A neuropathy is any condition that affects the normal activity of nerves outside the brain and spinal cord.
Motor nerves are those which transmit messages from the brain, and control movement; when these nerves are affected, they cause weakness, gait dysfunction, muscle cramping and instability. Sensory nerves transmit messages to the brain recording sensations of cold, pain, light touch, deep touch and vibration; The most common symptoms are numbness, burning, tingling, and pain.
What is special about nerves, as opposed to other tissue, is the presence of the myelin sheath, the outer cover which protects and nourishes nerves; and the manner in which it heals. To achieve full recovery a nerve must undergo three main processes: Wallerian degeneration which is the term used to describe the clearing of damaged nerve tissue; nerve regrowth and finally re-innervation of the affected muscle. It is generally accepted that completely crushed or severed nerves will not recover, but that less severe injuries will heal, typically with regrowth of 1 to 2 mm per day. This means that an adult with nerve damage around their knee-cap might require a year to recover, as the nerve goes through the three stages of healing to re-extend back to the foot. Given such a prolonged time to regenerate the nerve, disuse makes a full recovery difficult. Hence the usefulness of physiotherapy to stimulate appropriate function and modalities which can stimulate regrowth and re-innervation.
Low intensity laser is perhaps the most effective of these modalities, because it can speed healing of all tissue, including nerve tissue, by an average 40%. In an earlier blog, the usefulness of low intensity laser with diabetes neuropathy of the feet was presented because it offered a relatively unknown treatment option for that condition. Much more common in a physiotherapy practice is entrapment or compression neuropathies. They are usually the result of repetitive strain injury, the most common of which are:
- Carpal tunnel syndrome – compression of the median nerve at the wrist,
- Cubital tunnel syndrome – compression of the ulnar nerve at the elbow,
- Sciatica – entrapment of the sciatic nerve in the buttock or by the piriformis muscle, and
- Tarsal tunnel syndrome – compression of the tibial nerve in the foot.
Like injury to any other kind of tissue, such as muscle, ligament and bone, injuries to nerves vary from very mild with few symptoms, to severe damage with many and serious symptoms. Most minor injuries heal with minimal intervention, and it is a natural tendency to try to wait out an injury. That’s fine, but be watchful for the symptoms of nerve damage – pain, tingling, numbness, burning sensation, weakness, etc – that persist or worsen. We notice in the clinic that traumatic injuries such as those sustained in an MVA, which are slow to respond to treatment, often present more clearly as neuropathy as time passes.