title: Subclinical respiratory dysfunction in chronic cervical cord compression: a pulmonary function test correlation.
abstract: OBJECTIVE Respiratory abnormalities are well documented in acute spinal cord injury; however, the literature available for respiratory dysfunction in chronic compressive myelopathy (CCM) is limited. Respiratory dysfunction in CCM is often subtle and subclinical. The authors studied the pattern of respiratory dysfunction in patients with chronic cord compression by using spirometry, and the clinical and surgical implications of this dysfunction. In this study they also attempted to address the postoperative respiratory function in these patients. METHODS A prospective study was done in 30 patients in whom cervical CCM due to either cervical spondylosis or ossification of the posterior longitudinal ligament (OPLL) was diagnosed. Thirty age-matched healthy volunteers were recruited as controls. None of the patients included in the study had any symptoms or signs of respiratory dysfunction. After clinical and radiological diagnosis, all patients underwent pulmonary function tests (PFTs) performed using a standardized Spirometry Kit Micro before and after surgery. The data were analyzed using Statistical Software SPSS version 13.0. Comparison between the 2 groups was done using the Student t-test. The Pearson correlation coefficient was used for PFT results and Nurick classification scores. A p value < 0.05 was considered significant. RESULTS Cervical spondylotic myelopathy (prolapsed intervertebral disc) was the predominant cause of compression (n = 21, 70%) followed by OPLL (n = 9, 30%). The average patient age was 45.06 years. Degenerative cervical spine disease has a relatively younger onset in the Indian population. The majority of the patients (n = 28, 93.3%) had compression at or above the C-5 level. Ten patients (33.3%) underwent an anterior approach and discectomy, 11 patients (36.7%) underwent decompressive laminectomy, and the remaining 9 underwent either corpectomy with fusion or laminoplasty. The mean preoperative forced vital capacity (FVC) (65%) of the patients was significantly lower than that of the controls (88%) (p < 0.001). The mean postoperative FVC (73.7%) in the patients showed significant improvement compared with the preoperative values (p = 0.003). The mean postoperative FVC was still significantly lower than the control value (p = 0.002). The mean preoperative forced expiratory volume in 1 second (FEV1) (72%) of the patients was significantly lower than that of the controls (96%) (p < 0.001). The mean postoperative FEV1 (75.3%) in the cases showed no significant improvement compared with the preoperative values (p = 0.212). The mean postoperative FEV1 was still significantly lower than the control value (p < 0.001). The mean postoperative FEV1/FVC was not significantly different from the control value (p = 0.204). The mean postoperative peak expiratory flow rate was significantly lower than the control value (p = 0.01). The mean postoperative maximal voluntary ventilation was still significantly lower than the control value (p < 0.001). On correlating the FVC and Nurick scores using the Pearson correlation coefficient, a negative correlation was found. CONCLUSIONS There is subclinical respiratory dysfunction and significant impairment of various lung capacities in patients with CCM. The FVC showed significant improvement postoperatively. Respiratory function needs to be evaluated and monitored to avoid potential respiratory complications.
authors.affiliation: Departments of 1 Neurosurgery and.
authors.forename: Indira Devi
authors.initials: ID
authors.lastname: Bhagavatula
authors.affiliation: Departments of 1 Neurosurgery and.
authors.forename: Dhananjaya I
authors.initials: DI
authors.lastname: Bhat
authors.affiliation: Department of Neurosurgery, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry;
authors.forename: Gopalakrishnan M
authors.initials: GM
authors.lastname: Sasidharan
authors.affiliation: Departments of 1 Neurosurgery and.
authors.forename: Rakesh Kumar
authors.initials: RK
authors.lastname: Mishra
authors.affiliation: Jawaharlal Nehru Medical College, Belgaum; and.
authors.forename: Praful Suresh
authors.initials: PS
authors.lastname: Maste
authors.affiliation: Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, India.
authors.forename: George C
authors.initials: GC
authors.lastname: Vilanilam
authors.affiliation: Neurophysiology, National Institute of Mental Health and Neurosciences, Bengaluru;
authors.forename: Talakkad N
authors.initials: TN
authors.lastname: Sathyaprabha
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D066193:Cervical Cord / Q000473:pathology; D002908:Chronic Disease; D019299:Decompression, Surgical; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017887:Ossification of Posterior Longitudinal Ligament / Q000150:complications; D011446:Prospective Studies; D012120:Respiration Disorders / Q000175:diagnosis* / Q000209:etiology*; D013117:Spinal Cord Compression / Q000150:complications* / Q000209:etiology / Q000601:surgery; D013147:Spirometry; D055009:Spondylosis / Q000150:complications; D013223:Statistics as Topic
keywords: CCM = chronic compressive myelopathy; CSM = cervical spondylotic myelopathy; FEV1 = forced expiratory volume in 1 second; FEV1/FVC = ratio of FEV1 to FVC; FVC = forced vital capacity; MVV = maximal voluntary ventilation; OPLL = ossification of the posterior longitudinal ligament; PEFR = peak expiratory flow rate; PFT = pulmonary function test; VC = vital capacity; cervical spondylotic myelopathy; chronic compressive myelopathy; cord compression; pulmonary function test; spirometry; subclinical respiratory depression