Clasp-knife response

Clasp-knife response is a medical term used to describe a type of muscle response. It is a characteristic of spasticity in which a muscle initially resists movement, but then gives way. This response is named for its similarity to the action of a clasp-knife, where there is initial resistance when the blade is closed, but then it snaps shut.

Overview

The clasp-knife response is a type of hypertonic reflex that is seen in conditions such as cerebral palsy, stroke, and multiple sclerosis. It is caused by damage to the upper motor neurons that control voluntary muscle movement.

When a muscle with clasp-knife spasticity is passively stretched, there is increased resistance to the stretch at the beginning. However, as the stretch continues, the resistance suddenly decreases, similar to the action of a clasp-knife being closed.

Clinical Significance

The clasp-knife response is a significant clinical finding that can help in the diagnosis of certain neurological conditions. It is often seen in patients with lesions of the pyramidal tract, such as those caused by stroke or multiple sclerosis.

In addition to the clasp-knife response, these patients may also exhibit other signs of upper motor neuron damage, such as hyperreflexia, Babinski sign, and muscle weakness.

Diagnosis

The clasp-knife response is typically identified during a neurological examination. The doctor will passively stretch the patient's muscle to see if there is initial resistance followed by a sudden decrease in resistance.

Treatment

Treatment for conditions that cause the clasp-knife response typically involves managing the underlying condition. This may include physical therapy, occupational therapy, and medication to manage symptoms.

See Also

• Spasticity
• Upper motor neuron
• Cerebral palsy
• Stroke
• Multiple sclerosis

Clasp-knife response Resources
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