THERMOGRAPHIC ANALYSIS OF NEUROVASCULAR INNERVATION FIELDS BY PERIPHERAL NERVES SUPPLYING THE UPPER LIMB SUGGEST DIFFERENT SYMPTOMATIC PATTERNS THAN SOMATOSENSORY DISTRIBUTIONS. Roger J. Allen*; E M. Jefferson; Lisa R. Koshi Physical Therapy, University of Puget Sound, Tacoma, WA PURPOSE: The purpose was to investigate neurovascular innervation patterns of major peripheral nerves supplying the upper limb and compare resulting innervation fields to somatosensory distributions. BACKGROUNDS/SIGNIFICANCE: This study has established that although similar, patterns of neurovascular innervation to the upper limb are different in several notable ways from traditionally known somatosensory patterns. Peripheral neuropathies involving sympathetic efferent nerves may therefore produce symptom patterns that do not match somatosensory distribution fields, and the resulting symptoms should not lead the therapist to conclude the pathology is nonorganic. Median, radial, or ulnar neurovascular involvement may generate these atypical patterns. The consistency of findings between subjects and sample size of the current study now affords presentation of a vasomotor innervation map of the upper extremity for use by clinicians. SUBJECTS: Subjects included 22 female and 10 male adult volunteers ranging in age from 27 to 56 years (x = 35), who reported no history of vascular pathology, peripheral neuropathy, idiopathic limb pain, hypertension, diabetes, cerebrovascular insufficiency, or allergic reactions to amine-type anesthetics. METHODS AND MATERIALS: Nerves investigated included the median, radial, ulnar, medial antibrachial cutaneous, musculocutaneous, and axillary. In a climate controlled chamber at 22oC and 16oC subjects received a series of infiltration method nerve blocks, with 1.8 ml of a 3% Carbocaine hydrochloride, within 1 cm of the nerves most proximal selective location. The anesthetic created local fields of vasodilation by blocking vasomotor sympathetic efferents. Resulting increased surface temperature was imaged thermographically to reveal the innervation field for each nerve. A Kline RU-16ir digital thermogram imaged pre and post-blockade surface temperature fields of the limb. The success and selectivity of each nerve block was validated using Semmes Weinstein monofilament testing, manual muscle testing, and observed limb posturing. For each subject individual nerve blocks were separated by at least 24 hours. ANALYSES: Post-blockade thermographic images were compared to pre-blockade stabilization images. Surface temperature increases of greater than 3 degrees centigrade were mapped for each 4 square millimeter region of the limb, representing the field of hyperemia associated with the neurovascular innervation region for each nerve. RESULTS: Although thermographic evidence of peripheral nerve innervation to the arterial system of the upper limb displayed patterns of marked similarity to somatosensory distributions, notable exceptions were observed. The radial nerve did not appear to innervate any vasculature distal to the wrist in any subjects. The median nerve showed evidence in all subjects of suppling both palmar and dorsal surfaces of the thenar side of the hand. The ulnar nerve appeared to contribute to vascular innervation of the medial forearm. Inconsistencies between subjects was limited to 4 of the 32 subjects displaying variation in the ulnar nerves innervation of vascular activity in digit four. CONCLUSIONS: Peripheral nerves supply the vascular system of the upper extremity in superficial patterns similar to somatosensory distributions, with notable exceptions for the fields of the radial, median, and ulnar nerves. FUNDING SOURCE: University of Puget Sound University Enrichment Committee for travel funding to present findings. KEYWORDS: Neurovascular, Vasomotor innervation, Ischemic pain, Peripheral Neuropathy Copyright 2009 by the American Physical Therapy Association. Requests for reprints should be directed to the corresponding author of the article. Educators, students, and other academic customers may receive permission to reprint copyrighted material from Physical Therapy (ISSN 1538-6724) by contacting the Copyright Clearance Center Inc, 222 Rosewood Dr, Danvers, MA 01923. Other types of customers who want permission to reprint should contact the APTA Editorial Office, Attn: Physical Therapy.