6th Edition of Neurology World Conference 2026

Abstract

Eight-and-a-half syndrome is a rare neurological presentation that consists of the concurrent manifestation of three nerve palsies/disorders: ipsilateral lower motor neuron type facial palsy, conjugate horizontal gaze palsy, and ipsilateral internuclear ophthalmoplegia (INO). The lesion typically localizes to the ipsilateral paramedian pontine reticular formation (PPRF), median longitudinal fasciculus (MLF), and the ipsilateral facial nerve fascicle. The most common causes for eight-and-a-half syndrome are acute ischemic stroke of the brainstem or demyelinating disease. This report showcases a patient who presented with eight-and-a-half syndrome due to multifocal space-occupying lesions of the brain, particularly primary central nervous system lymphoma(PCNSL), an uncommon cause of this presentation. Case Presentation A 32-year-old female with HIV, not on antiretroviral therapy, presented to the ED as a stroke alert for sudden left-sided facial weakness, slurred speech, mild ataxia of the left upper extremity, and right gaze deviation of one day. The patient was recently discharged on clindamycin, primaquine, fluconazole, steroid taper, and HIV medications for acute respiratory failure with presumed PJP a week prior. Ophthalmology was consulted for right gaze preference, nystagmus OU, and HIV retinopathy. The right eye was fixed to the right, with intermittent nystagmus on leftward gaze and no adduction appreciated. The left eye was able to adduct and look right, but was unable to abduct across the midline. MRI findings revealed multifocal ring-enhancing CNS lesions, including one located in the right pons causing effacement of the fourth ventricle. The patient underwent endotracheal intubation for respiratory support after a suspected aspiration event and chest x-ray suggesting pneumonia. Infectious disease was consulted and initiated broad-spectrum empiric therapy with Zosyn and Vancomycin. After experiencing acute respiratory failure, the patient was transferred to the ICU for intensive monitoring. CSF PCR for Epstein-Barr virus (EBV) was positive, suggesting the etiology of the patient’s symptomatology was primary CNS lymphoma. Neurosurgery did not endorse biopsy due to the patient’s high-risk status and the procedure’s invasiveness. Along with the patient’s progressively declining neurological examinations, the patient ultimately transitioned to Comfort Care and was terminally extubated. Discussion Untreated HIV can progress into neurological emergencies primarily due to the development of CNS-related lesions like CNS lymphoma, toxoplasmosis, or progressive multifocal leukoencephalopathy(PML). This patient’s severe immunosuppression (CD4 of 48 cells/ mm³) without antiretroviral therapy allowed EBV-infected B cells to undergo substantial lymphomagenesis. Involvement of the dorsal tegmentum of the caudal pons, particularly the MLF, PPRF, and facial nerve fascicle, is uncommon in PCNSL. PCNSL typically has a predilection for supratentorial structures, including the basal ganglia and periventricular white matter. The timely management and treatment of HIV with antiretroviral therapy is essential to yield optimal clinical outcomes and preclude long-term sequelae such as movement disorders, ocular palsies, eight-and-a-half syndrome, and respiratory/autonomic dysfunction.