True Neurogenic Thoracic Outlet Syndrome with Elongated C7 Transverse Processes in a Hemiplegic Patient: A Case Report

Thoracic outlet syndrome (TOS) is caused by the compression of neurovascular structures in the thoracic cage. TOS can be classified into neurogenic TOS (NTOS) and vascular TOS. Congenital anomalies, such as cervical ribs and elongated C7 transverse processes, may be the cause of NTOS. NTOS can be subcategorized as either disputed NTOS or true NTOS. True NTOS, a very rare disease with a prevalence of about one in a million, is diagnosed by the weakness and atrophy of T1-innervated intrinsic muscles of the hand and corresponding electrodiagnostic abnormalities. We report a case of a 42-year-old patient, who presented with a 5-year history of clumsiness and 1 1-year history of weakness and atrophy in her right hand. The patient was diagnosed with true NTOS during comprehensive rehabilitation, which she received for left hemiplegia due to intracranial hemorrhage. Elongated bilateral C7 transverse processes were found on a radiological evaluation. True NTOS is often overlooked or mistaken for carpal tunnel syndrome, thus delaying the diagnosis and inevitably worsening outcomes. Therefore, an electrodiagnostic study is crucial for detecting true NTOS, rather than typical physical examinations such as the Roos stress test and Adson’s test.