A standardized ultrasound approach in neuralgic amyotrophy

Abstract

Neuralgic amyotrophy (NA), also referred to as idiopathic brachial plexitis and Parsonage‐Turner syndrome, is a peripheral nerve disorder characterized by acute severe shoulder pain followed by progressive upper limb weakness and muscle atrophy. While NA is incompletely understood and often difficult to diagnose, early recognition may prevent unnecessary tests and interventions and, in some situations, allow for prompt treatment, which can potentially minimize adverse long‐term sequalae. High‐resolution ultrasound (HRUS) has become a valuable tool in the diagnosis and evaluation of NA. Pathologic HRUS findings can be grouped into four categories: nerve swelling, swelling with incomplete constriction, swelling with complete constriction, and fascicular entwinement, which may represent a continuum of pathologic processes. Certain ultrasound findings may help predict the likelihood of spontaneous recovery with conservative management versus the need for surgical intervention. We recommend relying heavily on history and physical examination to determine which nerves are clinically affected and should therefore be assessed by HRUS. The nerves most frequently affected by NA are the suprascapular, long thoracic, median and anterior interosseous nerve (AIN) branch, radial and posterior interosseous nerve (PIN) branch, axillary, spinal accessory, and musculocutaneous. When distal upper limb nerves are affected (AIN, PIN, superficial radial nerve), the lesion is almost always located in their respective fascicles within the parent nerve, proximal to its branching point. The purpose of this review is to describe a reproducible, standardized, ultrasonographic approach for evaluating suspected NA, and to share reliable techniques and clinical considerations when imaging commonly affected nerves.

Neuralgic amyotrophy with multiple hourglass-like constrictions of anterior interosseous nerve: a case report

“…High-resolution peripheral nerve imaging such as MRI and ultrasound technology are considered valuable tools for the diagnosis of neuralgic amyotrophy based on the pathologic basis of HLC ( 2 , 12 , 13 ). Arányi et al reported abnormal ultrasound findings in 74% of neuralgic amyotrophy patients and classified abnormalities as swelling without constriction, swelling with incomplete constriction, swelling with complete constriction, and fascicular entwinement ( 14 , 15 ).…”

Increased 18 F-FDG uptake in denervated muscles in a case of Parsonage-Turner syndrome

“…Although we did not perform HRUG in our patient, it is worth noting that HRUG can be a valuable tool in assessing PTS. Nerve swelling is the most common sonographic finding in PTS, other pathologic HRUS findings that are also observed in PTS include nerve constriction (incomplete or complete) and fascicular entwinement [ 8 ]. HRUG is readily available, lacks contraindications, and has shown good diagnostic utility when performed by experienced examiners.…”

Electrodiagnostic studies and new diagnostic modalities for evaluation of peripheral nerve disorders

“…NA patients show MR and ultrasound imaging abnormalities, such as focal nerve thickening and hourglass constrictions representing inflammatory nerve lesions, within hours to days of onset 124 . Early studies have identified these changes in 75%–90% of cases, 125–128 although it is likely that a lower prevalence of imaging abnormalities will be demonstrated in a broader cross‐section of NA presentations, including milder or atypical cases. Patients with focal nerve constrictions and nerve torsion could benefit from surgical treatment if there is little or no spontaneous recovery 129,130 .…”