Via practica 10/2007

PERIPHERAL NERVE DISORDERS

Neuropathy is usually short for peripheral nerve disorder, meaning a disease of the peripheral nerve or nerves. The four major forms of nerve damage are polyneuropathy, autonomic neuropathy – visceral neuropathy, mononeuropathy-peripheral nerve palsy, and mononeuritis multiplex. The most common form is peripheral polyneuropathy, which mainly affects the feet and legs are as followed: Diabetic neuropathy, herpes virus infection neuropathies, HIV-AIDS, toxins, alcoholism, chronic trauma (such as repetitive motion disorders – professional – glass cutter neuropathy) or acute trauma (including surgery), various neurotoxins and autoimmune conditions such as celiac disease, which can account for approximately 16 % of small fiber neuropathy cases. Unmyelinated or „small-fiber“ axons are enclosed within invaginations of the Schwann-cell membranes. Myelination increases axonal conduction velocity; unmyelinated C fibers conduct signals at about 1 m/s, whereas thickly myelinated A fibers conduct signále at 40 to 100 m/s. Neuropathic pain is common in cancer as either a direct result of the cancer compression on peripheral nerves or as an immune and endotoxic side effect of neoplastic condition (paraneoplastic neuropathies); there are also polyneuropathies as a side effect of many chemotherapy drugs. In many cases the neuropathy is „idiopathic,“ meaning no cause is found. A form of spinal nerve entrapment called Posterior Rami Syndrome can lead to neuropathic pain (e.g. dolores nocturni in tabes dorsalis cases). Treatment. Opioid analgesics are to be considered only as a tertiary treatment. Topical agents – lidocaine, ketamine, neurontin, 100 mg/g PLO gel including Carpal Tunnel Syndrome, Capsaicin cream can be beneficial in several neurogenic pain disorders, which causes release of the pain neurotransmitter substance, antidepressants, anticonvulsants (CBZ, lacosamide). Reducing the sympathetic nerve activity alpha-blocker clonidine, beta-blockers, calcium channel blockers such as verapamil, NMDA antagonism have also analgesic effects. Several opioids, particularly methadone and dextromethorphan are usefull, transcutaneous electrical nerve stimulation (TENS) reliefs transiently painfull distress, smoking marijuana is beneficial in treating HIV-associated peripheral neuropathy and in panfull conditions of MS patients. Phototherapy devices emit near infrared light typically at a wavelength of 890 nm. This wavelength is believed to stimulate the release of nitric oxide, an endothelium-derived relaxing factor into the bloodstream, thus vasodilating the capilaries and venuoles in the microcirculatory system. Other treatment modalities are: interferential stimulation, acupuncture, meditation, cognitive therapy, and prescribed exercise.

Keywords: mononeuropathy, polyneuropathy, EMG, C-small fibers, autonomic neuropathy.