Nerve Tracing in Juvenile Rats: A Feasible Model for the Study of Brachial Plexus Birth Palsy and Cocontractions?

Brachial plexus birth injuries cause diminished motor function in the upper extremity. The most common sequel is internal rotation contracture. A number of these patients also suffer from cocontractions, preventing the use of an otherwise good passive range of motion in the shoulder. One theory behind the co-contracture problem is that injured nerve fibers grow into distal support tissue not corresponding to the proximal support tissue, resulting in reinnervation of the wrong muscle groups. To further elucidate this hypothesis, we used rat neonates to investigate a possible model for the study of cocontractions in brachial plexus birth injuries. Five-day-old rats were subjected to a crush injury to the C5-C6 roots. After a healing period of 4 weeks, the infraspinatus muscle was injected with Fluoro-Gold. A week later, the animals were perfused and spinal cords harvested and sectioned. Differences in the uptake of Fluoro-Gold and NeuN positive cells of between sides of the spinal cord were recorded. We found a larger amount of Fluoro-Gold positive cells on the uninjured side, while the injured side had positive cells dispersed over a longer area in the craniocaudal direction. Our findings indicate that the method can be used to trace Fluoro-Gold from muscle through a neuroma. Our results also indicate that a neuroma in continuity somewhat prevents the correct connection from being established between the motor neuron pool in the spinal cord and target muscle and that some neurons succumb to a crushing injury. We also present future research ideas.

Structures contributing to the shoulder contracture in brachial plexus birth palsy. An intraoperative biomechanical study.

Internal rotation contracture of the shoulder is a common sequel of the brachial plexus birth palsy. The purpose of this study is to describe the surgical method used in our centre and to measure the effect of sequentially releasing several anatomical structures that have been ascribed as the cause of the contracture. Twenty-four consecutive patients were operated on with an open release. We documented the increase in passive external rotation after each surgical step. We found small gains in passive external rotation when performing coracoidectomy and division of the upper part of the subscapularis tendon; 4° (95% confidence interval [CI] 2°-6° p < 0.01) and 6° (95% CI 4°-8° p < 0.01), respectively. A substantial gain in external rotation occurred when dividing the entire subscapularis tendon, 43° (95% CI 38°-48°, p < 0.01). Our findings indicate that a clinically relevant surgical release of the contracture requires lengthening of the entire subscapularis musculo-tendinous unit.Level of evidence: IV.

Development of the glenohumeral joint after subscapular release and open relocation in children with brachial plexus birth palsy: long-term results in 61 patients.

BACKGROUND: We present the long-term results of remodeling of the glenohumeral joint after open subscapularis elongation and relocation of the humeral head in patients with an internal rotation contracture and joint incongruity due to brachial plexus birth palsy. METHODS: In this before-and-after study, 61 patients who underwent open subscapularis elongation and reduction of the glenohumeral joint were evaluated with respect to joint remodeling, with a mean follow-up period of 10.2 years (range, 7-16 years). The mean age at operation was 3.2 years (range, 8 months to 15 years). Measurements of the percentage of the humeral head anterior to the midscapular line (PHHA), glenoid version, and diameter of the humeral head were recorded using magnetic resonance imaging, comparing the affected joints preoperatively vs. postoperatively (n = 31) and comparing the operated vs. unaffected sides postoperatively (n = 61). RESULTS: The mean increase in PHHA was 27.6 percentage points (95% confidence interval, 22.4-32.7 percentage points; P < .01), from 13.2% to 40.8%. The glenoid retroversion changed by 14.8° (95% confidence interval, 11.1°-18.4°; P < .01), from 25.4° to 10.6°, approaching a normal value. All patients, even those older than 5 years, showed a clear benefit from surgery. CONCLUSIONS: Our study confirms that open subscapularis lengthening with joint repositioning, up to the age of 5 years, gives consistent remodeling of incongruent shoulders with surprisingly small differences between the operated and unaffected shoulders at long-term follow-up. The findings indicate that open reduction is useful also in adolescents and challenges the notion that older children should be treated with derotational humeral osteotomy.

Cortical activity and hand function restoration in a patient after spinal cord surgery.

BACKGROUND: Following a motorcycle accident, a 9-year-old boy experienced a complete right-sided (dominant) arm and hand paralysis with total sensory loss, Horner syndrome and severe constant pain. This study assessed the long-term outcome of spinal cord surgery undertaken on the patient, focusing on the restored hand function and related cortical activity. The study follows on from previous reports on the same patient. INVESTIGATIONS: Clinical functional and electrophysiological examinations. Functional MRI of cortical activity. DIAGNOSIS: Complete brachial plexus (C5-T1) avulsion from the spinal cord. MANAGEMENT: Spinal cord surgery to restore motor trajectories.