Transfer of the Distal Anterior Interosseous Nerve for Thumb Motion Reconstruction in Radial Nerve Paralysis.

PURPOSE: With nerve or tendon surgery, the results of thumb reconstruction to treat radial nerve paralysis are suboptimal. The goals of this study were to describe the anatomy of the deep branch of the posterior interosseous nerve (PIN) to the thumb extensor muscles (DBPIN), and to report the clinical results of transferring the distal anterior interosseous nerve (DAIN) to the DBPIN. METHODS: The PIN was dissected in 12 fresh upper limbs. Myelinated nerve fibers in the DBPIN and DAIN were counted. Five patients with radial nerve paralysis underwent transfer of the motor branch to the flexor carpi radialis to the PIN and a motor branch of the pronator teres to the extensor carpi radialis brevis. In addition, these patients had selective reconstruction of thumb motion by transferring the DAIN to the DBPIN, through either a combined volar and dorsal approach (n = 2) or a single dorsal approach (n = 3) with division of the interosseous membrane. RESULTS: At the origin of the abductor pollicis longus, the DBPIN divided into a lateral branch that innervated the abductor pollicis longus and extensor pollicis brevis, and a medial branch that innervated the extensor pollicis longus and extensor index proprius. The number of myelinated nerve fibers in the DAIN corresponded to 65% of that of the DBPIN. In each of the 5 patients, full thumb motion at the trapeziometacarpal joint was restored with no, or minimal, extension lag at the metacarpophalangeal (MCP) joint. CONCLUSIONS: The anatomy of the DBPIN is predictable. Transferring the DAIN to the DBPIN is feasible through a single dorsal approach, allowing full recovery of thumb motion. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic V.

Distal pronator teres motor branch transfer for wrist extension restoration in radial nerve paralysis.

OBJECTIVE: The authors describe the anatomy of the motor branches of the pronator teres (PT) as it relates to transferring the nerve of the extensor carpi radialis brevis (ECRB) to restore wrist extension in patients with radial nerve paralysis. They describe their anatomical cadaveric findings and report the results of their nerve transfer technique in several patients followed for at least 24 months postoperatively. METHODS: The authors dissected both upper limbs of 16 fresh cadavers. In 6 patients undergoing nerve surgery on the elbow, they dissected the branches of the median nerve and confirmed their identity by electrical stimulation. Of these 6 patients, 5 had had a radial nerve injury lasting 7-12 months, underwent transfer of the distal PT motor branch to the ECRB, and were followed for at least 24 months. RESULTS: The PT was innervated by two branches: a proximal branch, arising at a distance between 0 and 40 mm distal to the medial epicondyle, responsible for PT superficial head innervation, and a distal motor branch, emerging from the anterior side of the median nerve at a distance between 25 and 60 mm distal to the medial epicondyle. The distal motor branch of the PT traveled approximately 30 mm along the anterior side of the median nerve; just before the median nerve passed between the PT heads, it bifurcated to innervate the deep head and distal part of the superficial head of the PT. In 30% of the cadaver limbs, the proximal and distal PT branches converged into a single trunk distal to the medial epicondyle, while they converged into a single branch proximal to it in 70% of the limbs. The proximal and distal motor branches of the PT and the nerve to the ECRB had an average of 646, 599, and 457 myelinated fibers, respectively.All patients recovered full range of wrist flexion-extension, grade M4 strength on the British Medical Research Council scale. Grasp strength recovery achieved almost 50% of the strength of the contralateral side. All patients could maintain their wrist in extension while performing grasp measurements. CONCLUSIONS: The distal PT motor branch is suitable for reinnervation of the ECRB in radial nerve paralysis, for as long as 7-12 months postinjury.

Neonatal hypoxic-ischemic encephalopathy reduces c-Fos activation in the rat hippocampus: evidence of a long-lasting effect.

The effect of neonatal hypoxic-ischemic encephalopathy (HIE) on maturation of nociceptive pathways has been sparsely explored. To investigate whether neonatal HIE alters neuronal activity, nociceptive behavior, and serum neuroplasticity mediators (brain-derived neurotrophic factor [BDNF] and tumor necrosis factor-α [TNF]) in the short, medium, and long term. Neonate male Wistar rats were randomized to receive a brain insult that could be either ischemic (left carotid artery ligation [LCAL]), hypoxic (8% oxygen chamber), hypoxic-ischemic (LCAL and hypoxic chamber), sham-ischemic, or sham-hypoxic. Neuronal activity (c-Fos activation at region CA1 and dentate gyrus of the hippocampus), nociceptive behavior (von Frey, tail-flick, and hot-plate tests), neuroplasticity mediators (BDNF, TNF), and a cellular injury marker (lactase dehydrogenase [LDH]) were assessed in blood serum 14, 30, and 60 days after birth. Neonatal HIE persistently reduced c-Fos activation in the ipsilateral hippocampal region CA1; however, contralateral c-Fos reduction appeared only 7 weeks after the event. Neonatal HIE acutely reduced the paw withdrawal threshold (von Frey test), but this returned to normal by the 30th postnatal day. Hypoxia reduced serum LDH levels. Serum neuroplasticity mediators increased with age, and neonatal HIE did not affect their ontogeny. Neonatal HIE-induced reduction in neuronal activity occurs acutely in the ipsilateral hippocampal region CA1 and persists for at least 60 days, but the contralateral effect of the insult is delayed. Alterations in the nociceptive response are acute and self-limited. Serum neuroplasticity mediators increase with age, and remain unaffected by HIE.

Transfer of the distal terminal motor branch of the extensor carpi radialis brevis to the nerve of the flexor pollicis longus: an anatomic study and clinical application in a tetraplegic patient.

BACKGROUND: In tetraplegics, thumb and finger motion traditionally has been reconstructed via orthopedic procedures. Although rarely used, nerve transfers are a viable method for reconstruction in tetraplegia. OBJECTIVE: To investigate the anatomic feasibility of transferring the distal branch of the extensor carpi radialis brevis (ECRB) to the flexor pollicis longus (FPL) nerve and to report our first clinical case. METHODS: We studied the motor branch of the ECRB and FPL in 14 cadaveric upper limbs. Subsequently, a 24-year-old tetraplegic man with preserved motion in his shoulder, elbow, wrist, and finger extension, but paralysis of thumb and finger flexion underwent surgery. Seven months after trauma, we transferred the brachialis muscle with a tendon graft to the flexor digitorum profundus. The distal nerve of the ECRB was transferred to the FPL nerve. RESULTS: The branch to the ECRB entered the muscle in its anterior and proximal third. After sending out a first collateral, the nerve runs for 2.4 cm alongside the muscle and bifurcates intramuscularly. A main branch from the anterior interosseous nerve, which entered the muscle 3 cm from its origin on the radius, innervated the FPL. The ECRB and FPL nerves had similar diameters (∼1 mm) and numbers of myelinated fibers (∼180). In our patient, 14 months after surgery, pinching and grasping were restored and measured 2 and 8 kg strength, respectively. CONCLUSION: Transfer of the ECRB distal branch to the FPL is a viable option to reconstruct thumb flexion.

Transfer of axillary nerve branches to reconstruct elbow extension in tetraplegics: a laboratory investigation of surgical feasibility.

In spinal cord injuries at the C6 level, elbow extension is lost and needs reconstruction. Traditionally, elbow extension has been reconstructed by muscle transfers, which improve function only moderately. We have hypothesized that outcomes could be ameliorated by nerve transfers rather than muscle transfers. We anatomically investigated nerve branches to the teres minor and posterior deltoid as donors for transfer to triceps motor branches. In eight formalin-fixed cadavers, the axillary nerve, the teres minor branch, the posterior deltoid branch, the triceps long and upper medial head motor branches, and the thoracodorsal nerve were dissected bilaterally, their diameters measured and their myelinated fibers counted. To simulate surgery, using an axillary approach in two fresh cadavers, we transferred the teres minor or the posterior deltoid branch to the triceps long head and to the thoracodorsal nerve. The posterior division of the axillary nerve gave off the teres minor motor branch and then the branch to the posterior deltoid, terminating as the superior lateral brachial cutaneous nerve. The diameters of the teres minor motor branch, posterior deltoid, triceps long and upper medial head branches, and the thoracodorsal nerve all were ∼2 mm, with minimal variation. The nerves varied little in their numbers of myelinated fibers, being consistently about 1,000. Via an axillary approach, either the teres minor or the posterior deltoid branch could be transferred directly to the thoracodorsal nerve or to triceps branches without any tension.