Paresthesia

Paresthesia ( or ), spelled "paraesthesia" in British English, is a of tingling, pricking, or numbness of a person's skin with no apparent long-term physical effect. It is more generally known as the feeling of "pins and needles" or of a limb "falling asleep". The manifestation of paresthesia may be transient or chronic.

Etymology

Cause

Transient

Other common examples occur when sustained pressure has been applied over a nerve, inhibiting/stimulating its function. Removing the pressure will typically result in gradual relief of these paresthesias, often described as a "pins and needles" feeling.

Chronic

In older individuals, paresthesia is often the result of poor circulation in the limbs (such as in peripheral vascular disease, also referred to by physicians as PVD or PAD), most often caused by atherosclerosis, the build up of plaque within artery walls, over decades, with eventual plaque ruptures, internal clots over the ruptures and subsequent clot healing but leaving behind narrowing of the artery openings or closure, both locally and in downstream smaller branches. Without a proper supply of blood and nutrients, nerve cells can no longer adequately send signals to the brain. Because of this, paresthesia can also be a symptom of vitamin deficiency and malnutrition, as well as metabolic disorders like diabetes, hypothyroidism, and hypoparathyroidism.

Irritation to the nerve can also come from inflammation to the tissue. Joint conditions such as rheumatoid arthritis, psoriatic arthritis and carpal tunnel syndrome are common sources of paresthesia. Nerves below the head may be compressed where chronic neck and spine problems exist and can be caused by, amongst other things, muscle cramps which may be a result of clinical anxiety or excessive mental stress, bone disease, poor posture, unsafe heavy-lifting practices or physical trauma such as whiplash. Paresthesia can also be caused simply by putting pressure on a nerve by applying weight (or pressure) to the limb for extended periods of time.

Another cause of paresthesia, however, may be direct damage to the nerves themselves, i.e., neuropathy, which itself can stem from injury or infection such as frostbite or Lyme disease, or which may be indicative of a current neurological disorder. Benzodiazepine withdrawal may also cause it as the drug removal leaves the GABA receptors stripped bare and possibly malformed. Chronic paresthesia can sometimes be symptomatic of serious conditions, such as a transient ischemic attack, motor neuron disease, or autoimmune diseases like multiple sclerosis or lupus erythematosus.

The herpes zoster virus (shingles) can attack nerves causing numbness instead of pain commonly associated with shingles. A diagnostic evaluation by a medical doctor is necessary to rule these out.

Demyelinating diseases may also cause cross-talk between adjacent axons and lead to parasthesia. During impulse conduction some aberrant current that escaped a demyelinated axon can circulate in the exterior and depolarize an adjacent demyelinated, hyperexcitable axon. This can generate impulses conducted in both directions along this axon since no part of the axon is in a refractory state. This becomes very serious in conditions such as multiple sclerosis and Guillain–Barré syndrome.

Acroparesthesia

Other

Diagnostic approach

Treatment

In addition to treatment of the underlying disorder, palliative care can include the use of topical numbing creams, such as lidocaine or prilocaine. Care must be take to apply only the necessary amount, as excess can contribute to the condition. Otherwise, these products offer extremely effective, but short-lasting, relief from the condition.

In some cases, rocking the head from side to side will painlessly remove the "pins and needles" sensation in less than a minute. A tingly hand or arm is often the result of compression in the bundle of nerves in the neck. Loosening the neck muscles releases the pressure. Compressed nerves lower in the body govern the feet, and standing up and walking around will typically relieve the sensation. An arm that has "fallen asleep" may also be "awoken" more quickly by clenching and unclenching the fist several times; the muscle movement increases blood flow and helps the limb return to normal. However, in some cases this clenching action simply exacerbates the discomfort. More rapid relief can sometimes be obtained by gently and systematically massaging the affected area of the body.

Manipulation of the neck may aid facial paresthesia, as the trigeminal nerve which innervates the face originates in the upper portion of the spinal cord. Manipulation can also be particularly beneficial when paresthesia is present in the upper or lower extremities. Manipulation should only be carried out by an appropriately qualified chiropractor, osteopath, physical therapist or physician specifically skilled to do so.

Paresthesia caused by shingles is treated with appropriate antiviral medication.

References

External links

Category:Neurology Category:Symptoms and signs: Skin and subcutaneous tissue