Two patients with congenital cervical spinal muscular atrophy and arthrogryposis limited to the upper limbs are reported from the Hospital Enschede, The Netherlands, and University Hospital RWTH Aachen, Germany. A girl, aged 1 year, born with congenital arthrogryposis multiplex, had severe bilateral hypotonia, weakness and wasting of shoulder girdles, arms and hands. Tendon reflexes were absent in the upper limbs. EMG of the triceps was silent, and a biopsy showed severe neurogenic muscle atrophy. A 31 year old man, born with severe muscle weakness and congenital contractures of the upper limbs, had herniations of the intervertebral discs C2-C4 and C5-C7 but normal signal intensity of the cord on T2-weighted images of the MRI. Both patients had normal sensory modalities, and lower limbs were not involved. [1]

COMMENT. The absence of sensory deficits and normal motor nerve conduction velocities point to involvement of the anterior horn cells. The etiology of the prenatal pathology with loss of anterior horn cells in cases of neurogenic arthrogryposis is unknown, except for one case cited of rubella exposure. The limitation to the upper limbs is unusual.