Doi's sign

Doi's sign is a clinical sign used in the diagnosis of peripheral neuropathy, specifically focusing on the ulnar nerve's functionality. This sign is named after the physician who first described it. The ulnar nerve is one of the three main nerves in the arm, responsible for innervating various muscles in the hand and providing sensation to the skin of the hand. Doi's sign becomes relevant in conditions where the ulnar nerve is compromised, such as in ulnar nerve entrapment or cubital tunnel syndrome.

Presentation

Doi's sign is observed when a patient attempts to make a fist. The sign is considered positive if there is abnormal flexion of the ring and little fingers, indicating weakness or paralysis of the intrinsic muscles of the hand that are innervated by the ulnar nerve. This abnormal flexion is often accompanied by a claw-like deformity of the hand, known as "ulnar claw," due to the imbalance between the flexor and extensor muscles.

Clinical Importance

The presence of Doi's sign is a significant indicator of ulnar nerve dysfunction. Early detection through signs like Doi's can lead to more timely and targeted interventions, potentially preventing further nerve damage and loss of hand function. It is particularly useful in diagnosing conditions like cubital tunnel syndrome, where the ulnar nerve is compressed at the elbow, and in cases of nerve injury following fractures or trauma to the elbow or wrist.

Diagnosis

To assess for Doi's sign, a healthcare provider will perform a physical examination, focusing on the appearance and functionality of the hand when the patient attempts to make a fist. This assessment is often part of a comprehensive evaluation of peripheral nerve function, which may also include:

• Electromyography (EMG) to measure the electrical activity of muscles
• Nerve conduction studies to assess the speed and strength of nerve signals
• Imaging studies, such as MRI or ultrasound, to visualize the nerve and surrounding structures

Treatment

Treatment for a positive Doi's sign focuses on addressing the underlying cause of ulnar nerve dysfunction. Options may include:

• Conservative measures such as physical therapy, splinting, or anti-inflammatory medications
• Surgical intervention to relieve nerve compression, such as ulnar nerve release or transposition in cases of cubital tunnel syndrome

Prevention

Preventative measures for ulnar nerve dysfunction include ergonomic adjustments to reduce strain on the elbow and wrist, proper technique during repetitive activities, and protective gear during activities that pose a risk of trauma to the nerve.

See Also

• Peripheral neuropathy
• Ulnar nerve entrapment
• Cubital tunnel syndrome
• Claw hand