IONM is use to monitoring nervous tissues (including brain, spinal cord, cranial nerves and peripheral nerves) in real-time during surgeries, alert neurological injuries and corrective measures and prevent disability. There are various IONM monitoring techniques including evoke potentials (SSEP, BAEP, MEP), EMG (Free-running and triggered), NAP (Nerve action potential) and Electroencephalography (EEG) to monitor the functional integrity of neural structures. SSEP evaluates integrity of posterior column-medial lemniscus pathway. SSEP is clinical use in spinal cord surgeries, vascular surgeries (carotid endarterectomy, cerebral aneurysm surgery etc), and localization of sensor motor cortex. BAEP evaluates integrity of peripheral and central auditory pathway. BAEP is clinical use in CP angle tumors surgery (acoustic neuroma ,meningioma), microvascular decompression of CN-VII for hemifacial spasm, CN-V for trigeminal neuralgia, CN-IX for glossopharyngeal neuralgia, skull base surgery, Suboccipital decompression (e.g. fractures/dislocation C-1vertebra, chiari malformation). MEP evaluates integrity of motor pathway. MEP is sensitive to neuromuscular blocker anesthetic medications. Clinical utility of MEP including any surgery risking motor pathway injury include tumor near the motor cortex or corticospinal tract, intracranial aneurysm clipping, posterior fossa surgery, tethered cord or cauda equina surgeries, spinal deformity or fracture surgery, vertebral tumor resections, and anterior cervical discectomy, descending aortic procedures, spinal arteriovenous malformation interventions and carotid endarterectomy. EMG (free running and triggered) evaluates integrity of innervating nerves and electrical activity of muscles. Clinical utility of facial and other cranial nerve monitoring in posterior fossa surgery (eg, acoustic neuroma), selective dorsal rhizotomy, tethered cord release , Pedicle screw placement and Anal or urinary sphincter function monitoring.
Ali, Liaquat; Iqrar, Ambreen; and Asumal Khealani, Bhojo
"Review of various intraoperative neurophysiologic monitoring techniques,"
Pakistan Journal of Neurological Sciences (PJNS): Vol. 11
, Article 10.
Available at: http://ecommons.aku.edu/pjns/vol11/iss2/10