Severe forward flexion of the trunk in Parkinson's disease: focal myopathy of the paraspinal muscles mimicking camptocormia.

Pronounced forward flexion of the trunk, often termed camptocormia, is a typical symptom of patients with Parkinson's disease. In 4 parkinsonian patients with camptocormia, paraspinal muscles were studied by electromyography (EMG) and axial computerized tomography (CT) or magnetic resonance imaging (MRI) scans and muscle biopsy. EMG of the lumbar and thoracic paravertebral muscles showed abundant fibrillations, positive sharp waves, and bizarre high-frequency discharges. Spinal CT and MRI scans revealed variable degrees of atrophy and fatty replacement of the thoracolumbar paraspinal muscles on both sides. No other signs of neuromuscular disease were found. Biopsy of the paraspinal muscles revealed end-stage myopathy with autophagic vacuoles, chronic inflammatory myopathy, unspecific myopathic changes, or mitochondrial myopathy. In parkinsonian patients with pronounced forward flexion of the trunk, myopathy confined to the erector spinae muscles must be considered.