Cervical spondylotic myelopathy: pathophysiology, clinical presentation, and treatment

Surgical management of 4-level cervical spondylotic myelopathy

The optimal surgical approach for 4-level cervical spondylotic myelopathy is controversial. The authors compared the clinical outcomes, radiographic changes, and complications of 53 patients who underwent either discontinuous corpectomy and fusion (DCF) with reservation of the middle vertebra (n=29) or laminectomy and fusion (n=24). Neurological function was measured using Nurick's grade and modified Japanese Orthopedic Association scores. The Neck Disability Index was recorded for neck-shoulder pain level evaluation. Patients' satisfaction with the surgery was evaluated using the Short Form 36. Segmental lordosis was measured. Both groups demonstrated significantly improved Nurick's grades and Japanese Orthopedic Association scores (P<.001), and the recovery rate was similar between the groups (59.86% ± 17.63% and 60.18% ± 12.01%, respectively). In terms of Neck Disability Index scores, Short Form 36 scores, and cervical lordosis measurements, no significant intergroup differences were found preoperatively. Mean postoperative Neck Disability Index scores were significantly lower in the DCF group (12.31 ± 1.91) than in the laminectomy group (15.04 ± 3.09; P=.000). Mean postoperative segmental lordosis was significantly higher in the DCF group (14.24 ± 2.29) than in the laminectomy group (9.96 ± 2.14; P=.001). The Short Form 36 scores significantly improved in both groups postoperatively (P<.01). Relative to the DCF group, the laminectomy group had a significantly longer operative time (192.25 ± 33.47 vs 192.25 ± 33.47 minutes, respectively; P<.01) and significantly more operative blood loss (455.41 ± 140.46 vs 253.79 ± 77.94 mL, respectively; P<.01). Discontinuous corpectomy and fusion with reservation of the middle vertebra is a safe and effective surgical treatment for 4-level cervical spondylotic myelopathy that results in significant functional improvement in most patients.

Improved diagnosis of spinal cord disorders with contact heat evoked potentials

Objective:

To evaluate the sensitivity of contact heat evoked potentials (CHEPs) compared with dermatomal somatosensory evoked potentials (dSSEPs) and clinical sensory testing in myelopathic spinal cord disorders (SCDs).

Methods:

In a prospective cohort study, light-touch (LT) and pinprick (PP) testing was complemented by dermatomal CHEPs and dSSEPs in patients with a confirmed SCD as defined by MRI. Patients with different etiologies (i.e., traumatic and nontraumatic) and varying degrees of spinal cord damage (i.e., completeness) were included. SCD was distinguished into 3 categories according to MRI pattern and neurologic examination: a) complete, b) incomplete-diffuse, and c) central or anterior cord damage.

Results:

Seventy-five patients were included (complete n = 7, incomplete-diffuse n = 33, central/anterior n = 35). In total, 319 dermatomes were tested with combined CHEPs and dSSEPs. CHEPs, dSSEPs, and clinical sensory testing were comparably sensitive to detect the myelopathy in complete (CHEPs 100%, dSSEPs 91%, PP and LT 82%) and incomplete-diffuse (CHEPs 92%, dSSEPs and PP 86%, LT 81%, p > 0.05 for all comparisons) cord damage. In central/anterior cord damage, CHEPs showed a significantly higher sensitivity than dSSEPs (89% compared with 24%, p < 0.001) and clinical sensory testing (PP 62%, LT 57%, p < 0.05). A subclinical sensory impairment was detected more frequently by CHEPs than dSSEPs (60% compared with 29%, p = 0.001).

Conclusions:

Assessment of spinothalamic pathways with CHEPs is reliable and revealed the highest sensitivity in all SCDs. Specifically in incomplete lesions that spare dorsal pathways, CHEPs are sensitive to complement the clinical diagnosis.