Acute unilateral sixth cranial nerve palsy and headache as initial manifestations of carcinomatous meningitis.

Carcinomatous meningitis refers to the spread of cancer cells to the leptomeninges and subarachnoid spaces. It is most frequently associated with lung, breast, and melanoma cancers. The onset can be subtle or present with an isolated symptom, even with acute onset. We report a case of cerebral carcinomatous meningitis presenting with isolated left sixth cranial nerve palsy and persistent headache. Case Report: A 62-year-old man with a history of urothelial carcinoma, previously treated with right nephroureterectomy and adjuvant chemo- therapy, presented to the emergency department with double vision due to left sixth cranial nerve palsy that had developed within the past 24 hours, and a severe posterior neck headache that had been resistant to anti-inflammatory therapy for approximately 40 days. Chest and abdomen CT scans from the previous two weeks showed no signs of recurrent neoplastic disease. Neurological evaluation revealed a total deficit in the abduction of the left eye and posterior neck headache, without other signs of meningismus. Suspecting idiopathic intracranial hypertension, a brain MRI was performed, which showed no abnormalities on T1 and T2-weighted sequences, and an eye examination revealed no papilledema. The patient was transferred to our department and underwent a diagnostic lumbar puncture, which showed normal opening pressure, elevated protein levels, low glucose levels, and 80 cells in the cerebrospinal fluid (CSF). In the following days, the patient experienced neurological deterioration with signs of meningismus, hyponatremia, worsening headache, and decreased alertness. Micro- biological tests on blood and CSF were negative, while a subsequent eye examination revealed papilledema in the left eye. A follow-up brain MRI showed enhancement of the parieto-occipital and peri-cerebellar cortical sulci in the post-contrast FLAIR sequence. Finally, cytological examination confirmed the neoplastic nature of the cells in the CSF. Conclusions: Cerebral carcinomatous meningitis should be considered a possible diagnosis in patients with isolated cranial nerve involvement, even with acute onset, and a history of carcinoma, even if follow-up tests suggest they are free of neoplastic disease. The most suitable neuroimaging study is brain MRI with T1-weighted and FLAIR sequences at least 10 minutes after contrast injection. CSF analysis typically shows increased opening pressure, elevated protein levels, and low glucose levels. The diagnosis is confirmed by the presence of tumor cells in the CSF.