Rigid spine syndrome with chronic respiratory failure.

Rigid spine syndrome (RSS) is a rare myopathic ailment characterized by mild axial and proximal muscle weakness. Muscle contraction in these patients causes limitation of neck and trunk flexion, scoliosis, and mild joint deformity. We report the case of a 30-year-old man with RSS who presented with severe restrictive ventilatory defect (forced vital capacity, 1.53 L, 39% of predicted), mild scoliosis (Cobb's angle 12), proximal muscle weakness and stiff back. Creatine phosphokinase was 986 IU/L. Muscle biopsy of the right vastus lateralis revealed increased variation in muscle fiber diameter, proliferation of endomysium, and type I fiber atrophy. Round and whorled fibers indicating myopathic change were found on sections stained with nicotinamide adenine dinucleotide dehydrogenase and succinate dehydrogenase. RSS was diagnosed based on myopathic findings and clinical presentation. Nocturnal chronic respiratory failure and fragmented sleep developed. He was treated with continuous positive airway pressure and had recovered his normal daily activity by 1-year follow-up. We suggest that patients with RSS should be assessed for possible ventilatory failure; treatment with nasal continuous positive airway pressure or bilevel continuous positive airway pressure therapy should be considered.