Spontaneous anterior interosseous nerve syndrome: clinical analysis of eleven surgical cases

Abstract

The aetiology of anterior interosseous nerve (AIN) syndrome and an optimal treatment strategy remain controversial. Eleven patients with spontaneous AIN syndrome, who were treated by surgical exploration, were reviewed at a mean of 32.5 months after the operation. Eight men and three women were included in the study. None of the patients had a history of trauma and there was no evidence of a neuropathy other than AIN syndrome. Six patients showed complete paralysis of the flexor pollicis longus (FPL) and the flexor digitorum profundus of the index finger (FDS1). Five patients had incomplete paralysis, with isolated lesions of the FPL in two and the FDP1 in three. Surgery was performed 7.8 months after the onset of paralysis. The most common structure of nerve compression was a fibrous band of the flexor digitorum sublimis muscle. However, no definitive compression site or anatomic abnormality could be found in four patients. Ten of the 11 patients had recovered muscle strength above grade 4 within 12 months of the operation. Good results were obtained in 10 patients and fair in only one at final assessment. Four patients (one man and three women) raised cosmetic concerns due to excessive scar formation on the upper forearm. Surgical exploration is recommended only in cases where AIN syndrome is apparent, no other neuronal lesions are apparent, and where there was no recovery after 6 months of conservative treatment. Careful preoperative examination is essential to avoid misdiagnosis and inappropriate operation, particularly in cases of incomplete AIN syndrome.

Fascicular constrictions above elbow typify anterior interosseous nerve syndrome

“…as primary or delayed treatment with varying degrees of success. 5,16,[26][27][28][29] The presence of prodromal pain in many AINS patients and the potential for spontaneous symptomatic resolution, however, are more suggestive of an inflammatory and/or ischemic, rather than compressive, etiology. The frequency of fascicular abnormalities of the median nerve proper described in this and other studies provides further evidence for a noncompressive neuropathy.…”

“…AINS has conventionally been considered an idiopathic neuropathy of the forearm and several studies have reported forearm decompression as primary or delayed treatment with varying degrees of success . The presence of prodromal pain in many AINS patients and the potential for spontaneous symptomatic resolution, however, are more suggestive of an inflammatory and/or ischemic, rather than compressive, etiology.…”

Accessory head of the flexor pollicis longus muscle: anatomical study and clinical significance

“…The AHFPL may lead to an entrapment neuropathy of the anterior interosseous nerve (AIN), known as Kiloh-Nevin syndrome or anterior interosseous nerve syndrome (AINS) [5,15,25]. This syndrome is manifested clinically as a weakness in flexion of the interphalangeal joint of the thumb and the distal interphalangeal joints of the index and middle finger [18,23,26]. The present study was conducted to evaluate the prevalence of this accessory muscle in a South American population sample, its morphometry and relationship with the AIN, constituting valuable information for clinical diagnosis and surgical approaches to the forearm.…”

Persistent anterior interosseous nerve palsy following forearm crutch use

“…Although studies using surgical decompression have shown symptomatic relief in a number of cases,2 18 19 other studies using conservative management reported full symptomatic recovery up to 18 months after onset of palsy 2 16. In a retrospective study of 14 patients reported by Ulrich et al ,2 eight patients were managed conservatively with near full recovery in all patients, while six patients were managed surgically after not showing any signs of recovery after 3 months.…”