Evaluating Neurological Symptoms
February 16, 2010
Evaluating Neurological Symptoms
February 16, 2010
In massage therapy, the tendency is to focus on the role of muscles in pain or injury, sometimes to the exclusion of other soft tissues. Nerves are one of these often forgotten tissues, yet they play a critical role in many pain complaints. Neglecting these tissues can lead to inadequate treatment and the development of chronic pain conditions.
With all the work we perform on soft tissues throughout the body, the absence of knowledge of nerve-tissue disorders is serious. Massage can be an exceptional treatment approach for numerous nerve pathologies because soft-tissue therapy can successfully address nerve compression and tension disorders. Effective treatment of these disorders must begin with accurate evaluation of the client's primary problem. When performed effectively, simple manual examination is one of the most effective tools for evaluating nerve system function.
One might be inclined to think evaluation of nerve-tissue disorders should be left to primary care professionals who have access to MRI, EMG and nerve-conduction testing. However, while high-tech diagnostic studies are effective in certain circumstances, they are not always accurate. For example, median nerve compression does not always show up in nerve-conduction tests for carpal tunnel syndrome.1,2 While no single testing method is always correct, manual neurological examination has a high degree of reliability and should always be a part of a comprehensive evaluation.3,4
Structure, Function and Pathology
The motor versus sensory fiber make-up of peripheral nerves is an important characteristic to note when evaluating neurological symptoms. Most major nerve pathologies affect the peripheral nerves. Peripheral nerves have a dorsal root that carries sensory information and a ventral root that carries motor signals (See Figure 1). The nerve roots blend together shortly after leaving the spinal cord, converging to create the major trunks of the peripheral nerves. These nerves then course through the upper and lower extremities as well as other regions of the body. Most peripheral nerves carry both motor and sensory fibers, but a few carry one or the other almost exclusively.
Compression pathologies are the most common type of nerve injury. Compression can occur anywhere along the length of the nerve from the nerve root all the way to the distal end of the nerve. Pressure on a nerve root is called a radiculopathy. Examples include herniated intervertebral discs, spinal tumors, bone spurs and spinal stenosis, which is a narrowing of the intervertebral foramen where the nerve root exits the spine (See Figure 2).
When pressure is applied to a nerve further along its length in the upper or lower extremity, it is called a peripheral neuropathy. Common examples of peripheral neuropathies include carpal tunnel, thoracic outlet and piriformis syndromes. In a peripheral neuropathy, the nerve can be compressed by muscle, fibrous bands, bone, tendon, local inflammation or other factors. Treatment focuses on reducing compression on the affected nerve, so the practitioner must distinguish where that adverse compression is occurring.
Evaluating for the location and type of nerve pathology is necessary for selecting the most appropriate treatment strategies. Evaluation seeks detailed information on the client's symptoms. Acquire as much detailed information from the client as possible through the history and physical evaluation.
Most of the large peripheral nerves carry both motor and sensory fibers, which have different symptom patterns. Consequently, when there is damage to the nerve, there may be motor and sensory symptoms. However, some nerves carry a much larger percentage of either motor or sensory fibers. In these cases, it is more common to see one type of symptom pattern than another.
For example, if the piriformis muscle is entrapping the posterior femoral cutaneous nerve in the gluteal region (See Figure 3), symptoms are most likely to be pain or paresthesia in the posterior thigh because this nerve is predominantly a sensory nerve innervating the posterior thigh. If the piriformis is compressing the superior gluteal nerve, the most common symptom is weakness in the hip abductor muscles because the superior gluteal nerve is mostly a motor nerve supplying the hip abductor muscles.
The most common sensory symptoms from nerve compression are pain, paresthesia (pins and needles), numbness, burning or electrical-type sensations. Sensory symptoms from nerve compression usually are felt distal to the site of compression. There are exceptions to this guideline, but it generally holds true.
The symptom pattern for compression on a nerve root usually is different from compression on a peripheral nerve. This distinction has important ramifications for treatment. When pressure is applied to a nerve root, the symptoms might be felt anywhere within a specific dermatome. A dermatome is an area of skin supplied by a single nerve root. Figure 4 shows the C8 dermatome, which is the area of skin supplied by fibers that originate from the C8 nerve root (between the C7 and T1 vertebrae). Dermatome maps such as the one in Figure 4 are common in anatomy books. However, these are not absolute, nor is every person exactly the same. There can be slight variations in the dermatome due to anatomical anomalies. In some cases, nerve-root compression symptoms are only felt in a portion of the dermatome, which makes it challenging to pinpoint the problem.
The symptom pattern for compression on a peripheral nerve occurs in regions that overlap the dermatome. Each peripheral nerve supplies sensory innervation to a particular area of skin in the extremity; this is called that nerve's cutaneous innervation. For example, the cutaneous innervation of the ulnar nerve is limited to the ulnar side of the hand as shown in Figure 5. Recognition of nerve symptom patterns requires knowledge of each peripheral nerve's cutaneous innervation or each nerve root's dermatome. Clearly there is overlap between the cutaneous innervation of the ulnar nerve in our example and the C8 dermatome. Such overlap makes clinical analysis more challenging. So, how do you figure out where the symptoms are originating?
The best way to determine the site of compression is through accurate assessment. In general though, if symptoms exist throughout a complete dermatome, then you likely have a nerve root issue (radiculopathy). Choosing tests that further evaluate that nerve root would be the next step. If the symptoms are confined to one nerve's cutaneous innervation, then a peripheral neuropathy is likely. However, because nerve-root compression symptoms can occur in only a portion of the dermatome, further testing would be warranted to rule out nerve-root involvement.
For instance, if a client presented symptoms along the medial side of the arm and forearm extending into the hand, involving the C8 dermatome, it would indicate a C8 nerve-root pathology. If the symptoms were felt only on the ulnar side of the hand, the problem would likely be due to pressure somewhere along the ulnar nerve distal to the nerve root. But, due to dermatome and cutaneous innervation overlap, further testing would be warranted. In addition, further testing would be needed to determine the location of that compression along the path of the ulnar nerve. Treatment could then be directed to the most appropriate location.
When evaluating neurological symptoms, do not assume there is always a mechanical compression or tension problem. Numerous systemic disorders such as multiple sclerosis, myasthenia gravis or diabetes can also produce peripheral neurological symptoms, as could myofascial trigger points from distant muscles. These other pathologies should always be considered as a possibility, and referral is suggested.
Nerve pathologies affect motor function when motor-nerve fibers are involved. The most common symptom from motor-nerve compression is weakness or atrophy in the muscle(s) supplied by the affected nerve. Numerous anatomical references show where motor branches depart from major nerve trunks to supply innervation to muscles. As with sensory symptoms, the affected muscles are distal to the site of compression. Consequently, the more distal the compression site, the fewer muscles will be affected. Figure 6 shows a schematic for compression at two different locations along a nerve and how it affects the muscles innervated by that nerve.
Muscle weakness and atrophy are the most apparent symptoms from motor-nerve compression. However, in some cases pathologies develop from altered biomechanical patterns resulting from muscle weakness induced by nerve injury. Most of our movements involve complex coordination patterns of multiple muscles to accomplish a task. Weakness or atrophy from nerve compression in one of these muscles can cause resultant problems that might not seem related.
Here's an example of motor weakness contributing to a different pathology. The long thoracic nerve innervates the serratus anterior muscle, which is crucial for moving the scapula properly during shoulder abduction. Tightness in the scalene muscles can compress the long thoracic nerve and cause weakness in the serratus anterior muscle. Carrying a backpack, book bag or other heavy item with a shoulder strap could also compress this nerve. When the serratus anterior is weak, the coordination of movement between the scapula and humerus in abduction no longer functions properly and can lead to shoulder impingement syndrome. You might not think of nerve compression as a primary cause in this condition, but muscle weakness from nerve compression is at the root of the problem.
More massage therapists today are working in clinical environments and with clients who have a wide variety of pain and injury conditions. It is crucial that practitioners understand how the symptoms of nerve conditions might present. In some cases, the client should be sent to another health professional for further evaluation, especially when the problem is out of the practitioner's scope of practice or experience level. In other situations, massage can be an extremely important part of the treatment process because few other approaches treat the soft tissues with the degree of specificity of massage therapy. In future columns we'll explore treatment strategies that can be used to address various nerve pathologies.
Any practitioner who wants to address the full gamut of soft-tissue disorders is strongly advised to learn more about function and pathology in the nervous system. Understanding nerve structure and function will aid in treating these conditions. Applying quality clinical reasoning and evaluation skills is part of this process and can greatly improve the outcomes for clients.
- Boden SD, Davis DO, Dina TS, et al. Abnormal magnetic-resonance scans of the lumbar spine in asymptomatic subjects. A prospective investigation. J Bone Joint Surg Am 1990;72(3):403-8.
- Borenstein DG, O'Mara JW, Jr., Boden SD, et al. The value of magnetic resonance imaging of the lumbar spine to predict low back pain in asymptomatic subjects: a seven-year follow-up study. J Bone Joint Surg Am 2001;83-A(9):1306-11.
- Jensen MC, Brant-Zawadzki MN, Obuchowski N, et al. Magnetic resonance imaging of the lumbar spine in people without back pain. N Engl J Med 1994;331(2):69-73.
- Schmid AB, Brunner F, Luomajoki H, et al. Reliability of clinical tests to evaluate nerve function and mechanosensitivity of the upper limb peripheral nervous system. BMC Musculoskelet Disord 2009;10:11.