[MRI and leg stump neuroma].

OBJECTIVE: To describe RMI aspects of leg stump neuroma and to evaluate RMI scan interest for neuroma diagnosis and management.

POPULATION AND METHOD: During a 2 years period, 224 amputated patients consulting for pain or prostetics problems were studied. In 10 cases, a characteristic pain leads to neurona diagnosis. This is described as a sensation of ascending or descending electric shock induced by the stimulation of an identified point with a reproducible topography. In all these cases, RMI scans were performed. In thirty two other cases, a RMI scan was performed to confirm a pathology (bursitis, bone abnormality) or in order to establish an etiologic diagnosis. Twelve neuromas were diagnosed.

RESULTS: RMI scan showed a neuroma in the ten cases with a clinical suspicion and two asymptomatic neuromas were diagnosed out of the 32 patients without clinical suspicion. Medium delay between amputation and neuroma diagnosis is 11,6 year. In six cases, staking was modified and in six other cases, surgery was necessary. In aIl cases, clinical manifestations disappeared. Vanous RMI aspects ofneuromas are described and illustrated. Neuroma is observed on the extremity of a nerve that have a wavy aspect on its top. The neuroma is an oblong structure, with clear limits. There is an hyposignal with Ti sequence and variable signal with T2 and after gadolinium injection.

DISCUSSION: RMI scan is a good way to diagnose amputee neuroma. It makes it possible to demonstrate the pathological character of the neuroma. It has to be performed when a neuroma is suspected. It enables to confirm the diagnosis and establish the exact topography and anatomic connection. Mechanical strains role as a factor of discovering the neuroma is discussed because of the concomitant evolution of associated lesions (bursitis, bone edema). Surgical repair takes place after correcting abnormal mechanical strains.