Superior sensitivity of motor over somatosensory evoked potentials in the diagnosis of cervical spondylotic myelopathy

Abstract

Myelopathy secondary to cervical spondylosis is often a difficult clinical diagnosis. Furthermore, with the introduction of magnetic resonance imaging (MRI) an increasing number of patients are identified with spondylotic cervical spinal cord compression. We analyzed the value of functional assessment of the spinal cord by motor and sensory evoked potentials (MEP and SEP) in the detection of myelopathy, with special emphasis on the correlation of clinical and electrophysiological findings. Fifty-one patients with at least some degree of spinal cord compression because of cervical spondylosis, as shown by MRI, were included in the study, grouped according to clinical symptoms. We found that patients who had no clinical symptoms whatsoever indicating myelopathy (they were referred to MRI examination mostly because of cervical radiculopathy), had in the large majority normal MEP and SEP findings. Patients with slight, unspecific and non-confirmative symptoms without pyramidal signs had mostly abnormal MEP but normal SEP findings. This points to the superior sensitivity of MEP over SEP in detecting myelopathy in its early stages. Patients with obvious clinical signs of myelopathy, including pyramidal signs had both abnormal MEP and SEP findings. Altogether these findings may help clinicians in interpreting MRI signs of cervical spinal cord compression.

Correlation of force control with regional spinal DTI in patients with cervical spondylosis without signs of spinal cord injury on conventional MRI

“…This is coherent with human postmortem findings in showing white matter changes occurring mainly in the lateral CST [29]. It is also consistent with abnormal motor, but normal sensory-evoked potentials in cervical spondylosis with neurological symptoms [30]. Similarly, a recent animal model of cervical myelopathy showed early occurring corticospinal degeneration and compromised spinal cord microvasculature [27].…”

How has electrophysiology changed the management of cervical spondylotic myelopathy?

“…Another disadvantage is that SSEPs are not sufficiently precise to localize the level of cord involvement [4]. Moreover, MEP elicited by transcranial magnetic stimulation (TMS) were shown to be of higher sensitivity than SSEPs for the detection of CSM particularly in the early stages [5], although the latter technique provided complementary diagnostic value in this respect [6]. These have to be weighed against several potential advantages, such as its relative simplicity, safety and low cost.…”

High-frequency Stimulation Restored Motor-evoked Potentials to the Baseline Level in the Upper Extremities but Not in the Lower Extremities Under Sevoflurane Anesthesia in Spine Surgery

“…[1][2][3][4] However, MEPs are not widely utilized in the operating room because they are considerably affected by general anesthesia, especially with volatile anesthetics, including halothane, enflurane, isoflurane, sevoflurane, and desflurane. [1][2][3][4] However, MEPs are not widely utilized in the operating room because they are considerably affected by general anesthesia, especially with volatile anesthetics, including halothane, enflurane, isoflurane, sevoflurane, and desflurane.…”