Microvascular decompression for hyperactive cranial nerve rhizopathies

Abstract

Hyperactive dysfunction syndromes including trigeminal neuralgia, hemifacial spasm and glossopharyngeal neuralgia, may result from vascular loops distorting the intracranial portion of the affected nerves. Microvascular decompression has been recommended as treatment for these conditions. Posterior fossa exploration in 16 patients who presented with hyperactive cranial rhizopathies revealed vascular distortion of the relevant cranial nerve in 14 patients. Amongst patients with trigeminal neuralgia and superior cerebellar artery (SCA) was responsible in 4 cases, the anterior inferior cerebellar artery (AICA) in 2, an ectatic basilar artery in 2 and a vein was the cause in one patient with atypical facial pain. In two patients with combined trigeminal and glossopharyngeal neuralgia the posterior inferior cerebellar artery (PICA) was responsible for the glossopharyngeal pain and the SCA for the trigeminal neuralgia. One patient with classical glossopharyngeal neuralgia had a loop of PICA distorting the nerve. The facial nerve was indented by a loop of AICA in two patients with hemifacial spasm. Insertion of a muscle graft between the appropriate nerve and vessel gave relief in 14 patients which has been maintained at follow-up (l-20 months; mean 10 months). In patients experiencing glossopharyngeal neuralgia and glossopharyngeal nerve and upper two vagal nerve filaments were divided in addition to mobilising the loop of PICA. One patient suffered a myocardial infarction and died later. Post operative complications included severe headache (4 patients), confusion (2) and a superficial wound infection (1). Two patients required re-exploration for cerebrospinal fluid fistulae. Two patients complained of transient hyperaesthesiae related to the incision scar. One patient suffered sensorineural deafness which had only slightly improved at review. Trigeminal pain returned in two patients who had no evidence of neuro-vascular compression but re-exploration revealed an arterial loop (of AICA) which had been missed previously; mobilisation of this relieved the pain.