Case Presentation: A 54 year-old African American female with a past medical history of hypertension and sickle cell anemia presented with acute onset of headache, blurry vision and confusion with multiple falls over ten days. On presentation, her vitals were within normal limits. She was lethargic and only able to answer simple questions. Physical examination revealed diplopia and lateral deviation of the left eye. She also had left-sided conductive hearing loss and left-sided lower extremity strength was 4/5. There were no other focal neurologic deficits or other apparent signs of meningitis. Computed Tomography (CT) of the brain without contrast and CT angiogram were unremarkable. A lumbar puncture was done which revealed an opening pressure of 32 cm H2O. The cerebrospinal fluid (CSF) antigen and titers were positive for cryptococcus. and Subsequent testing for human deficiency virus was positive. In retrospect, patient was found to have untreated HIV since 2006 which she did not disclose to providers. The patient was started on flucytosine and amphotericin B. She underwent serial lumbar punctures to monitor for improvement. Her CSF opening pressure, cryptococcal antibody titers and all symptoms including left abducens nerve palsy improved. The patient was then transitioned to oral fluconazole and started on antiretroviral therapy with bictegravir, emtricitabine, and tenofovir alafenamide prior to being discharged.
Discussion: Sixth cranial nerve palsy is commonly caused by mass lesions, multiple sclerosis, and trauma. It can also be a result of infection such as cryptococcal meningitis as was the case with our patient. In our review of the literature, isolated abducens nerve palsy can be a presenting sign for complications of advanced HIV infection like cryptococcal meningitis or lymphoma 1-6. The mechanism by which the abducens nerve palsy occurs is either by elevated intracranial pressure or by direct invasion of the abducens nerve,8. It is imperative that a patient who presents with an acute sixth cranial nerve palsy be evaluated via lumbar puncture for intracranial hypertension and possible infectious causes like HIV.
Conclusions: In the case of isolated sixth cranial nerve palsy, infectious workup should include evaluation for cryptococcal meningitis especially in patients with suspected immunocompromised states like HIV.