Muscle cramps

Muscle cramps are mostly benign and self-limited, but may also be indicative of a wide variety of potentially serious systemic disorders.

Idiopathic (ordinary) muscle cramps are common, short-lived, and usually involve the calf muscle and/or foot.

The diagnostic approach for idiopathic muscle cramps is one of exclusion. Cramps due to known pathologies can be ruled out reasonably quickly and easily by medical history and targeted physical examination.

Non-pharmacological therapy forms the cornerstone of management of muscle cramps in the acute phase. Passive and/or active stretching of the affected muscle(s) is by far the most effective and safest therapy for most acute idiopathic muscle cramps.

Data are extremely sparse regarding ongoing prevention of muscle cramps. With the exception of drug therapies targeted at underlying/precipitating conditions, there are no proven, specific, effective, and safe drug therapies for muscle cramps. Quinine is used in some countries for the prevention of idiopathic cramps, but is associated with serious side effects (e.g., cardiac arrhythmias, thrombocytopenia, hepatotoxicity, blindness). Therapeutic trialling of various medications used for symptomatic benefit is a reasonable approach.

A muscle cramp is a sudden, involuntary, painful muscle contraction or spasm, associated with an increase in frequency of motor action potentials.[1]Bradley WG, Daroff RB, Fenichel GM, et al. Neurology in clinical practice. 5th ed. Volumes 1 and 2. Philadelphia, PA: Butterworth-Heinemann-Elsevier; 2008.[2]Katzberg HD. Case studies in management of muscle cramps. Neurol Clin. 2020 Aug;38(3):679-96. http://www.ncbi.nlm.nih.gov/pubmed/32703476?tool=bestpractice.com [3]American Academy of Sleep Medicine. International classification of sleep disorders - third edition, text revision (ICSD-3-TR). Jun ​2023 [internet publication].​​ Idiopathic (ordinary) muscle cramps are common.

About 80% of episodes involve the gastrocnemius, with a mean duration per episode of 8 to 9 minutes in adults and 2 minutes in children.

The focus of this topic is true cramps (motor unit hyperactivity). These are most commonly idiopathic cramps, but can be associated with other conditions.