Intraoperative monitoring: do you know where your neurophysiologist is?

OBJECTIVE: The professional practice of intraoperative monitoring has evolved over the past 30 years. This report describes the field's current state and how site of service affects practice. METHODS: A survey queried American Academy of Neurology intraoperative monitoringneurologist members about their intraoperative monitoring volume, case type, duration, numbers of simultaneous cases, and location of the monitoring physician. RESULTS: Physicians located locally typically monitored fewer cases annually and simultaneously compared with physicians who monitored from remote locations. Physicians at remote locations monitored proportionally more spine procedures, whereas physicians who monitored locally monitored more intracranial procedures and a greater variety of cases. CONCLUSIONS: The remote monitoring practice model is different from local models in annual volume, simultaneous cases, work per case, and types of cases.

Transcranial magnetic stimulation--may be useful as a preoperative screen of motor tract function.

UNLABELLED: Transcranial motor stimulation with noninvasive cortical surface stimulation, using a high-intensity magnetic field referred to as transcranial magnetic stimulation generally, is considered a nonpainful technique. In contrast, transcranial electric stimulation of the motor tracts typically cannot be done in unanesthesized patients. Intraoperative monitoring of motor tract function with transcranial electric stimulation is considered a standard practice in many institutions for patients during surgical procedures in which there is potential risk of motor tract impairment so that the risk of paraplegia or paraparesis can be reduced. Because transcranial electric stimulation cannot be typically done in the outpatient setting, transcranial magnetic stimulation may be able to provide a well-tolerated method for evaluation of the corticospinal motor tracts before surgery. METHODS: One hundred fifty-five patients aged 5 to 20 years were evaluated preoperatively with single-stimulation nonrepetitive transcranial magnetic stimulation for preoperative assessment. RESULTS AND CONCLUSIONS: The presence of responses to transcranial magnetic stimulation reliably predicted the presence of responses to transcranial electric stimulation intraoperatively. No complications occurred during the testing, and findings were correlated to the clinical history and used in the setup of the surgical monitoring.

Neurophysiologic intraoperative monitoring in pediatrics.

Neurophysiologic intraoperative monitoring, using somatosensory, brainstem auditory, and visual evoked potentials, transcranial electric motor stimulation, and electromyography, is typically used during complex surgeries involving the motor and sensory cortex, brainstem, cranial nerves, spinal cord, nerve root, peripheral roots, brachial plexus, lumbar plexus, and peripheral nerves. The particular type of surgery and the neurologic structures at risk determine the type of monitoring chosen. Although many methods are the same in adult and pediatric patients, some differences in the pediatric population will be discussed here. In general, monitoring consists of two types. The first involves monitoring data which is obtained on an ongoing basis, with comparisons to data obtained at the outset of surgery (baseline). The second form of monitoring involves mapping neural structures, so that a neural structure in the field is identified accurately, to avoid injuring it, or to demonstrate its degree of neurophysiologic function or impairment. In this paper we discuss both forms of monitoring and their general applications, including unique features or modifications needed in the pediatric population.