Perhaps one of the more frustrating complications of either ventral or dorsal subaxial surgery involving the C4-C5 level is a postoperative C5 nerve root palsy (C5P). Normal function of the deltoid and biceps brachii is a necessity of daily life, and malfunction of these muscles can have a substantial negative impact on the patient’s life. The worst case scenario is a bilateral dense C5P, which is not a very functional deficit. Despite a relatively vast collection of literature that has investigated C5P, the underlying cause and adequate treatment of it remain obscure.

It is known that C5P can occur from both ventral and dorsal cervical surgery, and in general, the average incidence is approximately 4.6% (1). The average incidence following ventral decompressive surgery is 4.3% (2, 3, 4, 5, 6, 7, 8, 9, 10, 11 and 12), and after dorsal procedures (i.e., laminoplasty), the average incidence is reported to be 4.7% (6,9,10,13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39 and 40). Multiple theories have been developed to explain C5P. They include (a) iatrogenic nerve root injury; (b) segmental spinal cord disorder; (c) radicular artery insufficiency with subsequent ischemia; (d) nerve traction due to spinal cord migration following decompression; and (e) a reperfusion injury to the spinal cord. While one theory may seem plausible in certain cases, the bulk of literature has not concluded a precise, reproducible cause to explain the development of C5P postoperatively for all cases.

C5 root palsies are unilateral in the vast majority of patients (˜90%), (14,21,39,40) and typically occur within the first postoperative week (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39 and 40). Outcome of C5P has been evaluated by many authors (4,7,8,17,18,21,23,24,31, 32, 33 and 34,39,40). Generally, a more severe initial motor deficit results in a worse prognosis in terms of motor recovery. Sakaura et al. (41) compiled the results of 15 publications on postoperative C5Ps and demonstrated that 71% (43 of 58 cases) of patients with muscle motor testing (MMT) of 2 or worse recovered to a useful level compared to 96% of patients (54 of 56) with 3 to 4 MMT who recovered fully. In 2010, Imagama et al. (42) reported on 1,858 laminoplasty patients, 2.3% (N = 43) of whom developed a C5P at a mean of 4.7 days postoperatively. Their results support the previously mentioned association of dense initial motor paralysis and poor prognosis in terms of motor recovery. The time to complete recovery after C5P onset has also been reported. Imagama et al. (42) reported a mean latency between palsy onset to complete recovery of 4.1 months (3 days to 17 months). In the review by Sakaura et al. (41), 25 patients with a severe (MMT of 2 or less) palsy had the following latencies to recovery: up to 3 months in 1 patient (4%), 3 to 6 months in 13 (52%), and 6 to 13 months in 11 (44%). In 23 patients with mild paresis (MMT 3 to 4), the time to recovery was up to 3 months in 11 patients (48%), 3 to 6 months in 7 (30%), and greater to 6 months in 5 (22%).