Numbness, a sensation characterized by a loss or decrease in feeling, is a common experience for many individuals. While often temporary and harmless, it can sometimes signal an underlying health condition that requires medical attention.
Understanding Numbness
Numbness involves a diminished or complete absence of sensation in a specific body part. This sensation arises from a disruption in the communication pathways between the body and the brain. Sensory nerves act like communication cables, transmitting information about touch, temperature, and pain to the brain and spinal cord.
When these nerve signals are interrupted or altered, the brain receives incomplete or no information, leading to numbness. This interruption can occur due to pressure, nerve irritation, or damage to the nerve. The sensation can manifest as tingling, prickling, or a “pins and needles” feeling.
Common Causes of Numbness
Temporary numbness often results from everyday situations that briefly compress nerves. A common example is a limb “falling asleep” after sustained pressure, such as sitting cross-legged or sleeping with an arm tucked beneath the head. This pressure temporarily restricts the nerve’s ability to transmit signals.
Once the pressure is relieved, the sensation typically returns within minutes as nerve signals normalize. Minor injuries can also cause transient numbness by temporarily affecting localized nerves. Exposure to cold temperatures can similarly lead to temporary numbness as blood flow to the affected area decreases, impacting nerve function.
Urgent Signs to Consult a Neurologist
While many instances of numbness are not serious, certain accompanying symptoms warrant immediate evaluation by a neurologist. Sudden onset of numbness, particularly if it affects an entire arm or leg, or one side of the body, can be a sign of a stroke or other serious neurological event.
Numbness that progressively worsens or is persistent should also prompt a neurological assessment. If numbness is accompanied by muscle weakness, paralysis, or difficulty controlling movements, it suggests a more significant nerve or brain issue. For instance, a weak handgrip affecting daily activities or foot drop, which causes difficulty lifting the front of the foot, can be concerning signs.
Other neurological symptoms alongside numbness are important indicators. These include changes in vision, such as blurriness or double vision, or speech difficulties like slurred speech or trouble finding words. Problems with balance, coordination, or sudden dizziness, especially if combined with numbness, also necessitate prompt medical attention.
A severe headache that appears suddenly, particularly if unlike any experienced before, along with confusion or disorientation and numbness, are red flags. Numbness that develops after a recent head injury, even if the injury seemed minor, requires evaluation due to the potential for underlying cranial nerve damage or brain issues. Additionally, if numbness affects the “saddle area” (thighs, buttocks, genitals) and is associated with loss of bladder or bowel control, it indicates a serious spinal cord issue requiring urgent care.
What a Neurologist Does
A neurologist is a medical doctor specializing in disorders of the brain, spinal cord, and nerves. When evaluating numbness, a neurologist begins by taking a comprehensive patient history, asking about the nature, onset, duration, and associated symptoms. They also inquire about other medical conditions and lifestyle factors.
Following the history, a neurological examination assesses various aspects of the nervous system. This includes testing sensation, reflexes, muscle strength, balance, and coordination. The neurologist may use instruments like a pin, cotton swab, or tuning fork to check how well a patient can feel different sensations.
Based on the findings from the history and physical examination, the neurologist may order diagnostic tests to pinpoint the cause of the numbness. Common tests include nerve conduction studies (NCS) and electromyography (EMG), which measure the electrical activity and speed of nerve signals. Imaging studies, such as magnetic resonance imaging (MRI) or computed tomography (CT) scans, are often used to visualize the brain and spinal cord, looking for nerve compression, tumors, or other structural abnormalities. Blood tests can also be conducted to check for underlying conditions like vitamin deficiencies or diabetes, which can contribute to numbness.