• Kazuhiro Fujimoto, Tsukasa Kanchiku, Yasuaki Imajo, Hidenori Suzuki, Masahiro Funaba, Norihiro Nishida, and Toshihiko Taguchi.
• Department of Orthopaedic Surgery, Yamaguchi University Graduate School of Medicine, Ube, Yamaguchi, Japan.
• Spine. 2017 Jun 15; 42 (12): 895-902.

Study DesignA retrospective study.ObjectiveThis study investigated the pathophysiology of compressive cervical myelopathy (CCM) with prolonged central motor conduction time (CMCT) in the upper limbs (ULs) rather than lower limbs (LLs) and prolonged CMCT at the thoracic level (TL).Summary Of Background DataEarlier reports indicated the usefulness of CMCT to assess preoperative CCM severity. However, little information exists on patients with prolonged CMCT-UL rather than CMCT-LL and prolonged CMCT-TL.MethodsNinety-four patients (61 men, 33 women; age 28-87 years) with CCM who underwent cervical laminoplasty participated. Fifty-three volunteers provided normal data on CMCT-UL and LL. CMCT-TL was calculated as CMCT-LL - CMCT-UL. We defined three groups: group U, prolonged CMCT-UL rather than CMCT-LL (n = 14); group E, prolonged CMCT-UL and CMCT-LL equality (n = 43); and group L, prolonged CMCT-TL (n = 37). We evaluated intraoperative recording of spinal cord evoked potentials (SCEPs), neurological findings, and surgical outcomes.ResultsControl mean CMCT-UL was 5.2 ± 0.7 ms, CMCT-LL was 11.8 ± 1.1 ms, and CMCT-TL was 6.6 ± 1.2 ms. SCEPs results were significantly different between CCM patients in group U and L (P < 0.01). Almost all patients in three groups showed hyperreflexia of the patellar tendon reflex, but great toe position sense was abnormal in most patients in group L only. Japanese Orthopedics Association (JOA) scores improved postoperatively in all patients. There was a significant difference in recovery rate of the JOA score between group L and other groups (both P < 0.05).ConclusionMultimodal SCEPs, clinical findings, and surgical outcomes showed that patients with CCM and prolonged CMCT-TL had substantial disorders of the gray matter, lateral corticospinal tract, and posterior funiculus. Spine surgeons should be aware that prognosis may be poor even after surgery in patients with severe myelopathy such as prolonged CMCT-TL.Level Of Evidence4.

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