How has electrophysiology changed the management of cervical spondylotic myelopathy?

Abstract

Cervical spondylosis occurs universally, with cervical spondylotic myelopathy (CSM) as its most serious consequence. The electrical property of the spinal cord and its susceptibility to injury renders electrophysiology relevant to the management of CSM, as addressed in this review. Somatosensory-evoked potentials evaluate spinal cord integrity with regards to posterior column functions exclusively. Although motor-evoked potentials may be more sensitive than the former and may be utilized intraoperatively, they are susceptible to interference by inhalational anaesthetics. Electromyography may play a role in minimizing C5 root damage and spinal cord-evoked potentials can localize spinal conduction block during CSM surgery. Critically reviewing the available evidence, electrophysiology cannot be universally recommended as mandatory in the management of CSM at present. It may, however, play emergent, isolated roles in the diagnosis, follow-up and treatment of this common disorder.

Transcranial magnetic motor evoked potentials in Great Danes with and without clinical signs of cervical spondylomyelopathy: Association with neurological findings and magnetic resonance imaging

“…Similar findings have been reported in human cervical spondylotic myelopathy (Tavy et al, 1994; Lo et al, 2004, 2007). One study reported absent TMMEPs in 34/141 (24.1%) people with cervical spondylotic myelopathy of varying severities (Lo et al, 2004).…”

“…In humans, TMMEPs have been used to evaluate the functionality of the motor pathways in cervical spondylotic myelopathy, which is a common cause of chronic compressive cervical myelopathy similar to canine cervical spondylomyelopathy (CSM) (Di Lazzaro et al, 1999; Lo, 2007; da Costa, 2010). Magnetic resonance imaging (MRI) is typically used to diagnose this human disease and define the compressive sites, but it cannot provide information about spinal cord (SC) functionality (Capone et al, 2013).…”

Cervical decompression and reconstruction without intraoperative neurophysiological monitoring

“…Additionally, the capacity of SSEPs to predict postoperative deficits is suboptimal because SSEPs do not monitor motor function, and they usually cannot specifically localize the level of abnormality. 12,18,28 Because of these constraints, Deletis and Sala 10 suggested that the exclusive use of SSEP monitoring is inappropriate, and their limitations must be understood. The lack of specificity of SSEP monitoring has prompted the use of MEP monitoring during cervical decompression.…”

Human motor evoked potential responses following spinal cord transection: an in vivo study

“…36 Furthermore, MEPs may be more sensitive to ischemia than SSEPs and less likely to deteriorate after midline myelotomy, unlike SSEPs. 4,5,7,10,12,24,[34][35][36]40 Also, as demonstrated in this case, not only will MEPs often be present in neurologically compromised patients, 9 but they may also be able to detect subclinical deficits, 3,23,38 whereas SSEPs are significantly more likely to be absent in the normal and compromised neurological states. In a recent prospective trial, 38.7% of patients undergoing a variety of spinal procedures had either significantly diminished or absent tibial SSEPs.…”