Paresthesia (peripheral nerve and muscle disease) refers to a burning or prickling sensation that is usually felt in the hands, arms, legs, or feet, but can also occur in other parts of the body. The sensation, which happens without warning, is usually painless and described as tingling or numbness, skin crawling, or itching.
Lets understand the “Diseases of the nerve” first. They are classified as (eg, polyneuropathy), muscle (eg, myopathy), and neuromuscular junction (eg, myasthenia gravis). These diseases may have a patient to report with varying degrees of sensory loss and weakness. However, specific patterns of the sensory and motor disturbance often helps differentiate between these disorders.
Weakness in limbs can arise from dysfunction of nerve at a neuromuscular junction, or any muscle. Weakness is a general feeling that doctors have difficulty in quantifying and pinpoint. Frequently complains often are described as pain and associated weakness with pain. Pain may limit the action and mobility of a joint, and it is not always true that pain will indicate a true neurologic dysfunction. Patients who complain of painless weakness generally have significant abnormalities on examination. Similar to sensory loss, the distribution of weakness is extremely important.
Hence tests such as “Tinel test”, which is conducted by tapping over a nerve to test for reproduction of pain and paresthesia is a common investigational protocol.
The terms “polyneuropathy,” “peripheral neuropathy,” and “neuropathy” are frequently used interchangeably, but are distinct. Polyneuropathy is a specific term that refers to a generalized, relatively homogeneous process affecting many peripheral nerves, with the distal nerves usually affected most prominently. Peripheral neuropathy is a less precise term that is frequently used synonymously with polyneuropathy, but can also refer to any disorder of the peripheral nervous system including radiculopathies and mononeuropathies. Neuropathy, which again is frequently used synonymously with peripheral neuropathy and/or polyneuropathy, can refer even more generally to disorders of the central and peripheral nervous system.
Polyneuropathy has a wide variety of causes. Few common ones include diabetes mellitus, alcohol abuse,and the rare ones have been found due to forms of Charcot-Marie-Tooth (CMT) disease. It often occurs as a side effect of medication or as a manifestation of systemic disease. The rate of progression of the polyneuropathy in conjunction with its character (axonal or demyelinating) and should be treated accordingly.