Low Back Pain Assessment – 3

Neurological

Often in cases of LBP patients may suffer with referral of symptoms into the lower limbs. A classic is an ache into the buttock regions. Symptoms such as this may be referred directly by structures around the lumbar regions and not be truly neurological per se. Referral of symptoms by a structure into a seemingly unrelated region is common throughout the body, and while the theory of segmentalism may be questioned in contemporary research, the fact that many structures share the same nerve roots remains true. Therefore an injury to one structure may lead to symptoms being referred into other areas and structures that share the same nerve root. This is not however a true neurological symptom. A neurological symptom occurs when we see a true loss of sensation or power, and/or a change in the activity of action potentials within nerves, seen as reflexes.

Sensation is tested using cotton wool, comparing each limb at the same point. If cotton wool is not seen as sensitive enough then sharp and blunt appreciation may be used, or even more accurately the ability to detect extremely light touch using von Frey filaments. Strength is ascertained by simple active resistance by the therapist, but could be more accurately measured using a dynamometer. Reflexes are tested using a patella hammer with the therapist looking for signs of increased or decreased activity within the nerves. Increased briskness of reflexes may alert the therapist to more central changes making testing for upper motor neuron lesions essential. One way of testing this is with the Babinski test. Decreased reflexes may be more indicative of peripheral lesions.

On top of this there may be direct aggravation of a nerve which will lead to a decrease in its ability to glide normally. A straight-leg-raise (SLR) or slump test will alert the therapist to this problem. The most common symptom seen in these patients is Sciatica, where the sciatic nerve is aggravated either by a peripheral lesion or a nerve root impingement.

Current knowledge of pain science points towards changes in cortical processing within higher centres in response to prolonged pain. A potential way of treating this is through use of 2-point discrimination (Wand et al 2010). It would therefore be reasonable to suggest that 2-point discrimination may be used as a tool to assess the changes in cortical function. 2-point discrimination is a test of sensory accuracy that may be performed at any site in the body. An inability to differentiate two points of pressure, outside normative data for that body region may suggest cortical misrepresentation.

References:

Ferreira M L, Ferreira P H, Latimer J, Herbert R D, Maher C, Refshauge K. Relationship between spinal stiffness and outcome in patients with chronic low back pain. Manual Therapy 2009: 14;61-67

O’Sullivcan P. Diagnosis and classification of chronic low back pain disorders: Maladaptive movement and motor control impairments as underlying mechanism. Manual Therapy 2005: 10;242-255

Wand B M, Parkitny L, O’Connell N E, Luomajoki H, McAuley J H, Thacker M, Moseley L. Cortical changes in chronic low back pain: Current state of the art and implications for clinical practice. Manual Therapy 2011: 16(1);15-20