Anterior interosseous syndrome

Anterior interosseous syndrome
Synonyms	Kiloh-Nevin syndrome
Pronounce	N/A
Specialty	N/A
Symptoms	Weakness of the thumb, index finger, and middle finger; difficulty with pinch grip
Complications	Muscle atrophy
Onset	Sudden or gradual
Duration	Variable
Types	N/A
Causes	Nerve compression, trauma, inflammation
Risks	Repetitive strain, injury
Diagnosis	Clinical examination, nerve conduction study, electromyography
Differential diagnosis	Carpal tunnel syndrome, pronator teres syndrome
Prevention	N/A
Treatment	Physical therapy, splinting, surgery
Medication	N/A
Prognosis	Good with treatment
Frequency	Rare
Deaths	N/A

A neuropathy affecting the anterior interosseous nerve

Anterior interosseous syndrome (AIS) is a medical condition characterized by the impairment of the anterior interosseous nerve, a branch of the median nerve. This condition results in weakness of the muscles innervated by this nerve, leading to specific functional deficits in the hand and forearm.

Anatomy

The anterior interosseous nerve is a motor branch of the median nerve that originates in the forearm. It supplies the flexor pollicis longus, the lateral half of the flexor digitorum profundus, and the pronator quadratus. These muscles are responsible for flexion of the thumb and index finger, as well as pronation of the forearm.

Causes

Anterior interosseous syndrome can be caused by various factors, including:

• Trauma: Direct injury to the forearm can damage the anterior interosseous nerve.
• Compression: The nerve may be compressed by anatomical structures such as the pronator teres muscle or fibrous bands.
• Inflammation: Conditions such as neuritis can lead to inflammation and subsequent dysfunction of the nerve.
• Iatrogenic: Surgical procedures in the forearm region may inadvertently affect the nerve.

Symptoms

The primary symptoms of anterior interosseous syndrome include:

• Weakness in the flexor pollicis longus and the lateral half of the flexor digitorum profundus, leading to difficulty in flexing the thumb and index finger.
• Inability to perform the "pinch grip" between the thumb and index finger.
• Weakness in the pronator quadratus, affecting forearm pronation.
• Absence of sensory loss, as the anterior interosseous nerve is purely motor.

Diagnosis

Diagnosis of anterior interosseous syndrome is primarily clinical, based on the characteristic motor deficits. Electromyography (EMG) and nerve conduction studies can be used to confirm the diagnosis and assess the extent of nerve involvement. Imaging studies such as MRI may be employed to identify any compressive lesions.

Treatment

Treatment options for anterior interosseous syndrome include:

• Conservative management: Rest, splinting, and physical therapy may be effective in mild cases.
• Medications: Nonsteroidal anti-inflammatory drugs (NSAIDs) can help reduce inflammation and pain.
• Surgical intervention: In cases where conservative treatment fails, surgical decompression of the nerve may be necessary.

Prognosis

The prognosis for anterior interosseous syndrome varies depending on the underlying cause and the timeliness of treatment. Early intervention often leads to better outcomes, with many patients experiencing significant improvement in function.

Related pages

• Median nerve
• Peripheral neuropathy
• Nerve compression syndrome