Inherited neuropathies.

With a prevalence of 1 in 2500 people, inherited peripheral nerve diseases, collectively called Charcot-Marie-Tooth disease (CMT), are among the most common inherited neurologic disorders. Patients with CMT typically present with chronic muscle weakness and atrophy in limbs, sensory loss in the feet and hands, and foot deformities. Clinical similarities between patients often require genetic testing to achieve a precise diagnosis. In this article, the author reviews the clinical and pathologic features of CMT, and demonstrates how electrodiagnostic and genetic tools are used to assist in the diagnosis and symptomatic management of the diseases. Several cases are presented to illustrate the diagnostic processes.

Electrophysiologic evidence of polyneuropathy in a cat with signs of bilateral brachial plexus neuropathy.

CASE DESCRIPTION: A 2-year-old spayed female domestic shorthair cat was examined because of bilateral thoracic limb weakness of acute onset. CLINICAL FINDINGS: Clinical signs included muscle atrophy, paresis, depressed spinal reflexes, hyperesthesia of the thoracic limbs, and reduced jaw muscle tone. Pelvic limb reflexes were normal. Results of a neurologic examination were suggestive of multifocal lesions involving both brachial plexuses and the trigeminal nerves. Abnormal nerve conduction across the brachial plexus and delayed late potentials were found on electrodiagnostic testing, and diffuse subclinical involvement of other regions of the peripheral nervous system was confirmed on the basis of abnormal electromyographic findings for the masticatory muscles and conduction block of the peroneal nerve. TREATMENT AND OUTCOME: No specific treatments were given, and neurologic signs resolved within a month. A relapse occurred 2 months after the first episode, with clinical signs affecting both the pelvic and the thoracic limbs on this occasion. Again, the condition resolved without specific treatment, and 13 months after the initial episode, the cat reportedly was normal. CONCLUSIONS AND CLINICAL RELEVANCE: Findings suggested that brachial plexus neuropathy can be a multifocal disease in cats, even if clinically apparent neurologic deficits are initially subtle or absent, and that electrodiagnostic techniques can be used to identify subclinical involvement of the peripheral nerves.

Shoulder and elbow kinematics during the Mallet score in obstetrical brachial plexus palsy.

BACKGROUND: The physical signs of obstetrical brachial plexus palsy range from temporary upper-limb dysfunction to a lifelong impairment and deformity in one arm. The aim of this study was to analyze the kinematics of the upper limb and to evaluate the contribution of glenohumeral and scapulothoracic joints of obstetrical brachial plexus palsy children. METHODS: Six children participated in this study: 2 males and 4 females with a mean age of 11.7years. Three patients had a C5, C6 lesion and 3 had a C5, C6, C7 lesion. They were asked to perform five tasks based on the Mallet scale and the kinematic data were collected using the Fastrak electromagnetic tracking device. FINDINGS: The scapulothoracic protraction and posterior tilt were significantly increased in the involved limb during the hand to mouth task (p=0.006 and p=0.015 respectively). The scapulothoracic Protraction/glenohumeral Elevation ratio was significantly increased in the involved limb during the hand to neck task (p=0.041) and the elevation task (p=0.015). The ratios of scapulothoracic Tilt on the three glenohumeral excursion angles were significantly increased during the hand to mouth task (p≤0.041). The scapulothoracic Mediolateral/glenohumeral Elevation ratio was significantly increased in the involved limb during the elevation task (p=0.038). The glenohumeral elevation excursion was significantly decreased in the involved limb during the hand to neck task (p<0.001) and the elevation task (p=0.0003). INTERPRETATION: This study gives us information about the greater contribution of the scapulothoracic joint to shoulder motion for affected arm of obstetrical brachial plexus palsy patients compared to their unaffected arm. Kinematic analysis could be useful in shoulder motion evaluation during the Mallet score and to evaluate outcomes after surgery.

Neonatal brachial plexus palsy. Outcome of absent biceps function at three months of age.

BACKGROUND: An important prognostic factor in neonatal brachial plexus palsy is the time interval to biceps muscle recovery. Although the natural history is not clear, biceps muscle recovery after more than three months of age has been used to predict poor long-term shoulder function. The absence of biceps muscle function at three months of age has been adopted as an indication for early brachial plexus microsurgery, in an attempt to improve recovery. To provide a benchmark for outcome comparison, the long-term outcome of patients with absent biceps muscle function at three months of age was studied. METHODS: Between 1980 and 1992, 170 patients with neonatal brachial plexus palsy were entered into a prospective study in which details of the birth and serial clinical examinations were recorded. Patients were grouped according to the level of injury and the time interval to biceps muscle recovery. Twenty-nine patients were observed to have absent biceps muscle function at three months of age. Twenty-eight of those patients were available for long-term followup at a mean age of eleven years and one month. At the time of follow-up, patients answered a questionnaire and underwent manual muscle strength testing, sensory evaluation, and grading of their shoulder function according to Gilbert's modification of the Mallet score, in which the function was graded as II, III, or IV with class I (no function) and V (normal) eliminated. The level of injury and the time that biceps muscle function returned were compared with the final outcomes. RESULTS: The level of injury was C5-C6 in thirteen (46%) of our twenty-eight patients with absent biceps muscle function at three months of age, C5-C7 in five (18%), and pan-plexus (C5-T1) in ten (36%). Biceps contraction was observed by six months of age in twenty patients (71%), including all thirteen patients with a C5-C6 level of injury. Twenty-two patients did not have surgery on the brachial plexus, but nine of those patients had subsequent orthopaedic procedures. At the time of follow-up, twenty-seven of the twenty-eight patients had at least antigravity biceps muscle function. Patients who regained biceps muscle function between three and six months of age had better scores for abduction (p = 0.04) and for hand-to-neck (p = 0.05) and hand-to-back (p < 0.001) function than did patients who regained biceps muscle function after six months of age. Patients with a C5-C6 lesion had better scores for external rotation (p = 0.04) and for hand-to-neck (p = 0.05), hand-to-mouth (p < 0.01), and hand-to-back (p < 0.001) function than did patients with a pan-plexus lesion. Twelve (55%) of the twenty-two patients who did not have brachial plexus surgery had a class-IV shoulder (good function) according to the modified Mallet score. Of the twelve patients with a C5-C6 level of injury who did not have brachial plexus surgery, eight had a class-IV shoulder. CONCLUSIONS: This study indicated associations between prolonged neurological recovery and a more extensive level of injury and worse long-term shoulder function. Patients with a C5-C6 injury and absent biceps muscle function at three months of age often have good long-term shoulder function without brachial plexus surgery.

Self-mutilation in children with obstetric brachial plexus palsy.

In a prospective study, the incidence and clinical presentation of self-mutilation was documented in 127 consecutive cases of obstetric brachial plexus injury. Six out of the 127 cases (4.7%) had clinical evidence of self-mutilation. The incidence of self-mutilation was much higher among children with total palsy (4/37) than Erb's palsy (2/90). All affected children were able to bring the mutilated hand or forearm to the mouth without assistance from the contralateral normal limb. Mutilation in patients with total palsy was generally severe and usually involved biting the tips of the digits. However, mutilation in patients with upper (Erb's) palsy was mild in degree and tended to involve the dorsum of the hand. Similarity between human self-mutilation and animal autotomy following denervation are discussed along with the different theories explaining the mechanism of this abnormal behaviour.

Etiology, treatment, and prevention of athletic "stingers".

Stingers or burners are common in athletes, especially football players. They represent a traction, compression, or direct blow to the upper roots of the brachial plexus. They are usually transient and resolve quickly. Cervical canal stenosis with concurrent degenerative disc disease may predispose an athlete to this injury. Return-to-play criteria are largely based on the number of previous episodes and the duration of symptoms. These criteria also require appropriate consideration of any underlying pathological conditions. Appropriate counseling, including modification of tackling and addition of protective gear, in conjunction with complete rehabilitation, may be effective in preventing this condition or decreasing the rate of recurrence. The athlete, family, and coaches need to understand that recurrence remains unpredictable.

Acute sports-related spinal cord injury: contemporary management principles.

Improvements in helmet and equipment design have led to significant decreases in overall injury incidence, but no available helmet can prevent catastrophic injury to the neck and cervical spine. The most effective strategy for preventing this type of injury appears to be careful instruction, training, and regulations designed to eliminate head-first contact. The incidence of football-related quadriplegia has decreased from a peak of 13 cases per one million players between 1976 and 1980 to 3 per million from 1991 to 1993, mostly as a result of systematic research and an organized effort to eliminate high-risk behavior. An episode of transient quadriparesis does not appear to be a risk factor for catastrophic spinal cord injury. Torg reported that 0 of 117 quadriplegics in the National Football Head and Neck Injuries Registry recalled a prior episode of transient quadriparesis, and 0 of the 45 patients originally studied in his transient quadriparesis cohort have subsequently suffered quadriplegia. The significance of developmental spinal stenosis is unclear. Plain radiographic identification of a narrow spinal canal in a player sustaining cervical cord neurapraxia warrants further evaluation by MRI to rule out functional stenosis. The presence of actual cord deformation or compression on MRI should preclude participation in high-risk contact or collision sports.

Primary restoration of elbow flexion in adult post-traumatic plexopathy patients.

Restoration of elbow flexion is one of the priorities in brachial plexus palsy, as this function brings the hand to the mouth. This study analyses the results of musculocutaneous nerve reconstruction in 194 patients with devastating paralysis. Results were analyzed in relation to denervation time, severity score, length of nerve grafts, and donor nerves used. Between 1978 and 2006, 194 post-traumatic plexopathy patients underwent musculocutaneous nerve reconstruction. 298 motor donors were used in 175 patients while 19 patients had microneurolysis. There were 104 intraplexus motor donors; 124 intercostal nerves were transferred in 39 patients; direct coaptation was performed in 31 patients and three or more intercostals were transferred in 33 patients; 16 patients underwent musculocutaneous to musculocutaneous repair. 144 patients had interposition nerve grafts. The mean follow-up was 4.48 ± 2.78 years. Results were good or excellent (≥M3+) in 52.53% of patients with more than 70° of elbow flexion. Patients, who were operated on less than 4 months from injury, with high severity score, attained significant better results than late cases with multiple root avulsions. Intraplexus donors have direct influence on biceps recovery, achieving significant better results than extraplexus donors. Intercostal nerves are an alternative source in avulsion injuries. The use of 3 intercostals with direct coaptation yielded optimal elbow flexion. Musculocutaneous nerve reconstruction is one of the priorities in upper limb reanimation. Functional outcomes are influenced by the age of the patient, severity of plexus lesion, denervation time, and type of reconstruction. Early surgery is recommended.