Paresthesia, is a sensation of tingling, tickling, prickling, pricking, or burning of a person's
skin with no apparent long-term physical effect.
The manifestation of a paresthesia may be transient or chronic.
The most familiar kind of paresthesia is the sensation known as "pins and needles" or of
a limb "falling asleep".
A less well-known but still fairly common paresthesia is formication.
Etymology The word paresthesia comes from the Greek
para and aisthesia.
Cause Transient
Paresthesias of the hands, feet, legs and arms are common, transient symptoms.
The most common, everyday cause is temporary restriction of the blood supply to an area
of nerves, commonly caused by leaning or resting on parts of the body such as the legs, other
causes include conditions such as hyperventilation syndrome and panic attacks.
A cold sore outside the mouth, not a canker sore inside the mouth, can be preceded by
tingling, an interesting observation because a cold sore is caused by HSV.
Viruses are also infamous for causing tingling and shingles on the chest.
Other common examples occur when sustained pressure has been applied over a nerve, inhibiting/stimulating
its function.
Removing the pressure typically results in gradual relief of these paresthesias.
Chronic Chronic paresthesia indicates a problem with
the functioning of neurons or poor circulation.
In older individuals, paresthesia is often the result of poor circulation in the limbs,
most often caused by atherosclerosis, the buildup 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.
It can also be a symptom of mercury poisoning.
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, among other things, muscle cramps that 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 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 may be indicative of a current neurological disorder.
Neuropathy is also a side effect of some chemotherapies.
Benzodiazepine withdrawal may also cause paresthesia 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, or autoimmune diseases like multiple sclerosis or lupus erythematosus.
The herpes zoster disease 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 paresthesia.
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 Acroparesthesia is severe pain in the extremities,
and may be caused by Fabry disease, a type of sphingolipidosis.
It can also be a sign of hypocalcemia.
Dentistry Paresthesia or "persistent anesthesia" is
a transient or potentially permanent condition of extended numbness after administration
of local anesthesia and the injected anesthetic has terminated.
Potential causes include trauma induced to the nerve sheath during administration of
the injection, hemorrhage about the sheath, type of anesthetic used, or administration
of anesthetic potentially contaminated with alcohol or sterilizing solutions.
Other Other causes may include:
Diagnostic approach The nerve conduction study usually provides
useful information for making diagnosis.
A CT scan is sometimes used to rule out some causes from the central nervous system.
Treatment Medications offered can include the immunosuppressant
prednisone, intravenous gamma globulin, anticonvulsants such as gabapentin or Gabitril and antiviral
medication, among others, according to the underlying cause.
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 taken 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.
Paresthesia caused by shingles is treated with appropriate antiviral medication.
References
[Clinical and neurological abnormalities in adult celiac disease, G. Cicarelli • G.
Della Rocca • M. Amboni • C. Ciacci • G. Mazzacca • A. Filla • P. Barone,
Neurol Sci 24:311–317 DOI 10.1007/s10072-003-0181-4] External links
paresthesia at NINDS What makes your arms, legs and feet fall asleep?