Correlation among lesion level, muscle strength and hand function in cervical spinal cord injury

Abstract

Background: Few epidemiological data are available regarding distribution of cervical spinal cord injury with respect to level of lesion and the relationship between the neurological level of lesion and residual hand function. Such data are important to evaluate the relevance of innovative therapeutic approaches, and to plan prospective clinical trials.

Aim: To examine the frequency distribution of neurological level of lesion and to investigate the correlation among level, active muscles in the arm and the relation to hand function.

Design: Cross-sectional study.

Setting: Two spinal units in the Lombardy region of Italy.

Population: Patients with cervical spinal cord lesion.

Methods: Consecutive records, taken from an 8-year interval of admission to either spinal unit, of patients with a cervical spinal cord lesion were examined, and individuals with a C5 to C7 neurological level of lesion were called in for clinical examination. The arm muscles were evaluated according to the International Classification for Surgery of the Hand in Tetraplegia (ICSHT), and hand function was tested with the Action Research Arm Test (ARAT). A correlation analysis was made of the ICSHT, ARAT and neurological level of lesion.

Results: In 253 clinical records we found the most frequent lesions to be C5 (21%), C6 (31%) and C7 (21%); 76 of these patients were enrolled for a clinical evaluation. Both ICSHT (Spearmans' rho=0.6; P<0.001) and ARAT (rho=0.2; P<0.05) were poorly correlated with the neurological level of lesion. ARAT was also poorly correlated with the ICSHT group (rho=0.5; P<0.001).

Conclusion: Our study suggests that 73% of tetraplegic subjects have a neurological level of lesion between C5 and C7, and that it is not possible to accurately predict residual hand function from the level of lesion obtained from the clinical records, or from an ICSHT evaluation.

Clinical rehabilitation impact: The results of our work show that a large number of patients with cervical spinal cord lesion have impaired hand function. Residual hand function must be assessed with specific functional tests; it cannot be derived simply from a lesion's neurological level.