Sensory distribution of CTS
Carpal tunnel syndrome is the compression of the median nerve within the carpal tunnel, causing numbness in the palmer and side of the thumb, index, middle fingers and half of the ring finger. Palm numbness is not considered as a symptom from CTS but median nerve entrapment as the palmer cutaneous branch does not enter the carpal tunnel [1].
Presentations of the motor deficit from CTS
The median nerve innervates the two lumbricals (index and middle), the abductor pollicis brevis, flexor pollicis brevis, opponens pollicis. Therefore, compression of the median nerve within the carpal tunnel manifests the weakness in these muscles [1].
C6-C7 nerve root compression
Motor function
Presentation of C6-C7 nerve root compression will be different from CTS.
C6 nerve root compression may manifest with weakness in the wrist extension, elbow flexion and C7 nerve root compression may present with weakness in the wrist flexion and elbow extension [2].
Sensory distribution
C6 nerve root compression may show numbness or sensory change in the radial side (thumb side) of the forearm, the palm and the dorsum. Also, reflexes of C6 may show no response or weak response [2].
What if the median nerve entrapment occurs somewhere in the forearm or at the elbow?
The median nerve compression occurs at the elbow and the forearm. They are called anterior interosseous nerve syndrome (AINS) and pronator syndrome [3]. Compression of pronator teres with the elbow extension can be helpful to rule in [3].
Positive spurling test and diminished reflexes may be used to rule in cervical radiculopathy [4]. Neurogenic Thoracic Outlet Syndrome (NTOS) may be suspected when symptoms are present in distribution of C5-C7 myotome or dermatome due to compression of the upper plexus. It can also refer to the head, around the scapula or the chest [5].
Thorough history taking/receiving and objective tests help therapists identify what it is.
References
[1] Demircay, E., Civelek, E., Cansever, T., Kabatas, S., & Yilmaz, C. (2011b). Anatomic variations of the median nerve in the carpal tunnel: a brief review of the literature. Turkish Neurosurgery. Published. https://doi.org/10.5137/1019-5149.jtn.3073-10.1
[2] Kirshblum, S. C., Burns, S. P., Biering-Sorensen, F., Donovan, W., Graves, D. E., Jha, A., Johansen, M., Jones, L., Krassioukov, A., Mulcahey, M., Schmidt-Read, M., & Waring, W. (2011). International standards for neurological classification of spinal cord injury (Revised 2011). The Journal of Spinal Cord Medicine, 34(6), 535–546
[3] Bair, M. R., Gross, M. T., Cooke, J. R., & Hill, C. H. (2016). Differential Diagnosis and Intervention of Proximal Median Nerve Entrapment: A Resident’s Case Problem. Journal of Orthopaedic & Sports Physical Therapy, 46(9), 800–808. https://doi.org/10.2519/jospt.2016.6723
[4] Sleijser-Koehorst, M. L., Coppieters, M. W., Epping, R., Rooker, S., Verhagen, A. P., & Scholten-Peeters, G. G. (2021). Diagnostic accuracy of patient interview items and clinical tests for cervical radiculopathy. Physiotherapy, 111, 74–82. https://doi.org/10.1016/j.physio.2020.07.007
[5] Povlsen, S., & Povlsen, B. (2018). Diagnosing Thoracic Outlet Syndrome: Current Approaches and Future Directions. Diagnostics, 8(1), 21. https://doi.org/10.3390/diagnostics8010021
