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Study design: A prospective clinical cohort study. Objectives: To test if maximum voluntary ventilation (MVV), which is currently underutilized in diseases, serves for assessing subclinical ventilatory impairment in cervical spondylotic myelopathy (CSM). Setting: Kochi Medical School, Japan. Methods: We studied ventilatory function in 49 CSM patients and 20 age-and sex-matched control patients with either lumbar stenosis or lower limb osteoarthritis. All patients underwent ventilatory function studies consisting of flow volume curves, vital capacity (VC) and the MVV in 12 s before and after surgery. Tetraparesis was assessed by the functional scale of the Japanese Orthopaedic Association (JOA). Results: The CSM group had significantly smaller %forced VC , %peak expiratory flow rate (%PEFR) and %MVV than the control group preoperatively. In contrast to the control group, the CSM group showed a significant increase in %MVV from 74.9±18.7% preoperatively to 80.3 ± 19.0% postoperatively (Po0.005), but not in any other ventilatory measures. This postoperative increase in %MVV significantly correlated with the JOA score (r¼0.493; Po0.001). As a possible effect of diaphragmatic recovery, the %PEFR significantly increased postoperatively only in patients with the primary site of involvement at or rostral to C3-4. Conclusion: Of the various ventilatory measurements, MVV was most sensitive to changes in tetraparesis in CSM, presumably because MVV, unlike the other ventilatory measures, reflects the coordination in addition to the strength of respiratory muscles.

Study design: A case-control investigation. Objectives: The objective of this study was to quantitatively study impaired ability to appropriately adjust pinch strength while holding a small object in patients with cervical spondylotic myelopathy (CSM). Setting: Kochi Medical School Hospital, Japan. Methods: The subjects consisted of 19 CSM patients who had frequent episodes of failing to grasp and hold small objects in their daily life (Group A), 13 CSM patients who did not experience such episodes (Group B) and 16 healthy subjects (Control Group). We continuously measured the dynamic internal pressure of a pneumatic rubber object called a blower pinched by the subject, following two different sets of instructions: (1) pinching with eyes open and with the minimal strength required to prevent dropping; and (2) maintaining a constant pinch strength at given levels with eyes closed. Results: Compared with the other two groups, Group A subjects used a significantly (Po0.01) greater pinch strength to avoid dropping the blower held with eyes open and showed a significantly (Po0.01) greater deviation in pinch strength from the baseline values with eyes closed. These tendencies in Group A showed a significant correlation with the tactile perception threshold of the digits (Po0.01) but not with impairment of rapid repetitive movements of the digits that reflects spasticity. Conclusion: Our technique applied to CSM patients helps assess functional integrity primarily, if not exclusively, of the fasciculus cuneatus mediating the feedback signals from proprioceptive and cutaneous receptors in the digits, which are otherwise difficult to evaluate quantitatively.

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