A muscle cramp is a palpable and sometimes visible sustained involuntary contraction of muscle which is accompanied by pain. A cramp is different from muscle ache (myalgia) in which there is no contraction, and from myotonia, spasticity, dystonia and rigidity, which are not painful. A cramp usually is clinically identical to contractures and must be distinguished by EMG. True cramps occur without provocation. If they are exercise induced or with strain, then it is more likely to be spasm associated with situations exceeding the muscle’s level of conditioning.
Onset of cramps is usually sudden and can occur in a one point or at several parts of one muscle. They can occur at rest especially when the muscle is in a contracted position or after triggering movement (either minor or forceful). It is important to try and establish whether it is dependent on or proportional to exercise or if it is spontaneous.
The diagnosis of “ordinary cramps” is most common, occurring in otherwise healthy people. Cramps are differentiated from myotonia, myalgia, dystonia, spasticity or rigidity by careful history and physical examination. However, there is some degree of stiffness and reduced range of motion as a person cannot move the area without eliciting pain.
Cramps may be due to :
- salt depletion or fluid electrolyte imbalance (including uremia, especially while on hemodialysis or diuretics)
- heat exhaustion and heat stroke
- muscle ischemia (claudication)
- tetanus, rhabdomyolysis
- endocrine disorders (hypothyroidism, hyperthyroidism, parathyroid deficiency)
- motor neuron disease.
They also occur in muscle weakened by partial denervation, in cases of previous poliomyelitis, in peripheral neuropathy and in nerve or nerve root irritation. They also occur with several syndromes such as benign fasciculations of muscular cramps of Foley and Denny-Brown.
Certain drugs can cause cramps, Diuretics can cause cramps probably due to potassium loss. Domperidone, salbutamol/terbutaline IV, ace inhibitors, telmisartan, celecoxib, lacidipine, ergot alkaloids and levothyroxine can also be responsible for cramps. Hypocalcemia following thyroid surgery can cause cramps. Benign nocturnal calf muscle cramps are common in elderly.
Metabolic myopathy (like glycogen storage or lipid storage disease) can cause cramping.
Other than electrodiagnostic studies, screening laboratory testing include complete blood count, serum electrolytes (including calcium and magnesium), ESR, thyroid tests and CPK. If exercise-dependent findings are being evaluated, an ischemic exercise test should be performed to screen for glucose metabolism (lactate formation). Muscle or nerve biopsy eventually may be indicated.
Normally cramps are relived by simple relaxation of the muscle involved and by stretching. Cramps of the calf are common and are relieved by stretching of the calf muscle. This is done by bringing the toe towards you when the leg is completely straight. Heat application and massage may help.
Treatment of the underlying cause or disease may necessary in patients with underlying causative factor for cramping. Rehydration along with calcium supplementation may be needed.
Night cramps may respond to passive exercise or quinine bisulfate. This drug is mainly used for malaria but has seen to relive muscle cramps. It has many side effects and must be used carefully.
Topical applications can be used during or after cramps which can help reduce soreness. These substances have a combination of anti-inflammatory, analgesic and vasodilating agents.
Adequate hydration is indicated in people who usually have cramps. Warming up exercise before any vigorous exercise and cooling down exercises afterwards can prevent cramping.