Detailed features and prognostic factors of twenty-three patients with drop finger caused by cervical radiculopathy: a retrospective multicentre study.

PURPOSE: It has been reported that C7 and C8 nerve root impairment can cause drop finger; however, the clinical characteristics of each injured nerve root and post-operative outcomes remain unclear. This study aimed to investigate the detailed features and surgery-related prognostic factors of drop finger caused by cervical radiculopathy. METHODS: We retrospectively investigated the clinical characteristics, paralysis patterns and surgery-related prognostic factors of 23 patients with drop finger caused by cervical radiculopathy who underwent posterior cervical foraminotomy. We classified paralysis into three patterns based on the fingers predominantly exhibiting extensor digitorum communis (EDC) muscle weakness: index finger side-dominant, middle and ring fingers-dominant and little finger side-dominant. RESULTS: The aetiologies were cervical disc hernia (CDH) in ten patients, cervical spondylotic radiculopathy (CSR) in eight and both CDH and CSR in five. The levels of the decompressed root were C7 in one patient, C8 in 11 and both C7 and C8 in 11. Scapular pain was frequently observed as the initial symptom (78%), especially in patients with only C8 nerve root disorder (91%). Drop finger recovered to a score of ≥ 3 on manual muscle testing in 17 patients; patients with the little finger side-dominant pattern tended to have poor recoveries. Patients with CDH improved significantly than those with CSR or both CDH and CSR (p < 0.05). CONCLUSIONS: Good surgical recovery of drop finger can be expected in patients with CDH and in those with index fingers-dominant and middle and ring fingers-dominant patterns.