PATTERNS OF VASCULAR INNERVATION FROM THE SIX MAJOR PERIPHERAL NERVES SUPPLYING THE UPPER LIMB?

Abstract

PURPOSE/HYPOTHESIS: To establish a comprehensive map of major peripheral nerve innervation patterns to the arterial system of the upper limb? NUMBER OF SUBJECTS: Thirty-two adult volunteers (22 females, 10 males), ranging in age from 27 to 56 years (x = 35), reporting no history of idiopathic limb pain, vascular pathology, peripheral neuropathy, diabetes, hypertension, cerebrovascular insufficiency, or hypersensitive reactions to amine anesthetics. MATERIALS/METHODS: Peripheral nerves investigated include the median, radial, ulnar, medial antibrachial cutaneous, musculocutaneous, and axillary. In a climate controlled chamber (22oC and 16oC) subjects received a series of nerve blocks, using infiltration of Carbocaine hydrochloride (1.8 ml of a 3% solution), within 1 cm of the expected location of the nerve??s most proximal selective point. Carbocaine blocked sympathetic efferents, creating local fields of vasodilation and increased surface temperature which was imaged thermographically to reveal the innervation field for each nerve. Anterior and posterior images of the limb were taken pre- and post-blockade using a Kline RU-16ir digital thermogram. Semmes Weinstein monofilament testing, manual muscle testing, and observed limb posturing validated success and selectivity of each nerve block. Individual nerves of each subject were tested on separate days, with at least 24 hours separating blocks. “ RESULTS: Vasomotor innervation patterns for each nerve showed strong similarity to patterns of somatosensory innervation with notable exceptions. There was no evidence of radial nerve innervation to the vasculature of the hand. The median nerve appeared to supply both palmar and dorsal surfaces of the thenar side of the hand. The ulnar nerve displayed influence over some vascular activity of the medial forearm. Variation between subjects was limited to 4 of the 32 subjects showing idiosyncracies in the ulnar nerves contribution to vascular activity of digit four. CONCLUSIONS: Consistent with prior studies using smaller sample sizes, this investigation supports the conclusion that patterns of vasomotor innervation of peripheral nerves supplying the upper limb are similar to somatosensory distributions, with notable exceptions for the fields of the radial, median, and ulnar nerves. CLINICAL RELEVANCE: Peripheral neuropathies influencing autonomic efferents may produce symptom patterns that are slightly different from those expected from knowledge of somatosensory distributions. Atypical patterns resulting from neurovascular ischemia may appear with radial, median, or ulnar nerve involvement and should not be mistaken as nonorganic in origin. The present studys sample size and intersubject consistency in displayed patterns of hyperemia allows the creation of a complete charting of the upper limbs vasomotor innervation fields.