Imaging plays a pivotal role in diagnosing the different types of TOS by visually presenting the various structures involved to delineating the prevalence of anatomical abnormalities, vascular obstructions, or nerve compressions. Imaging is utilised in conjunction with presenting history and physical examination to rule TOS in as a diagnosis. On the contrary, imaging can be beneficial to rule out differential diagnoses that are commonly misconstrued as TOS (Raptis et al., 2016). The types of imaging required are dependent on whether nTOS, vTOS or aTOS is suspected.

X-rays are utilised for nTOS to detect bony abnormalities, including a cervical rib or elongated C7 transverse process that may be constricting the thoracic space. X-rays also check for degenerative changes or fractures in the clavicle that may also contribute to brachial plexus compression (Aralasmak et al., 2012).

sMRIs sufficiently illustrate soft tissues, therefore enabling the evaluation of the scalene and pec minor muscles to detect fibrous bands or muscle hypertrophy (Szaro et al., 2023). However, literature depicts that a specialised form of MRI, called MR Neurography should be used in conjunction with MRIs, as they are designed to visualise peripheral nerves and the surrounding structures. MR Neurography is useful for identifying nerve irritation or compression as identified in nTOS (Magill et al., 2015).

If true nTOS is suspected, nerve conduction studies and electromyography (EMG) are utilised to identify objective nerve dysfunction and signs of denervation in the innervated muscles in the C5-T1 spinal nerve roots (Daley et al., 2022).

Panel A identifies the presence of fibrous bands causing a curve in the C8 nerve root leading to compression at the brachial plexus. (Depicted via the arrow) Identified via a T1-weighted MR neurogram.

Panel B exhibits narrowing at the costoclavicular space as a result of that same fibrous band (identified via the arrow)

Panel C depicts an enlarged C-7 transverse process overlying the C-8 nerve root causing compression in the thoracic outlet (identified via the arrow)

Panel D identifies straightening of C-8 nerve root (identified via the arrow) following surgical removal of the fibrous band decreasing compression at the thoracic outlet.

(Magill et al., 2015)

Panels A and B depict nerve conduction of muscles innervated by the lower trunk of the brachial plexus along the distribution of the ulnar nerve. The reduction of amplitudes and prolonged latencies depicted in these panels are indicators of true nTOS.

Panels C and D Identify relatively normal nerve conduction results, identified via the shorter latency and higher amplitudes indicating control measurements from unaltered nerves.

(Lee et al., 2011).