Peripheral Neuropathy
Peripheral Neuropathy (PN) is the term that is used to describe damage to the nerves of the peripheral nervous system (nerves outside the spinal cord and the brain). For example, the nerves extending to the arms and legs are considered peripheral nerves. Damage to these nerves can come from direct trauma, or from a side effect of a disease like diabetes.
Causes of Peripheral Neuropathy
- Most common case is called metabolic neuropathy, like diabetes, where high sugar levels injure the nerves. (diabetic neuropathy) Twenty-five percent of Americans are either pre-diabetic or diabetic, so the problem is potentially large.
- Physical trauma: compression, crushing, cutting, projectile injuries. Carpal Tunnel Syndrome (focal entrapment neuropathies) one nerve is trapped in the wrist.
- Toxic Causes: Alcoholism and Chemotherapy (vincristine and the like)
- Others: shingles, malignant disease and radiation
Usual presentation of Peripheral neuropathy (PN)
Signs and symptoms
Sensory function change can occur where the patient can experience numbness, tremors, and gait (walking) imbalance. Other changes that may occur in sensation are: tingling, pain, itching, crawling, and pins and needles. The skin can also be hypersensitive. These patients are unable to tolerate anything touching the extremity that is affected with PN.
Motor symptoms can present as: tiredness, heaviness, gait abnormalities, cramps or tremors.
Treatments
First line of treatment is drugs that are used to treat nerve pain. For example, antidepressants and antiepileptic drugs have been found to be useful in managing nerve pain (neuropathic pain). Commonly used treatments include using a Tricyclic Antidepressant (such as amitriptyline) and antiepileptic therapies such as Gabapentin. These medications have the advantage of efficacy and in many cases they are relatively inexpensive. Lyrica (Pregabalin) is a new anticonvulsant drug used for neuropathic pain. It was designed as a more potent and effect alternative to Gabapentin but is more expensive. If pharmaceutical approaches fail, more aggressive approaches are used. Other therapeutic strategies like topical creams, sympathetic nerve blocks, sympathetic catheter infusions, physical therapy are frequently ineffective.
Dorsal Column Stimulators (DCS) or pacemakers for the spine have been used since the 1960’s for leg pain. This approach is very effective for pain and sensory changes with PN. One recent study with DCS has demonstrated significant effect in diabetic neuropathy. DCS has taken away the pain and also improved sensation based on a study by Dr. McDonnell. 85% of patients undergoing the treatment experienced sensory improvement. In an average of 16 months follow up after implantation of the spinal cord stimulator, the average reduction in visual analog scale pain score was 7.6 points, falling from 9.2 to 1.6.*
10 is maximal pain and 0 is no pain scale.
* Dr. McDonnell reported at the 2009 annual meeting of the American Society of Regional Anesthesia and Pain Medicine (abstract A77)
DCS has been shown to increase circulation and may have help wounds heal