Hearing prognosis and intraoperative guidance of brainstem auditory evoked potential in microvascular decompression.

Intraoperative monitoring of brainstem auditory evoked potential (BAEP) was done in 34 patients submitted to microvascular decompression (MVD). Seventeen of these patients had trigeminal neuralgia, and 17 had hemifacial spasm. Transitory postoperative hearing loss was observed in 6 (18%) of the patients, and permanent hearing loss was observed in 2 (6%) of the patients. Wave I-V interpeak latency (IPL) was calculated during each step of the MVD procedure in order to identify the dangerous steps of the surgery. Wave I-V IPL abnormalities occurred more frequently during cerebellar retraction. Of the 6 patients who had total loss of BAEP lasting throughout the surgery, 1 (17%) had definitive deafness. Ten of the 34 patients had an absence or partial diminution of BAEP without total normalization before the end of surgery. Among these 10 patients, 2 had transitory hearing loss and 1 had permanent hearing loss.

[Peroperative monitoring of early auditory evoked potentials in microsurgical vascular decompression for trigeminal neuralgia or hemifacial spasm]. / Apport du monitorage per-opératoire des potentiels évoqués auditifs précoces dans la décompression vasculaire microchirurgicale pour névralgie du trijumeau ou spasme hémifacial.

Intra-operative B.A.E.P. monitoring have been performed in two series of patients who underwent Microsurgical Vascular Decompression (M.V.D.) of the Vth and VIIth cranial nerves in the posterior fossa. The first series consisted of 17 patients among the 400 operated on for Trigeminal Neuralgia (T.N.), the second one also of 17 patients among the 25 treated for Hemifacial spasm (H.S.), over the last four years. The equal number of recorded patients in the two groups is totally fortuitous. The aim of the work was to correlate the electrophysiological changes: 1) to the surgical manoeuvres potentially responsible for B.A.E.P. alterations, in order to modify the M.V.D. technique, so as to minimize the risks of hearing loss, 2) to the eventual post-operative auditory disturbances, in order to define prognostic criteria from B.A.E.P. monitoring. I. Intra-operative B.A.E.P. modifications were graded into 4 categories, according to their degree of severity (table II): minimal changes (category 1), increase in latency returning to normal (2) or without normalization (2a) before end of surgery, abolition or partial decrease of responses returning to normal (3) or without complete normalization (3a) before end of surgery, total B.A.E.P. loss lasting through the entire procedure (4). Patients operated on for H.S. had more often significant B.A.E.P. changes than those with T.N., respectively 10 and 6 for categories 3a and 4 together. Auditory function was at risk mainly during cerebellar retraction (especially if cerebello-pontine angle was approached laterally) and during vascular manipulation of the labyrinthine artery (which can generat vasospasm).(ABSTRACT TRUNCATED AT 250 WORDS)

[Idiopathic giant cell granulomas of the pituitary gland. Apropos of 2 cases]. / Les granulomes idiopathiques à cellules géantes de l'hypophyse. A propos de 2 cas.

Two cases are reported of two women who had developed progressive hypopituitarism without visual disturbances. Pituitary tumors were evoked by radiological findings. The patients underwent surgical removal of invasive intrasellar tumor by transphenoidal route. Giant-cell granuloma was histologically demonstrated with negative special staining for tuberculosis acid-fast bacilli, bacteria and fungi. Secondary granuloma due to tuberculosis, brucellosis or neurosarcoidosis was ruled out by serological grounds. The prognosis was discusses through a follow-up of 7 years in the first case and 7 months in the second one. The appropriately documented 31 cases collected from the literature were compared with our two cases.

[Intraoperative brainstem auditory evoked potential in the microvascular decompression of the 5th and 7th cranial nerves]. / Potentiels évoqués auditifs précoces per-opératoires dans les décompressions neurovasculaires des nerfs trijumeau et facial.

Microvascular decompression techniques are rational surgical procedures for treating trigeminal neuralgia and facial hemispasm, with results ranging from good to excellent in 90% of cases. Among the most frequent complications recorded in the literature concerning these decompressions, impairment of the facial nerve and auditory nerve account for 5% to 10% due to mechanical traction and/or vascular injury. The peroperative use of early brain-stem evoked potentials (BAEP) was performed on 17 patients in a series of 325 decompressions of the trigeminal nerve, and on 17 patients in a series of 25 decompressions for facial hemispasm. Such peroperative monitoring is considered to be most important in the surgical technique. The author reports on his experience and results.