Dermatomes UpperLimb | Peripheral Neurological Examination

Dermatome assessment is an essential part of neurological examination when suspecting radiculopathy as changes in sensation within a specific dermatome may help you identify the pathological disc level.

In the case of the cervical spine, the most common causes of nerve root pathology are herniated discs, which account for about 20-25% of cases, and degenerative disc disease which accounts for 70-75%. While herniated discs also known as soft disc lesions are rather seen in younger patients, degenerative disc disease or hard disc lesions primarily occur in the older population and the highest incidence of cervical nerve root pathology is found on spinal segments C5-6 and C6-7. 

in their systematic review from 2017, Lemeunier et al. report that a complete peripheral neurological examination when suspecting cervical radiculopathy has a sensitivity of 83% and specificity of 28%. The positive and negative likelihood ratios were 1.15 and 0.6 respectively, which is why we attribute this assessment a rather weak clinical value but it is still the best tool we have.

For dermatome assessment of the upper limb, the patient can be in a comfortable recumbent position with the upper extremities exposed. 

Using a brush like the one found in the handle of most reflex hammers stroke the dermatomal regions on both the affected and unaffected limb and ask the patient whether they feel side by side differences. Furthermore, you can brush across dermatomes on the same side and ask the patient whether they feel a difference.

Other parts of the neurological examination of the upper limb are:

• Myotome Testing (Upper Limb)
• Reflex Testing (Upper Limb)

For the lower limb, the neurological examination can be studied here:

• Dermatome Testing (Lower Limb)
• Myotome Testing (Lower Limb)
• Reflex Testing (Lower Limb)

Lemeunier N, da Silva-Oolup S, Chow N, Southerst D, Carroll L, Wong JJ, Shearer H, Mastragostino P, Cox J, Côté E, Murnaghan K. Reliability and validity of clinical tests to assess the anatomical integrity of the cervical spine in adults with neck pain and its associated disorders: Part 1—A systematic review from the Cervical Assessment and Diagnosis Research Evaluation (CADRE) Collaboration. European Spine Journal. 2017 Sep;26(9):2225-41.

Wainner RS, Fritz JM, Irrgang JJ, Boninger ML, Delitto A, Allison S. Reliability and diagnostic accuracy of the clinical examination and patient self-report measures for cervical radiculopathy. Spine. 2003 Jan 1;28(1):52-62.