Do Patients Present With A Standard Textbook Pattern of Referred Pain While Having A Pinched Nerve?

Dermatomes- look at C4,5 compare below

One of the useful things I learnt while I was still in physiotherapy school, that I am still using daily, are dermatomes. A dermatome is the area of skin that sends signals to the brain through our spinal nerves. These signals help us sense temperature, pressure and pain. 

When a patient comes in to our clinic with radiculopathy, which means a range of symptoms caused by the irritation of a nerve root, we can gauge what levels of the spine are affected, knowing the dermatomes chart. 

These symptoms can include pain, numbness, tingling sensations, sensory changes, loss of strength and even a change in reflexes. These can occur in the cervical (neck), thoracic (upper back) and lumbar (low back) regions. It is often known as a 'pinched nerve'.

C4,5 check with earlier picture

For example, if a patient comes in complaining of pain in the shoulder it may mean that C4,5 may be implicated. This is especially so if treating the shoulder does not make the patient better.

So I was very interested when I read about the following study, where the researchers studied how often patients who had cervical radiculopathy presented with the standard textbook versus non standard patterns.

Only patients with single level cervical radiculopathy operated by six surgeons were included in this study. Their symptoms of radiculopathy were compared to a standard textbook pattern. 

239 patients' records met the inclusion criteria. Their age, weight, BMI, gender and symptom duration were not different between patients with a standard radicular pattern versus those with a non standard pattern.

Picture of referral pattern from article

Overall, 54% (129 patients) fit the standard textbook pattern while 46% (110 patients) differed from the standard pattern. C5-6 and C6-7 were the two most common levels operated on for radicular pain. Non standard patterns of presentation were found in 50.9% (C5-6) and 44.7% (C6-7) of the cases.

Same sided neck pain (81% of patients) was the most common presenting symptom. Shoulder pain was reported in 142 patients (59.4%). 19.2% of the subjects (46 out of 239) had pain/ symptoms at the neck level with no referred pain down the arm. 

When a non standard pattern was encountered, it differed by 1.68 dermatomal levels, either higher or lower.

The authors concluded that observed patterns of cervical radiculopathy in their study only followed the standard textbook pattern in 54% of patients studied. Non standard referral patterns were more common than thought. 

Now, that's a good reminder to doctors, surgeons and physiotherapists (note to self). Patients suspected of referred pain from the neck and back may not always have symptoms that fit the standard textbook pattern.

We need to do our due diligence to ensure each patient get treated appropriately.

Reference 

McAnany SJ, Rhee JM et al (2019). Observed Patterns Of Cervical Radiculopathy: How Often Do They Differ From A standard, "Netter diagram" distribution? Spine. 19(7): 1137-1142. DOI: 10.1016/j.spinee.2018.08.002.