or metabolic disorders (thyroid disease, Addison disease, etc).³

An MRI of the brain with gadolinium performed 4 months later showed mild prominence of the optic nerve subarachnoid space and bilateral intraocular protrusion of the optic nerve (Figure 1, A and B). There were no clear precipitating factors such as weight gain, medications, systemic illnesses, autoimmune, or hematologic conditions that may contribute to symptoms; however, overall history and examination were concerning for intracranial hypertension—warranting further diagnostic testing. The following month, a fluoroscopic-guided lumbar puncture was performed; however, it was unsuccessful after multiple attempts. Repeat neuro-ophthalmologic examination revealed worsening disc edema in both eyes, and initial Humphrey visual field testing showed enlarged blind spots in both eyes (Figure 2A).

Figure 2 Fundus Photographs Before and After Surgical Resection of Ependymoma

(A) Fundus photographs preoperatively showing optic nerve edema in both eyes, and the Humphrey visual field test showing enlarged blind spot in both eyes. (B) Fundus photographs 1 month postoperatively showing improved optic nerve edema in both eyes, and the Humphrey visual field test showing resolving blind spot enlargement in both eyes.

Section 3

Unguided lumbar punctures may be unsuccessful for a variety of reasons (e.g., medical hardware, scar tissue, mass lesions, degenerative spine disease, and body habitus). The rate of failure is approximately 19% for bedside procedures, most notably in patients with higher BMI and ultimately requiring fluoroscopic guidance.⁴ Guided lumbar punctures, as in our patient, are less likely to fail. Guided lumbar punctures may not be pursued or fail because of medical instability, patient compliance, body habitus, or pregnancy. Gadolinium-enhanced MRI lumbar-spine was undertaken after the unclear failed lumbar puncture and progressive lower back pain for evaluation of structural disease within the spine. MRI lumbar-spine showed a large intradural extramedullary mildly heterogenous T2 hyperintense mass filling the thecal sac from the level of L3-S2 with innumerable leptomeningeal/intradural enhancing foci (Figure 1, C and D).

The differential diagnosis for spinal cord lesions is extensive with main differentiation between neoplasm and mimics of neoplasm. Spinal cord lesions can be divided between extradural (outside the surrounding dural sac) and intradural (within the meninges), which are further divided into extramedullary (lesions outside the spinal cord) and intramedullary (lesions within the spinal cord). Extradural masses are typically tumor-based, most often metastases from prostate, breast, or lung.⁵ Several intradural-extramedullary, non-neoplastic lesions include arachnoid cyst, disc extrusion, infectious, and granulomatous disease.⁶ Several intradural-intramedullary, non-neoplastic lesions include vascular malformations (cavernous hemangioma and dural arteriovenous fistula), cord infarction, demyelinating disease (tumefactive MS), and infectious (abscess and tuberculosis). Intradural-extramedullary spinal tumors are most commonly schwannoma and meningioma, while intradural-intramedullary spinal tumors are typically ependymoma and astrocytoma.⁶ Ependymomas account for 60% of intradural-intramedullary tumors, of which 10%–15% are myxopapillary ependymoma (MPE), which was ultimately confirmed in our patient (Figure 1, C and D).

She was started on acetazolamide before undergoing neurosurgical resection of the tumor. Intraoperative CSF analysis noted a white blood cell count of 4/mm³, glucose of 77 mg/dL (serum 128 mg/dL), and protein of 184.1 mg/dL. Owing to the rarity of MPE, annual occurrence of 0.05–0.08 per 100,000 people, nonsurgical management (radiotherapy or chemotherapy) can vary; however, surgery remains the primary treatment with preference for gross total resection as in our patient.⁷ On neuro-ophthalmology follow-up 1 month postoperation, there was improvement in the disc edema (Figure 2B). She also reported improvement in her headaches and vision. One-year postoperatively, the patient reports no visual disturbances and her corrected visual acuity is 20/15 in both eyes.