Underappreciated statin-induced myopathic weakness causes disability

Area of Science:

• Neurology
• Pharmacology
• Rehabilitation Medicine

Background:

• 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) are associated with myopathic syndromes.
• Previous studies have not prospectively assessed muscle strength, leaving the incidence of statin-induced weakness unknown.

Purpose of the Study:

• To investigate the incidence and characteristics of new-onset walking difficulty and proximal muscle weakness in patients initiating statin therapy.
• To determine if statin-induced weakness is reversible upon discontinuation of the medication.

Main Methods:

• A cohort of 18 patients (8 with hemiparetic stroke, 10 with other neurological conditions) presenting with new walking difficulties after starting statins were studied.
• Clinical examination included manual muscle testing to assess proximal limb and neck flexor strength.
• Patients underwent laboratory tests to rule out myositis or other causes of paresis.

Main Results:

• Patients exhibited proximal muscle weakness (graded 4/5) and difficulty walking, despite reporting no myalgias or elevated muscle enzymes.
• Initial resistance exercises did not improve strength or mobility.
• Discontinuation of statin therapy led to full recovery of proximal strength (5/5) and improved walking ability within 3 months.

Conclusions:

• Statin-induced proximal muscle weakness, potentially linked to genetic predisposition, may be an underappreciated reversible cause of disability.
• Serial muscle testing after statin initiation can help identify this reversible condition.