Nocturnal Leg cramps refer to recurrent painful tightening which usually occurs in the calf muscles in the night and can cause severe insomnia. Because they occur in the night they are called nocturnal leg cramps.
Nocturnal leg cramps are reported by 50 to 60 percent of adults and by approximately 7 percent of children. Leg cramps are more common in females and their occurrence rises with age.
Pathophysiology and Causes of Nocturnal Leg Cramps
The exact mechanism of leg cramps is not known.
It is suggested that lower motor neurons with hyperactive, high-frequency, involuntary nerve discharge are responsible for these cramps. It is also suggested that modern lifestyles now no longer requires repetitive squatting that stretches the leg tendons and muscles which may contribute to the symptoms.
It is also postulated that during sleep the foot is passively in plantar flexion which leads to maximal shortening of the calf muscles, leading to uninhibited nerve stimulation.
Some research has suggested muscle fatigue to be primary cause of leg cramps.
Leg cramps are found more in patients with neural dysfunction such as parkinsonism. Therefore nerve dysfunction or damage has also been suggested as a cause of leg cramps.
Nocturnal leg cramps have not been associated with dehydration or electrolyte disturbances.
Leg cramp have been found not to be related to changes in the levels of creatinine, calcium, magnesium, sodium, potassium, zinc, glucose, alanine transaminase, total bilirubin, or albumin.
Following are the drugs which have been mainly noted to be associated with leg cramps
- Intravenous iron sucrose
- Conjugated estrogens
Several medical conditions are associated with leg cramps are
- Cardiovascular disease
- Peripheral vascular disease
- End-stage renal disease and hemodialysis
- Lumbar canal stenosis
- Neurologic deficit
- Peripheral neuropathy
- Venous insufficiency
Painful cramps in the night are main symptoms. These cramps may be described as a spasm, tightening, twinge, strain, tetany, swelling, or muscle seizure. Some patients may also report limb movements such as plantar flexion of the foot.
These last an average of nine minutes per episode. One episode of occurrence may be may be followed by hours of recurrent episodes and residual pain.
These cramps can cause loss of sleep [insomnia].
Calf muscles are most commonly involved but foot and thigh cramps are also common.
The posterior calf muscles usually are involved, but cramps of the foot and thigh also are common.
Nocturnal occurrence, visible muscle tightening, and sudden, intense pain are typical manifestations.
The history should include medications patient is taking and any other medical condition which may contribute to the causation.
Physical examination is usually normal though a potential underlying medical cause such as peripheral vascular disease may be suggested.
Therefore detailed examination of the patient must be done especially of the legs and feet, palpation of pulses, cardiac evaluation and neural evaluation.
- Exercise-associated muscle cramping
- Hypnic myoclonus
- Myositis, myalgias
- Periodic limb movement disorder
- Peripheral neuropathy
- Restless legs syndrome
There is no investigation specific to nocturnal leg cramps. Blood tests for electrolyte abnormalities, anemia, glucose levels, thyroid function, liver or kidney disease are done to look for causative factor. Vitamin B12 levels are done to find neuropathy.
Treatment of Nocturnal Leg Cramps
There is no effective treatment for leg cramps currently.
Following measures have been suggested
- Passive stretching and deep tissue massage by patient
- For an acute cramps, forceful stretching by dorsiflexing the foot may be helpful.
- Mild exercises before bedtime like treadmill or stationary cycling
- Quinine used in past as an treatment but is no longer recommended due to the potential adverse effects
- No drug can be recommended for routine treatment but benefits have been observed with use of carisoprodol, diltiazem, gabapentin, orphenadrine verapamil, and vitamin B12 complex.
- Leung AK, Wong BE, Chan PY, Cho HY. Nocturnal leg cramps in children: incidence and clinical characteristics. J Natl Med Assoc. 1999;91(6):329–332.
- . Weiner IH, Weiner HL. Nocturnal leg muscle cramps. JAMA. 1980;244(20):2332–2333.
- Schwellnus MP, Nicol J, Laubscher R, Noakes TD. Serum electrolyte concentrations and hydration status are not associated with exercise associated muscle cramping (EAMC) in distance runners. Br J Sports Med. 2004;38(4):488–492.
- Garrison SR, Dormuth CR, Morrow RL, Carney GA, Khan KM. Nocturnal leg cramps and prescription use that precedes them: a sequence symmetry analysis. Arch Intern Med. 2012;172(2):120–126.
- Matsumoto M, Watanabe K, Tsuji T, et al. Nocturnal leg cramps: a common complaint in patients with lumbar spinal canal stenosis. Spine (Phila Pa 1976). 2009;34(5):E189–E194.
- Coppin RJ, Wicke DM, Little PS. Managing nocturnal leg cramps—calf-stretching exercises and cessation of quinine treatment: a factorial randomised controlled trial. Br J Gen Pract. 2005;55(512):186–191.