Traumatic neuropathies: spectrum of imaging findings and postoperative assessment.

Traumatic injury to peripheral nerves is a significant cause of morbidity and disability. Until reinnervation occurs, electrodiagnostic studies cannot differentiate severe axonotmetic lesions (Sunderland class 4) from complete nerve transection or neurotmesis (Sunderland class 5). This limitation is relevant clinically because in cases of neurotmesis an improved outcome may be achieved with an early surgical repair (within 1 week after trauma). High-resolution ultrasound (US) is an efficient modality to visualize injured nerves and is becoming increasingly important among radiologists and surgeons. Magnetic resonance (MR) imaging is complementary to high-resolution US, especially in evaluating deep-seated and proximal nerve segments. This article describes the imaging features of traumatic peripheral nerve lesions. The role of diagnostic imaging in stretching injuries, contusion trauma, penetrating wounds, and after surgery is discussed. A multimodality diagnostic approach including physical examination, electrophysiology, and US and MR imaging allows an accurate evaluation of most peripheral nerves. Imaging assessment of peripheral nerves trauma is useful for the diagnosis, follow-up, and postoperative evaluation.

Peripheral nerves: ultrasound-guided interventional procedures.

Specific ultrasound (US)-guided interventional procedures on peripheral nerves are reviewed in this article including regional anesthesia, biopsy of neural lesions, and some injection therapies. For these procedures, US is the best modality to provide a safe imaging guidance because of its excellent spatial resolution and real-time capabilities. With US guidance, the radiologist can visualize the needle tip continuously and ensure that the needle is placed precisely in the desired location, avoiding the risk of inadvertent nerve damage. Practical tips and tricks for US-guided needle placement, biopsy of neural lesions, and US-guided therapy are reviewed in this article. The use of US-guided injections in specific clinical settings, such as the percutaneous treatment of carpal tunnel syndrome, Morton's and saphenous neuromas, painful stump neuromas, piriformis syndrome, and meralgia paresthetica are also illustrated here. US allows the clinician to inject drugs with little or no patient discomfort.

Muscle variants of the upper and lower limb (with anatomical correlation).

Several accessory muscles in the upper and lower limb have been described in the medical literature. Most are asymptomatic and represent incidental findings at imaging. In some instances, however, these muscles may become clinically relevant producing palpable swelling, entrapment of neurovascular structures, or exercise-related pain. The diagnosis of accessory muscles is based on recognition of their typical location and on cross-sectional imaging features. Familiarity with their most common location and knowledge of the possible clinical syndromes caused by these supernumerary structures may aid in diagnosis and treatment.

Imaging of neuropathies about the ankle and foot.

Neuropathies about the ankle and foot may be the cause of chronic pain and disability. In most cases, these conditions derive from mechanical or dynamic compression of a segment of a nerve within a narrow osteofibrous tunnel, an opening in a fibrous structure, or a passageway close to a ligament or a muscle. Although the evaluation of nerve disorders primarily relies on neurological examination and electrophysiology, diagnostic imaging is currently used as a complement to help define the site and etiology of nerve compression and exclude other disease possibly underlying the patient' symptoms. In this article, a review of the anatomical and pathological features of nerve entrapments in the distal lower extremity is presented on ultrasound and magnetic resonance imaging, according to the nerve involved.

Hip ultrasound.

In newborns, US has an established role in the detection and management of developmental dysplasia of the hip. Later in childhood, when the limping child is a major diagnostic dilemma, US is extremely helpful in the identification of the varied disease processes underlying this condition, as transient synovitis, septic arthritis, Perthes disease and slipped femoral capital epiphysis. In adolescent practicing sporting activities, US is an excellent means to identify apophyseal injures about the pelvic ring, especially when avulsions are undisplaced and difficult-to-see radiographically. Later on, in the adulthood, US is an effective modality to diagnose tendon and muscle injuries about the hip and pelvis, identify effusion or synovitis within the hip joint or its adjacent bursae and guide the treatment of these findings. The aim of this article is to provide a comprehensive review of the most common pathologic conditions about the hip, in which the contribution of US is relevant for the diagnostic work-up.