A Randomized, Prospective Study Determining the Impact of Prophylactic Bilateral Foraminotomy During Cervical Decompression on C5 Palsy

Introduction:

C5 palsy (C5P) is a well-known, although rare complication of cervical spine decompression surgery.1,2 In severe forms, C5P causes debilitating upper extremity weakness involving the deltoids and/or biceps brachii muscles, ultimately diminishing these patients' quality of life.3 Furthermore, about half of patients with C5P present with sensory deficits and/or intractable pain in addition to the muscle weakness.5 Fortunately, almost all cases of C5P present unilaterally. The deficit is typically quantified and diagnosed using each patient's manual muscle test (MMT) score (rating 0-5). The American Medical Association impairment rating guide grades the MMT as follows: Grade 0 = no perceptible muscle contraction; Grade 1 = muscle contraction palpable, but no motion; Grade 2 = motion of the part only with gravity reduced; Grade 3 = muscle can hold the part in the test position against gravity alone; Grade 4 = patient can move the part through the full range of active motion against "some" resistance; Grade 5 = patient can move the part through the full active range of motion against "full" resistance. C5P is defined as: a reduction of at least 1 in deltoid and/or biceps brachii scores compared to preoperative scores, without any deterioration of myelopathic symptoms.5

Although a uniform understanding of the etiology and mechanism of C5P is not yet established, certain hypotheses have gained recognition. One prominent hypothesis, called the tethering phenomenon, suggests that following decompression, posterior shift of the cord produces traction on the nerve root resulting in a nerve root lesion. Other, less agreed upon hypotheses include: inadvertent injury to the nerve root during surgery, spinal cord ischemia, segmental spinal cord disorder, and reperfusion injury of the spinal cord. As the pathogenesis of C5P is uncovered, concerted efforts to minimize the incidence of this unfortunate complication have been undertaken.5

Prophylactic bilateral foraminotomy at the C5 level during cervical decompression surgery has been studied recently with the hope that it will minimize the risk of developing a C5 nerve root palsy postoperatively.6,7,8 Although the current literature provides some support for this claim, there are insufficient data establishing this technique as a proven measure to reduce the incidence of C5P. In the present study, we seek to evaluate the effect of bilateral foraminotomy on postoperative C5P incidence rates.

Background: