Camptocormia, a late complication of statin-associated autoimmune myopathy. (SAM)
Background:
Statins are used widely to lower cholesterol. Reversible myalgia is the most common muscle directed side effect of statins. However, 2-3/100,000 of treated patients develop a progressive autoimmune myopathy, which requires immunosuppression. SAM presents with proximal limb and neck weakness. Truncal weakness can occur but frank camptocormia is rare.
Results:
We report a female patient with a history of statin exposure who presented in 2003 at 57 yo with progressive symmetrical proximal weakness affecting neck and extremities. She exhibited a raised erythematous rash periorbitally and on the neck and shoulders. Creatine phosphokinase (CPK) was 24,450 U/l. Muscle biopsy showed necrosis without significant inflammation. She responded well to IVIg, steroids, and azathioprine, regaining normal strength and ambulation. Treatment was transitioned to low doses of prednisone and infrequent IVIg dosing. Approximately 10 years after initial presentation she experienced increasing difficulty standing up straight, resulting in camptocormia. CPK was again elevated in the 500-1000 range. MRI of the thoracic spine and ultrasound of paraspinal muscles showed fatty replacement of paraspinal muscles. HMG CoA reductase antibody level was elevated. She was treated with infrequent IVIg, and higher doses of prednisone. Rituximab was ineffective. Methotrexate caused transaminitis. IVIg was increased to monthly dosing and CK levels fell to normal. Camptocormia stabilized but did not improve. Limb strength remained relatively normal.
Conclusions:
Camptocormia or bent spine syndrome is a rare manifestation of neurological disease, seen in patients with neuromuscular junction disorders, parkinsonism, and certain myopathic conditions. A recent review found 12/16 patients had prominent axial weakness, one with camptocormia. Our case illustrates that progressive camptocormia can be a late manifestation of partially-treated SAM and can occur in the presence of relatively normal limb strength.