Spinal adhesive arachnoiditis as a disabling and underdiagnosed complication of cerebral subarachnoid neurocysticercosis: a case series

Spinal adhesive arachnoiditis (SAA) is a severe and potentially disabling complication of neurocysticercosis (NCC), but it remains poorly characterised. We conducted a retrospective descriptive case series including patients evaluated between 2000 and 2025 at a tertiary care hospital in Mexico City. Inclusion criteria includeda definitive NCC diagnosis, SAAconfirmedby magnetic resonance imaging(MRI), complete clinical and radiological data, and a minimum follow-up of 12 months. Eight patients were included. All presented the basal subarachnoid form of NCC with parasites located in the pontobulbar cisterns. At NCC diagnosis, all patients had intracranial hypertension and markedly abnormal cerebrospinal fluid. SAA was diagnosed concomitantly with NCC in three patients, while in the remaining five,diagnosis was established between 12 and 108 months later. At SAA diagnosis, all patients presented lumbar pain, motor deficits were observed in five, and sensory deficits in six. MRI confirmed lumbosacral SAA in all patients. Despite antiparasitic and symptomatic treatment, functional outcomes were generally poor: mean Karnofsky Performance Scale score decreased from 81.25 at SAA diagnosis to 71.25 after a mean follow-up of 128 months, with four patients showing progressive functional decline. In conclusion, SAA is a rare but disabling and likely underdiagnosed complication of extraparenchymal-NCC, characterised by delayed onset, persistent inflammation, and progressive functional decline despite treatment. The large volume of the lumbar intradural subarachnoid space may explain the frequent asymptomatic period preceding SAA diagnosis. Early recognition through systematic spinal MRI in patients with pontobulbar cistern NCC may represent a critical window for intervention.