SUMMARY

Regardless of the type of intraoperative neurologic monitor, several principles must be followed for the use of neurologic monitoring to provide potential benefit to the patient. First, the pathway at risk during the surgical procedure must be amenable to monitoring. Second, if

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We have reviewed the most common clinically used intraoperative neurologic monitors. Ideally, clinical studies can provide outcome data on the efficacy of a neurologic monitor in a given procedure to improve neurologic outcome. Unfortunately, although there is a wealth of clinical experience with many of these monitoring modalities,

TABLE 38-11 -- Current practice in neurologic monitoring

Procedure	Monitors	Current Practice
Carotid endarterectomy	Neurologic examination of awake patient	Most available literature supports use of at least one of EEG, SSEP, TCD, awake patient
	EEG
	SSEP
	TCD
	CO	Limited data available; inadequate normative population data
Scoliosis surgery	SSEP	Monitoring recommended and may substitute for wake-up testing
	Wake-up test	Largely abandoned in centers using electrophysiologic monitoring. Monitoring is not continuous, and false-negative monitoring patterns have been reported
	MEP	Increased clinical use since transcranial electrical stimulation was FDA approved; overall utility to be determined but probably useful
Acoustic neuroma	Facial nerve monitor	Facial nerve monitoring recommended
	BAEP	Shows some clinical evidence of improved outcome in some procedures
Intracranial aneurysm clipping	SSEP	Used routinely in some centers; limited clinical data on outcome but appears clinically useful during anterior circulation procedures
	EEG
Cranial nerve V decompression	BAEP	Used in some centers; reduces hearing loss
Cranial nerve VII decompression	BAEP	Data from small series show improved hearing preservation
Supratentorial mass lesions	SSEP	Used in some centers in selected high-risk procedures
Infratentorial mass lesions	BAEP or SSEP	BAEP to detect retractor-related VIII nerve injury; SSEP for rare, high-risk lesions adjacent to ascending sensory pathways
Decompression of spinal stenosis	SSEP	Used in some centers in high-risk procedures (more often cervical)
Spinal cord trauma	SSEP	Used in some centers in high-risk procedures
Cardiopulmonary bypass	EEG	Used routinely in some centers; actively studied but no outcome data yet
	TCD
	SjvO2
	CO
Aortic coarctation	SSEP	Used routinely in a few centers; no widespread acceptance
Aortic aneurysm repair	SSEP	Used routinely in a few centers; no widespread acceptance
	MEP	Used routinely in a few centers; no widespread acceptance
BAEP, brainstem auditory evoked potential; CO, cerebral oximetry; EEG, electroencephalogram; FDA, U.S. Food and Drug Administration; MEP, motor evoked potential; NIH, National Institutes of Health; SjvO2 , jugular bulb venous oxygen saturation; SSEP, somatosensory evoked potential; TCD, transcranial Doppler ultrasound.

there is little in the way of randomized, prospective studies evaluating the efficacy of neurologic monitoring. Based on clinical experience with neurologic monitoring and on nonrandomized clinical studies in which neurologic monitoring is used and typically compared with historical controls, practice patterns for use of neurologic monitoring have developed. For certain procedures, neurologic monitoring is recommended and used by most centers. For other procedures, monitoring is used almost routinely in some centers but not in others, and for some procedures, there is no clear clinical experience or evidence indicating that monitoring is useful at all (e.g., experimental use). For some procedures, monitoring is used selectively for patients believed to be at higher risk for intraoperative neurologic injury. Table 38-11 provides a summary of current clinical practice.