Arthrogryposis multiplex congenita: histochemical study of biopsied muscles

Benign infantile neurogenic muscle atrophy predominantly involving the upper extremities

An eight year-old girl was first noted to be hypotonic at 4 months of age. She had a delay in achieving developmental milestones and showed apparent weakness predominantly affecting muscles of the upper extremities. In the left biceps brachii muscle biopsy at the age of 5 months, there were groups of atrophic fibers and marked fiber type grouping, but intramuscular nerves were well myelinated and there were few type 2C fibers. She improved with age and learned to walk at 1 year and 4 months and had minimal weakness of the forearm muscles and mild atrophy of the muscles of the right upper extremity. She recently developed a mild scoliosis. Since the EMG was not neurogenic and no mutations were found in the survival motor neuron (SMN) gene, we believe that she does not have a degenerative neurogenic disorder but rather has an abnormal innervation of the skeletal muscles due either to anterior horn cell dysgenesis or anomalous peripheral nerve branching.

Arthrogryposis multiplex congenita in Western Australia

OBJECTIVE

Determination of the prevalence of arthrogryposis multiplex congenita in Western Australia as well as the causes of the condition. Overseas reports varied considerably and no such survey had been conducted in Western Australia.

METHODOLOGY

Case names were obtained from various registers and records as well as from private practitioners covering the 14 years birth cohort between 1980 and 1993. The records, and where possible the patients, were seen by one of the authors. Diagnosis was further established through relevant investigation where possible.

RESULTS

Thirty cases were identified, giving a birth prevalence of approximately 1 in 12000. In nine cases there were significant abnormalities of the central nervous system, in seven cases anterior horn cell and/or peripheral nervous involvement was the cause and in three there was primary muscle disease. The remaining 11 had various syndromes for which no definite neuropathological lesions could be demonstrated, but most of these had syndromes such as distal arthrogryposis or amyoplasia. Mortality was 37%. Talipes occurred in 23 of 30 cases. Early intervention and, in more severe cases, radical surgical intervention was the management adopted in most cases.

CONCLUSION

The birth prevalence of arthrogryposis in Western Australia is somewhat less than that reported in Canada and Finland but somewhat greater than the Edinburgh figures, which appear to be the extremes quoted in the literature. Prognosis is worse in cases with serious central nervous system involvement and/or chest involvement, and better in cases of localised arthrogryposis (e.g. distal), as well as in the specific syndrome of amyoplasia as described by Hall.

Deficiency of a skeletal muscle isoform of alpha-actinin (alpha-actinin-3) in merosin-positive congenital muscular dystrophy

A subset of patients with congenital muscular dystrophy (CMD) are deficient for the extracellular matrix protein, merosin. Although the aetiology of merosin-positive CMD is as yet unknown, abnormalities of other structural muscle-specific proteins are likely to be involved. The alpha-actinins are actin-binding proteins related to dystrophin. We studied expression of the skeletal muscle isoforms of alpha-actinin (alpha-actinin-2 and alpha-actinin-3) in muscle biopsies from 12 patients with pure CMD (including one with a merosin abnormality), two with unclassified CMD and central nervous system (CNS) involvement, and three with other neuromuscular disorders. Four specimens exhibited deficient alpha-actinin-3 staining by immunofluorescence and/or Western blot analysis. In one, this pattern may be a secondary consequence of marked type 1 fibre predominance, but the other three biopsies contained abundant type 2 fibres where alpha-actinin-3 is normally expressed. Three alpha-actinin-3-deficient patients had pure CMD and presented in the newborn period with muscle weakness, hypotonia and arthrogryposis. The fourth had a dystrophic muscle biopsy and CNS involvement. These results suggest that deficiency of alpha-actinin-3 may be a marker for a subset of patients with CMD. It remains to be determined whether the deficiency of alpha-actinin-3 reflects ACTN3 gene mutations or is a secondary phenomenon.

Congenital focal muscle dysplasia in the lower extremities from probable abnormal innervation: a case report

A two-year-seven-month-old girl with pes equinovarus congenita, muscle hypotonia and weakness limited to the lower extremities is presented. Upon admission to our hospital, she could stand with support but could not walk alone. Serum creatine kinase level was normal and the electromyogram was nondiagnostic. The muscle CT disclosed an almost total absence of bilateral vastus lateralis and medialis, rectus femoris and gastrocnemius muscles. The biopsied vastus lateralis muscle was almost completely replaced by fat tissue, and a small amount of muscle tissue showed uniform type 1 fiber and an aggregate of atrophic fibers in one fascicle. Because of an absence of progressive muscle weakness and neurogenic EMG findings, the authors conclude that the muscle pathology was due to the congenital anomalous condition of probable abnormal innervation to developing muscles.

The diagnostic management of newborns with congenital contractures: a nosologic study of 75 cases

A prospective clinical study is presented of 75 patients with multiple congenital contractures. With the data from medical history, child neurologic examinations, laboratory tests including chromosome and dermatoglyphic analysis, and neuropathology in 23 cases with perinatal death, a nosological or syndromal diagnosis was made in 61 cases. These cases were classified by localization of causal pathology in the categories "cerebral dysgenesis", spinal cord defects, neuromuscular disorders and miscellaneous disorders without muscle weakness. Following this concept, the various modes of inheritance of specific disorders presenting with congenital contractures, as well as possibilities for prenatal diagnosis by ultrasonography are discussed. A guideline for the child neurologic evaluation of infants with congenital contractures is proposed. It is concluded that: 1) specification of the causal lesion and proper classification of disorders with congenital contractures is crucial for genetic counseling, (prenatal) diagnosis and management; 2) the analysis of dermatoglyphics in differential diagnosis of congenital contractures should be restudied; and 3) more study and experience is required in the observation of abnormal or decreased fetal movements by ultrasonography.

Hereditary peroneal muscular atrophy in the mouse: an experimental model for congenital contractures (arthrogryposis)

A new mutant, peroneal muscular atrophy (pma) mouse in CF#1 strain has an autosomal recessively inherited equinovarus (club foot deformity) of the hind legs because of the absence of the common peroneal nerve branch of the sciatic nerve. We found the peroneal muscles were hypoplastic with histochemical and electron microscopic characteristics of fetal muscle. The anterior horn cells in the spinal cord were not reduced in number and they appeared to be normal. The density and size of the myelinated fibers in the anterior spinal roots of L3, L4, and L5 and the sciatic nerve in the affected side were not different from those in the unaffected. Therefore, the absence of the common peroneal nerve in the pma mouse is thought to result from the misdirection of these nerve bundles into other peripheral nerves. As the anomalous condition was present at birth with no progression, the pma mouse may be an experimental model for the study of arthrogryposis multiplex congenita or club foot deformity, and may lead to the understanding of the muscle and nerve interaction during development.