Westphal's sign

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Westphal's sign is a clinical indicator used in neurology to assess the integrity of the nervous system. It is specifically associated with the absence or diminution of the patellar reflex, also known as the knee-jerk reflex. This sign is named after the German neurologist Carl Friedrich Otto Westphal, who first described it.

Clinical Significance

Westphal's sign is an important diagnostic tool in the evaluation of neurological disorders. The absence of the patellar reflex can indicate a lesion or dysfunction in the central nervous system or the peripheral nervous system. It is often observed in conditions such as tabes dorsalis, a form of neurosyphilis, and other diseases affecting the spinal cord.

Mechanism

The patellar reflex is a monosynaptic reflex arc that involves the L2, L3, and L4 segments of the spinal cord. When the patellar tendon is tapped, it stretches the quadriceps femoris muscle, which in turn sends a signal via the femoral nerve to the spinal cord. The response is a contraction of the quadriceps muscle, resulting in the extension of the leg. Westphal's sign indicates a disruption in this reflex arc.

Associated Conditions

Westphal's sign can be observed in various neurological conditions, including:

• Tabes dorsalis
• Diabetic neuropathy
• Guillain-Barré syndrome
• Multiple sclerosis
• Amyotrophic lateral sclerosis

Diagnostic Procedure

To test for Westphal's sign, a clinician will use a reflex hammer to tap the patellar tendon while the patient is seated with their legs dangling. The absence or reduction of the knee-jerk response is noted as a positive Westphal's sign.

History

Carl Friedrich Otto Westphal first described this sign in the late 19th century. His work contributed significantly to the understanding of reflexes and their role in diagnosing neurological conditions.

See Also

• Patellar reflex
• Neurology
• Reflex arc
• Tabes dorsalis
• Carl Friedrich Otto Westphal