Perforasomes of the Nerves of the Upper Extremity
Suhail K Mithani, MD; Department of Orthopaedic Surgery, Duke University, Durham, NC; Steven M. Koehler, MD; Orthopaedic Surgery, Duke University, Durham, NC
Introduction:The purpose was to examine the extrinsic perforator blood supply to the major peripheral nerves of the upper extremity and to categorize the perforasomes of the nerves.
Materials & Methods:Total limb perfusion of the arterial system was performed with a gelatin-red lead oxide mixture in cadaveric upper limbs. The perforating vessels to the radial, median and ulnar nerves were identified, confirmed with fluoroscopy, dissected, and distances to major anatomic landmarks were measured. Additional limbsÕ nerves were dissected and source arteries were selectively cannulated and injected with different color inks to assess specific perforator contribution to extrinsic nerve perfusion. The nerves were then sectioned and examined for internal staining. The perfusion of each nerve was then calculated among all specimens.
Results: The radial, median and ulnar nerve perforators were mapped (Figure 1). The perforasomes of radial, median and ulnar nerves were mapped (Figure 2). The distal portion of the superficial radial nerve (SRN) was hypoperfused. The posterior interosseous nerve (PIN) was hypoperfused at the supinator muscle and distally. At and proximal to the carpal tunnel, the median nerve was hypovascular. Proximally, 25% of the median nerve in the forearm was hypovascular, corresponding to the pronator teres. At GuyonÕs canal and the flexor carpi ulnaris (FCU) the ulnar nerve was hypovascular.
Conclusions:Our findings demonstrate that peripheral nerves can be divided into perforasomes. Each perforasome carries a specific flow pattern, which does not overlap. The extrinsic perfusion of peripheral nerves is highly segmental. Hypoperfusion within the nerves correspond to common sites of compression: carpal tunnel and pronator teres for the median nerve, supinator for the PIN, distally for the SRN, and GuyonÕs canal and the FCU for the ulnar nerve. Our data suggests that the sites of common compression neuropathies are potentially predisposed to ischemia based on their lack of extrinsic vascularization, warranting further study to investigate this correlation.
Figure 1: Upper Extremity Nerve Perforators
Figure 2: Upper Extremity Nerve Perforasomes and Perfusion
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