Paresthesia

What does Paresthesia (Tingling and Numbness) mean?

Paresthesia can be defined as an abnormal sensation that appears at the level of the skin, with no obvious physical cause behind its appearance. The word “paresthesia” is borrowed from the Greek language, with “para” standing for “abnormal” and “esthesia” for “feeling”. It should be mentioned that paresthesia can manifest itself in more than just one way, causing a tingling sensation or numbness. Depending on the underlying cause, the abnormal sensation can either be temporary or permanent.

It is also important to make the distinction between the numbness and tingling sensation. When we speak about a patient presenting numbness in a certain territory of the skin, this means that he/she suffers from reduced or complete absence of sensation in that area. On the other hand, the tingling sensation is more often described as the “pins and needles” sensation. Patients experience the tingling sensation in the most diverse manner, some declaring it is similar to insects crawling on their skin, while others associating it with a tickling or prickling sensation.

Whether it presents itself in the form of numbness or tingling, paresthesia can be accompanied by a number of other symptoms. The condition is often found in association with the restless leg syndrome, as well as with the burning sensation. Itchiness, discomfort and even pain can appear along paresthesia, once again depending on the underlying cause. It is also worth mentioning that the sensations included under the general term of paresthesia can appear in any part of the body, including at the level of the trunk, face, limbs or back. The extremities are often affected by paresthesia, with both the fingers and the toes having a multitude of nerve endings that are capable of transmitting such sensations.

When a person suffers from paresthesia, the sensation experience at the level of the skin is sent to the brain for interpretation. The nerves are responsible for taking over the information from the skin and leading it to the brain. In the situation that the paresthesia sensations appear at the level of the trunk, limbs or back of the head, the communication of these sensations is going to be handled by the spinal nerves. On the other hand, the paresthesia sensations that occur at the level of the face, are mediated by the trigeminal nerve (this is the 5th cranial nerve and it arises directly from the brainstem).

Each spinal nerve will reach a portion of the spinal cord, this portion being known as a dermatome (corresponds to a specific territory of the skin). Using the dermatomes and the abnormal sensations that appear at the level of the skin, paresthesia included, the doctor can determine which nerves have been affected. As you have probably understood by now, the peripheral sensory nerves are responsible for carrying the skin sensations to the brain (through the spinal cord or the cranial nerves and the brain stem). You also need to understand that the paresthesia sensation can also be caused by a disruption of these neural pathways (of various causes or disorders).

Paresthesia Symptoms

These are the most common symptoms that are found in association with paresthesia:

• Sudden onset (no previous warning)
• Tingling or numbness sensation
• Increased or decreased sensitivity on the respective territory of the skin (more common, decreased)
• Pain or discomfort in the respective area (aggravated by touch or movement)
• Muscular weakness
• Muscular cramps
• Abnormal reflexes
• Temperature changes at the level of the skin (skin feels warm or cold to the touch)
• The skin turns a pale or intensely red color (suggestive of circulatory changes in the area)
• The area can become inflamed (with rash present)
• Itchiness can be present in rare situation
• When paresthesia is present at the level of the limb, the patient can describe the sensation of the arm or leg having fallen asleep (temporary numbness sensation).

Causes of Paresthesia

These are the most common causes that can lead to the appearance of paresthesia (depending on how long it may last):

Causes of Temporary/transient paresthesia

• Raynaud’s phenomenon – circulatory problems, manifested especially at the level of the extremities and aggravated by extreme, cold temperatures
• Atherosclerosis – this is often seen at the level of the legs, due to the arteries presenting an insufficient amount of blood; one similar situation is encountered in the patients who suffer from Burger disease – in this case, the paresthesia is accompanied by pain at the level of the calves
• Obdormition – in this situation, the paresthesia appears in the form of numbness and it is caused by the prolonged pressure on the nerve; this is often encountered in those who are accustomed to keeping their legs crossed (their legs fall asleep); however, this condition is temporary and the numbness sensation improves once the pressure has been relieved
• Other causes
  • Seizures
  • Ingestion of substances recommended for body-building (such as beta-alanine)
  • Hyperventilation syndrome
  • Anxiety with panic attacks
  • Dehydration (due to reduced water intake)
  • Mini strokes (transient ischemic attacks)
  • Whiplash
  • Cold sores (tingling sensation precedes the appearance of the lesion; these are caused by the infection with the herpes simplex virus)
  • Shingles (tingling sensation at the level of the chest, following the nerve pathways)
  • Orgasm – the tingling sensation appears at the level of the feet after orgasm (temporary reduction of the blood flow at the level of the extremities)

Causes of Chronic/permanent paresthesia

• Weak immune system (HIV/AIDS, other infections, chronic disorders)
• Hereditary disease
  • Ataxia (with telangiectasia)
  • Denny-Brown’s syndrome (nerve root disorder)
  • Porphyria
  • Charcot-Marie-Tooth disorder (leg muscles are affected)
  • Fabry disease
  • Refsum syndrome
• Exposure to radiation
• Treatment for cancer (chemotherapy)
• Poisoning
  • Exposure/ingestion of heavy metals (mercury, arsenic, lead)
  • Nitrous oxide exposure (prolonged/chronic)
  • Carbon monoxide exposure
  • Ciguatera poisoning
• Insect or snake bites (side-effect of the venom)
• Chronic smoking
• Prolonged or excessive alcohol abuse
• Consumption of illegal drugs
• Medication
  • Anticonvulsant drugs
  • Lomotil
  • Amiodarone
  • Colistimethate
  • Digoxin
  • Dimercaprol
  • Mefloquine
  • Riluzole
  • Tetrodotoxin
  • Thallium
  • Topiramate
• Medication withdrawal (SSRI, benzodiazepine)
• Overdosing on medication (lidocaine, vitamin B6)
• Psychological disorders
  • Anxiety
  • Panic attacks
• Psychiatric disorders
  • Psychosis
  • Schizophrenia
• Migraine
• Skin disorders
  • Burn (chemical or thermal)
  • Frostbites
  • Ito syndrome
  • Acrodynia
  • Acroparesthesia
• Cancer
• Nutritional deficiency
  • Vitamin B1 deficiency (beriberi)
  • Vitamin B5 deficiency
  • Vitamin B12 deficiency
• Fibromyalgia
• Skeletal disorders
  • Arthritis
  • Osteomalacia
  • Osteoporosis
• Blood disorders
  • Thrombosis
  • Polycythemia
  • Thrombocytosis
  • Leukemia
• Autoimmune disorders + connective tissue disorders
  • Rheumatoid arthritis
  • Systemic lupus erythematosus
  • Sjögren’s syndrome
  • Pernicious anemia
  • Diabetes
• Infection + post-infection syndromes
  • Herpes (infection with herpes simplex virus)
  • Herpes Zoster (infection with herpes zoster virus)
  • Other infectious conditions (such as arbovirus)
  • Canker sores
  • Lyme disease
  • AIDS/HIV
  • Leprosy
  • Guillain-Barre syndrome
  • Rabies
  • Syphilis
• Metabolic + hormonal disorders
  • Diabetes
  • Hypoglycemia
  • Hypothyroidism
  • Hypoparathyroidism
  • Hyperaldosteronism (Conn syndrome)
  • Menopause
  • Abnormal electrolyte levels (calcium, potassium, sodium)
  • Uremia
  • Porphyria
• Cardiovascular + circulatory disorders
  • Angina pectoris
  • Atherosclerosis
  • Acute arterial occlusion
  • Vasculitis
  • Raynaud’s phenomenon
  • Vertebrobasilar circulatory disorder
• Disorders of the central nervous system + brain + peripheral nerves
  • Stroke
  • Hemorrhage
  • Multiple sclerosis
  • Tumors
  • Encephalitis
  • Meningitis
  • Disc hernia
  • Cervical spondylosis
  • Carpal tunnel syndrome
  • Sciatica
  • Neuralgia
• Other causes
  • Administration of local anesthesia (dental treatments – the problems can be caused by the trauma to the nerve during the administration of the anesthetic or by the resulting hemorrhage)
  • Cerebral amyloid angiopathy
  • Chiari malformation
  • Celiac disease
  • Complex regional pain syndrome (reflex sympathetic dystrophy)
  • Decompression sickness
  • Fluoroquinolone toxicity
  • Chronic inflammatory demyelinating polyneuropathy
  • Menopause
  • Accidental ingestion of pesticides (pyrethrum, pyrethroid)
  • Syringomyelia
  • Hyperkalemia
  • Hypocalcemia
  • Hypermagnesemia
  • Hypomagnesemia.

Diagnosis of the Cause of Paresthesia

These are the most common methods used for the diagnosis of paresthesia:

• Medical history of the patient
  • Frequency and type of paresthesia
  • Pre-existing conditions
  • Other treatments or surgical interventions
  • Family history (which illnesses)
  • History of trauma or physical injury
• Patient evaluation + anamnesis
  • Identification of areas in the body where paresthesia is present (as tingling or numbness)
  • Description of the paresthesia sensation
  • Triggers of the tingling/numbness sensation (heat, stress, food etc.)
  • Symptoms that accompany the paresthesia (inflammation, muscular weakness, cramps etc.)
  • Systemic symptoms (state of general malaise, fever, chills etc.)
  • Occupation (may be useful in identifying whether the paresthesia sensation appears as occupational hazard)
  • Stress or anxiety levels
  • Unhealthy habits (chronic smoking, alcohol abuse, drugs/medication abuse)
  • Neurological examination (identification of signs that might suggest the involvement of the central nervous system)
• Imaging studies
  • X-ray, MRI or CT scan
    • Head and/or vertebral column
    • Chest
    • Abdomen
    • Bones and/or joints
    • The imaging studies are performed with/without contrast
    • They can be useful in ruling out other potential causes of paresthesia (such as the ones involving the central nervous system)
• Laboratory studies
  • • Complete blood count
    • Erythrocyte sedimentation rate
    • Electrolytes levels
    • Protein levels
    • Thyroid hormones levels
    • Presence of heavy metals
    • Identification of drug abuse
    • Antibodies (in case of infection)
• Urine analysis
  • Glucose in the urine
  • Analysis of color and density
  • Sedimentation rate
  • Proteins in the urine
• Tests for muscular disorders
  • Electromyography (EMG)
  • Nerve conduction test (often used for the confirmation of paresthesia)
• Other tests
  • Lumbar puncture
    • Identification/confirmation of diagnosis for disorders of the CNS (multiple sclerosis, meningitis)
  • Vascular ultrasound + cold stimulation test – in case of suspicion for Raynaud’s phenomenon
  • Nerve biopsy – in rare situations, when the diagnosis cannot be confirmed through other means.

Treatment of Paresthesia

As it was mentioned, paresthesia is a symptom and not a condition on its own. This is the reason why the treatment mainly addresses the underlying condition. Once the condition behind the paresthesia has been successfully treated, the tingling or numbness sensation is going to disappear on its own.

These are the general measures that can be taken in order to improve the paresthesia:

• Avoid periods of prolonged sitting (especially with the legs crossed)
• If you do have to sit for prolonged periods of time, make sure that you stretch or massage the legs
• The tingling or numbness sensation can be improved through self-massage – it is recommended that the massage is either performed with aromatic oils or by using specialized ointments (such as capsaicin); this massage can provide temporary relief from the paresthesia sensation
• Anti-inflammatory medication, such as NSAIDs (acetaminophen, ibuprofen) can help with the associated symptoms (pain relief, reduction of inflammation)
• Antidepressant drugs (amitriptyline) – recommended in low doses, so as to help modify the way the body perceives the pain (makes chronic conditions more bearable)
• Opiate medication (codeine) – recommended as symptomatic treatment for the cases that are more severe (risk of addiction)
• Nutritional deficiencies can be corrected with vitamin supplements.
• Immunosuppressants (prednisone)
• Gamma globulin – intravenous administration
• Anticonvulsants (gabapentin, gabitril)
• Antiviral medication – recommended in patients who suffer from paresthesia caused by shingles
• Topical numbing creams (palliative care) – lidocaine or prilocaine creams (only the recommended amount should be applied, otherwise the excess of cream can actually cause paresthesia)
• Baclofen (high dosage) – recommended in patients who suffer from paresthesia caused by stroke; high doses of Baclofen are required to be administered several times per day (temporary relief)
• Cannabis – this is not an approved treatment but it is often used by those who suffer from HIV/AIDS (temporary relief from the experienced symptoms)

Paresthesia Prognosis

Given the fact that paresthesia is not a condition on its own, one cannot talk about prognosis in this case. However, when the paresthesia is caused by a chronic disorder of the central nervous system or a cardiovascular disease, the prognosis is more negative. One always has to look at the underlying condition, in order to talk about the prognosis for the respective patient.