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P T Procopio

Publications and source records attributed to P T Procopio.

4 recordsLinked to original sources
PubMed1982

Evoked potential changes produced by positioning for retromastoid craniectomy.

Reversible changes in brain stem auditory evoked potentials (BAEPs) occurred in a patient with hemifacial spasm when she was positioned for retromastoid craniectomy. The peak latencies increased and the amplitudes decreased. These alterations persisted for 3 hours, but returned immediately toward normal when the head was removed from pin fixation and the neck was returned to a neutral position. Similar BAEP changes were documented during a second procedure. Audiograms were normal pre- and postoperatively, although minimal BAEP changes were seen after operation. Our observation sheds light on possible mechanisms of intraoperative BAEP alteration and provides new information about the degree and duration of intraoperative BAEP distortion that can be tolerated in at least some cases without permanent neurological sequelae.

Brain Stem↗
PubMed1982

Intraoperative monitoring of brain-stem auditory evoked potentials.

Brain-stem auditory evoked potentials (BAEP) were monitored during 545 neurosurgical operations in the cerebellopontine angle. The BAEP were irreversibly obliterated in five patients who required deliberate section of the auditory nerve. Technical difficulties interfered with monitoring in three cases, and three patients had deafness and absent BAEP preoperatively. Reversible alterations in BAEP were seen during 32 operations, with recovery after as long as 177 minutes of virtually complete obliteration. Changes in BAEP were associated with surgical retraction, operative manipulation, positioning of the head and neck for retromastoid craniectomy, and the combination of hypocarbia and moderate hypotension. In 19 cases, waveforms improved after specific interventions made by the surgeon or anesthesiologist because of deteriorating BAEP. In 13 other cases, BAEP recovered after maneuvers not specifically related to the electrophysiological monitoring, most often completion of operative manipulation. Whenever BAEP returned toward normal by the end of anesthesia, even after transient obliteration, hearing was preserved. Irreversible loss of BAEP occurred only when the auditory nerve was deliberately sacrificed. The authors conclude that monitoring of BAEP may help prevent injury to the auditory nerve and brain stem during operations in the cerebellopontine angle.

Adult↗