Paresthesia is the tingling sensation that we experience in certain regions of our body when a nerve is pinched or compressed. It is common for it to appear in the extremities, especially in the hands and feet. It is completely painless but it can be an awkward sensation, similar to feeling hundreds of tiny cold-water droplets falling on the skin while also sensing numbness. It is transitional, however, in some cases it can be difficult to bear.
“Sensations from various parts of the body are taken by the peripheral sensory nerves to the spinal cord. From spinal cord, the signals reach the brain with the help of the trigeminal nerve and brain stem. Hence, any problem in this pathway may result in paresthesia. Paresthesia is an abnormal condition which causes an individual to feel a sensation of burning, numbness, tingling, itching or prickling. It frequently happens in the extremities, but it can occur in other parts of the body as well.”1
“Paresthesia is a variety of neuropathic pain arises as a spontaneous and abnormal sensation. The problem may arise from an abnormality anywhere along the sensory pathway from the peripheral nerves to the sensory cortex. Paresthesia are often described as pins-and-needle sensation. Particular kinds of paresthesias can be seen in the central nervous system (CNS) as follows: focal sensory seizures with cortical lesions, spontaneous pain in the thalamic syndrome, or bursts of paresthesia down the back or into the arms upon flexing the neck (Lhermitte’s sign) in patients with multiple sclerosis (MS) or other disorders of the cervical spinal cord. Level lesions of the spinal cord may cause either a band sensation or a girdle sensation, a vague sense of awareness of altered sensation encircling the abdomen. Nerve root lesions or isolated peripheral nerve lesions may also cause paresthesia, but the most intense and annoying paresthesia is due to a multiple symmetric peripheral neuropathy (polyneuropathy).”2
After a few minutes, control over the affected area is regained and the individual returns to normal. In other cases, paresthesia has a longer duration and may even cause pain.
Incidence of Paresthesia
“Paresthetic non-painful tingling has been reported in patients suffering from disorders of peripheral nerves, dorsal roots, and the dorsal column of the spinal cord, and was related to spontaneous aberrant bursting activity of large myelinated sensory neurons from the skin. […] Tingling sensations can be induced by a variety of mechanical stimulations. When body weight rests on a body part for too long, the total blood flow is usually not decreased significantly; however, the local supply of nutrients and oxygen for the sensory nerves becomes insufficient, which causes ectopic neuronal activity responsible for tingling. Tingling as a result of altered nerve function is also frequently observed, for example, when a nerve is chemically anesthetized. Tingling can also be induced by electrical nerve stimulation in a frequency-dependent manner; lower stimulation frequencies were perceived as small pricks, while higher frequencies cause non-painful tingling. The increasing intensity of dermal electrical stimulation evokes three different sensations with consecutive sensory thresholds: tactile sensation, tingling, and pain.”3
“Paraesthesia can occur due to diseases and conditions affecting the peripheral nervous system such as nerve injury from trauma, osteomyelitis, polyneuropathy as in diabetes mellitus and infections such as shingles. It may also originate from the central nervous system as seen in disorders such as stroke, multiple sclerosis and migraine. Paraesthesia in the face, particularly in the lower jaw, may result from dental causes. Mental and inferior alveolar nerve paraesthesia is an uncommon complication which can be associated with endodontic treatment. Careful consideration of all the possible causes is necessary for accurate diagnosis, management and prevention.”4
Factors related to Paresthesia
There are numerous factors that influence the appearance of paresthesia. Some of them are:
- Poisoning: Usually related to heavy metals or arsenic poisoning. “Arsenic toxicity studies from China typically focus on symptoms of neurotoxicity, including loss of hearing, loss of taste, blurred vision, and tingling/numbness in the limbs. Altered mental health is comorbid with these ailments, including a prevalence of insomnia, anxiety and depression, and symptoms of distress”5
- Diabetes: Blood glucose levels are elevated because the amount of insulin is insufficient or the cells are resistant to the action of it. Any alteration in the endocrine pancreas, which is responsible for synthesizing insulin, involves alterations in the control of blood glucose. “The most common neuropathy affecting individuals with diabetes is diffuse somatic neuropathy of the distal symmetric sensorimotor type. Patients most often have a mixed sensorimotor defect and may experience pain, paresthesia, hyperesthesia, dysesthesia, proprioreceptive defect, loss of sensation, and muscle weakness and atrophy. Autonomic nerve function is often impaired and occasionally a particular nerve fiber is predominantly affected. Small nerve fiber injury leads to painful neuropathy with preservation of large myelinated fiber function. Deep tendon reflexes, vibration sense threshold, and proprioreception are preserved. Neuropathy affecting predominantly the large nerve fibers leads to motor and proprioreceptive dysfunction. This form of neuropathy resembles the neuropathy seen in tabes dorsalis and is termed ‘pseudotabes’ form of diabetic neuropathy.”6
- Deficit of some nutrients: In most cases the cause is vitamin B12 deficiency but dehydration can also play a part. Dizziness and a feeling of weakness are frequent. “Although considered an “old” disease, new information is constantly accruing about B12 deficiency, the broad array of its effects, and methods for its diagnosis. B12deficiency primarily affects the hematopoietic system, but its effects extend to other tissues and organs, most notably the nervous system. The spectrum of clinical presentations is broad so that diagnosis depends first on a high index of suspicion and then on the judicious application of appropriate testing. Because B12 deficiency is amenable to simple replacement therapy, diagnosis is critical. Several questions still remain unanswered concerning B12 deficiency, including the possible harmful effects of high folate levels in subjects with low B12 status, particularly with respect to neurological damage. Other newer areas of investigation that may provide better insights into the variability of expression of B12 deficiency include genetic analysis and the effects of the microbiome.”7
- Alterations of thyroid functioning: Specifically, hyperthyroidism. In this pathology, there is an increase in the production of thyroid hormones. The results are typical manifestations of an accelerated metabolism, such as tremors or tachycardia. “Severe paresthesia of glove-and-stocking type distribution suggests an involvement of peripheral sensory nerves. Since this symptom occurred during the same period of the development of subacute thyroiditis and disappeared during recovery from subacute thyroiditis, we propose that the cause of paresthesia is likely due to the subacute thyroiditis. The differential diagnosis of unexplained paresthesia may need to include subacute thyroiditis especially in those patients with thyroid gland tenderness and an increased erythrocyte sedimentation rate.”8
- Unhealthy habits: Most notably, smoking, alcoholism and the consumption of drugs or other toxic substances.
- Diseases of autoimmune character: Some examples are rheumatoid arthritis and lupus erythematosus. During arthritis the joints are inflamed, producing intense. In the case of lupus, the immune system damages the organism systemically.
- Multiple sclerosis: It is a progressive neurological disease, affecting several regions of the body. This situation makes speech and locomotion difficult. “MS is a chronic neurological disease often interfering with life and career plans of an individual . MS is categorized into 4 distinct types, primarily based on its clinical course, which are characterized by increasing severity: (a) Relapsing/remitting MS (RRMS), the most common form, affecting 85% of all MS patients which involves relapses followed by remission; (b) secondary progressive MS (SPMS), which develops over time following diagnosis of RRMS; (c) primary progressive MS (PPMS) affecting 8–10% of patients, noted as gradual continuous neurologic deterioration; and (d) progressive relapsing MS (PRMS) the least common form (<5%), which is similar to PPMS but with overlapping relapses. MS leads to a wide range of symptoms with various severity involving different parts of the body. MS diagnosis is mainly clinically based however, magnetic resonance imaging (MRI) assists in diagnosis. As such, examination of the cerebrospinal fluid (CSF) and visual induced potentials with MRI can assist in confirming the clinical suspicion of MS. MS symptoms and disease progression are varied, with some individuals experiencing little disability while most (up to 60%) require a wheelchair 20 years from diagnosis><5%), which is similar to PPMS but with overlapping relapses. MS leads to a wide range of symptoms with various severity involving different parts of the body. MS diagnosis is mainly clinically based however, magnetic resonance imaging (MRI) assists in diagnosis. As such, examination of the cerebrospinal fluid (CSF) and visual induced potentials with MRI can assist in confirming the clinical suspicion of MS. MS symptoms and disease progression are varied, with some individuals experiencing little disability while most (up to 60%) require a wheelchair 20 years from diagnosis”9
- Encephalitis: Inflammation of the encephalon, the cerebellum and the medulla. Usually, the cause is infectious and requires urgent treatment.
- Presence of a tumor: in areas within the central nervous system (CNS).
- Transient Ischemic Attack (TIA): For a small period of time, the blood supply to the brain is interrupted. The symptoms disappear after a few days if the patient is treated in time but it can cause irreversible damage to the CNS. “TIAs are brief episodes of neurological dysfunction resulting from focal cerebral ischemia not associated with permanent cerebral infarction. In the past, TIAs were operationally defined as any focal cerebral ischemic event with symptoms lasting 24 hours. Recently, however, studies from many groups worldwide have demonstrated that this arbitrary time threshold was too broad because 30% to 50% of classically defined TIAs show brain injury on diffusion-weighted magnetic resonance (MR) imaging (MRI).”10
- Other pathologies related to the CNS: We can mention carpal tunnel syndrome, in which there is excessive pressure on the carpal nerve located in the forearm. Therefore, it causes weakness of the hand and the feeling of paresthesia. “In patients with carpal tunnel syndrome, pain and paresthesias may radiate to the forearm, elbow, and shoulder. Decreased grip strength may result in loss of dexterity, and thenar muscle atrophy may develop if the syndrome is severe. Although one hand typically has more severe symptoms, both hands often are affected. Nonspecific flexor tenosynovitis is the most common cause of carpal tunnel syndrome. However, many conditions, including aberrant anatomy, infections, inflammatory diseases, and metabolic disorders, can cause or exacerbate the syndrome.”11
- Certain pathologies at the cardiovascular level: If pressure of the vessels increase in certain regions of the brain, irreversible damage can be caused.
Oral and Dental Paresthesias
“Dental paresthesia is loss of sensation caused by maxillary or mandibular anesthetic administration before dental treatment. This review examines inferior alveolar block paresthesia symptoms, side effect and complications. Understanding the anatomy of the pterygomandibular fossa will help in understanding the nature and causes of the dental paresthesia. In this review, we review the anatomy of the region surrounding inferior alveolar injections, anesthetic agents and also will look also into the histology and injury process of the inferior alveolar nerve.”12
“Oral paresthesias are common in clinical practice but they often go unnoticed and untreated. Psychogenic oral paresthesia is an unpleasant sensation of tingling or pricking or a feeling of swelling or burning, with spontaneous onset. It can result due to local, systemic, psychogenic or idiopathic causes. Among psychogenic causes; anxiety disorder and depression are common.”13
“Most oral paresthesias are caused by direct trauma associated with a surgical procedure, such as a dental extraction or orthognathic surgery. However, studies have shown that paresthesia also can occur after nonsurgical dentistry. The exact cause of this is not known, but it may be one or a combination of several factors: traumatic injury to the nerve via direct contact with the needle, hemorrhage into the nerve sheath, hydrostatic pressure from the injection or potential neurotoxicity from the local anesthetic itself. The hypothesis that local anesthetics may be neurotoxic is controversial.”14
Normally, paresthesia disappears after a few minutes because the pressure exerted on the nerve in question ceases. However, if paresthesia acts as a symptom of one of the aforementioned pathologies the treatment depends on the condition. Some alterations such as the deficit of certain nutrients or certain unhealthy habits can be easily remedied but other factors will require medical control. If the pain persists, your doctor or specialist can recommend the use of analgesics to relieve the discomfort.
The set of pathologies that can lead to the presence of paresthesia are very numerous. However, there are some factors that we can easily avoid. A healthy lifestyle with a proper diet and performing moderate physical exercise will help reduce the risk of paresthesia.
(1) Sharif-Alhoseini, M., Rahimi-Movaghar, V., & Vaccaro, A. R. (2012). Underlying causes of paresthesia. In Paresthesia. InTechOpen. Available online at https://www.intechopen.com/books/paresthesia/underlying-causes-of-paresthesia
(2) Al Luwimi, I., Ammar, A., & Al Awami, M. (2012). Pathophysiology of Paresthesia. In Paresthesia. IntechOpen. Available online at http://cdn.intechopen.com/pdfs/29759/InTech-Pathophysiology_of_paresthesia.pdf
(3) Tihanyi, B. T., Ferentzi, E., Beissner, F., & Köteles, F. (2018). The neuropsychophysiology of tingling. Consciousness and cognition, 58, 97-110. Available online at https://www.researchgate.net/publication/320759312_The_neuropsychophysiology_of_tingling
(4) Krishnan, U., & Moule, A. J. (2015). Mental nerve paraesthesia: A review of causes and two endodontically related cases. Saudi Endodontic Journal, 5(2), 138. Available online at http://www.saudiendodj.com/article.asp?issn=1658-5984;year=2015;volume=5;issue=2;spage=138;epage=145;aulast=Krishnan
(5) Tyler, C. R., & Allan, A. M. (2014). The effects of arsenic exposure on neurological and cognitive dysfunction in human and rodent studies: a review. Current environmental health reports, 1(2), 132-147. Available online at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4026128/
(6) Eastman, R. C. Neuropathy in Diabetes
. Available online at https://www.niddk.nih.gov/-/media/Files/Strategic-Plans/Diabetes-in-America-2nd-Edition/chapter15.pdf Available online at https://www.niddk.nih.gov/-/media/Files/Strategic-Plans/Diabetes-in-America-2nd-Edition/chapter15.pdf
(7) Green, R. (2017). Vitamin B12 deficiency from the perspective of a practicing hematologist. Blood, 129(19), 2603-2611. Available online at http://www.bloodjournal.org/content/129/19/2603?sso-checked=true
(8) Katayama, K., & Tokuda, Y. (2015). Severe Paresthesia as a Rare Presenting Symptom of Subacute Thyroiditis. General Medicine, 16(1), 26-28. Available online at https://onlinelibrary.wiley.com/doi/pdf/10.14442/general.16.26
(9) Dargahi, N., Katsara, M., Tselios, T., Androutsou, M. E., de Courten, M., Matsoukas, J., & Apostolopoulos, V. (2017). Multiple sclerosis: immunopathology and treatment update. Brain sciences, 7(7), 78. Available online at https://www.mdpi.com/2076-3425/7/7/78
(10) Easton, J. D., Saver, J. L., Albers, G. W., Alberts, M. J., Chaturvedi, S., Feldmann, E., … & Lutsep, H. L. (2009). Definition and evaluation of transient ischemic attack: a scientific statement for healthcare professionals from the American Heart Association/American Stroke Association Stroke Council; Council on Cardiovascular Surgery and Anesthesia; Council on Cardiovascular Radiology and Intervention; Council on Cardiovascular Nursing; and the Interdisciplinary Council on Peripheral Vascular Disease: the American Academy of Neurology affirms the value of this statement as an educational tool for neurologists. Stroke, 40(6), 2276-2293. Available online at https://www.ahajournals.org/doi/pdf/10.1161/strokeaha.108.192218
(11) Viera, A. J. (2003). Management of carpal tunnel syndrome. Am Fam Physician, 68(2), 265-72. Available online at http://www.sld.cu/galerias/pdf/sitios/rehabilitacion-fis/tunel_y_us.pdf
(12) Ahmad, M. (2018). The Anatomical Nature of Dental Paresthesia: A Quick Review. The open dentistry journal, 12, 155. Available online at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5838625/
(13) Bhatia, M. S., Bhatia, N. K., & Bhatia, N. K. (2015). Psychogenic Lingual Paresthesia. Journal of Clinical and Diagnostic Research: JCDR, 9(5), VD04. Available online at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4484134/
(14) Garisto, G. A., Gaffen, A. S., Lawrence, H. P., Tenenbaum, H. C., & Haas, D. A. (2010). Occurrence of paresthesia after dental local anesthetic administration in the United States. The Journal of the American Dental Association, 141(7), 836-844. Available online at https://jada.ada.org/article/S0002-8177(14)64769-3/pdf