Numbness and tingling sensation of skin are very common sensations, and we all have experienced these at some point. Most of the time, these symptoms do not point towards serious conditions. When we sleep with one arm underpinned under our body, when we sit for a long time, and when we do not move for a prolonged period of time we feel numbness or feel like many pins and needles are pricking at the skin. It is always important to know a bit about these conditions because they sometimes may be symptoms of a severe condition.
Numbness in neurological terms is defined as reduced or absent perception of sensations at a part of the body. This may be due to nerve transection, dissection, or inflammation around the nerve fibers. Sensory nerves travel from sensory organs to the thalamus via spino-thalamic tract in the spinal cord. They continue on to the cerebral cortex through the corona radiata. Lesions at the sensory organ (in this case, the skin), ascending nerve pathways, cord lesions, thalamic lesions, and radiate lesions will interfere with the perception of sensation. Strokes, tumors, metastatic cancers, spinal fractures, disk prolapse are a few commonly encountered causes for numbness. Metabolic conditions can also interfere with neuronal signal transmission. Diabetes causes a peripheral neuropathy, and mononeuritis multiplex, mononeuropathy, and polyneuropathy all of which can present with numbness. Electrolyte imbalances, especially alterations in sodium, potassium and calcium interfere with signal transmission.
Clinical examination can reveal the level of the lesion. Nerve conduction studies may give abnormal results according to the severity of the condition. Treating the root cause, rehabilitation, and supportive therapy are the principles of managing these conditions.
Tingling is also known as “pins and needles”, and it is medically known as paresthesia. It is an abnormal sensation and feels like many pins and needles pricking at the skin. This is also a very common symptom. We all have experienced it after not moving for a while or after prolonged pressure at a specific site. Saturday night palsy is a condition with an interesting story. People get drunk on Saturday nights, and when they return home they sleep on the arm chair. Arms of the man drop over the arms of the chair and the arms of the chair dig into the inner aspect of the arms of the man. This applies direct pressure over the radial nerve. There is wrist drop, pins and needles over the back of the hands. When the fibula fractures the peroneal nerve may get damaged. This results in a foot drop and paresthesia of foot. In conditions like parotid tumors, Ramsey Hunt syndrome, cerebello-pontine angle tumors, the facial nerve can get compressed. One presentation may be paresthesia of one side of the face. Nerve conduction studies, computer tomography, and magnetic resonance imaging may be needed to arrive at a definitive diagnosis.
What is the difference between Numbness and Tingling?
• Numbness is lack of or dull perception of normal sensations while tingling is an abnormal sensation.
• Numbness is due to interference of signal transmission in sensory nerves while paresthesia is due to excessive, repetitive irritation of the nerves.