Operative findings and outcome of microvascular decompression/adhesiolysis for trigeminal neuralgia in multiple sclerosis without demyelinating brain stem lesions

•MVD/adhesiolysis is an effective treatment option for patients with MS-related TN without demyelinating brain stem lesions.•Increased arachnoid membranes/arachnoiditis at the trigeminal nerve entry zone can be the cause of the MS-related TN.•Patient who experience recurrence may benefit from repeat microvascular decompression/adhesiolysis. Trigeminal neuralgia (TN) in multiple sclerosis (MS) poses several challenges for treatment. Although these patients often have typical attacks, they may not be considered as candidates for microvascular decompression (MVD). Here we report on surgical findings and long term follow-up of MVD/ adhesiolysis in a series of patients with multiple sclerosis but without demyelinating brain stem lesions. Fifteen patients with MS-related TN underwent MVD/ adhesiolysis. Demyelinating brain stem lesions were excluded radiologically. Outcome of the intervention was assessed according to the Barrow Neurological Institute (BNI) pain intensity score at 3, 12, 24 months follow-up and at the last available follow-up (mean 88.2 months, range 38–146). All 15 patients benefited from MVD/adhesiolysis and were pain free on the first day of surgery. Intraoperative findings included arterial contact in 7/15 (47 %) patients, venous contact in 9/15 (60 %), and prominent arachnoid thickening in 12/15 (80 %). The distribution of the BNI pain intensity scores showed marked improvement at all follow-up evaluations. Five patients underwent repeat MVD/adhesiolysis for pain recurrence at a mean of 43 months after the first surgery. Long term evaluation at the last available follow-up demonstrated favorable outcome in 13/15 patients (BNI I-IIIa) (87 %), while 2/15 patients had limited benefit (BNI IV). MS-related TN in patients without demyelinating brain stem lesions may be related either to vascular conflicts or to focal arachnoiditis at the trigeminal nerve entry zone. MVD/ adhesiolysis may be considered as a useful treatment option in this subgroup of patients with regard to long term outcome.