Pinched Nerve or Nerve Compression Syndrome is also known as compression neuropathy or entrapment neuropathy. Nerve compression or entrapment neuropathy is caused by direct pressure, pinch or squeeze of peripheral or spinal nerve. Pinched or entrapped nerve causes symptoms of tingling, numbness or weakness. Nerve inflammation precedes irritation of the nerve.
What Triggers Pressure Compression of Peripheral Nerve?
Peripheral nerve is embedded within subcutaneous tissue, muscle and lies over the bone. Nerve is pinched when nerve is squeezed by surrounding soft tissue swelling, fracture fragments of bones or cartilages. Muscles, tendon or bursa may exert pressure over the peripheral nerve by forming cyst, lump or tumor.
What are the Symptoms of Peripheral Nerve Entrapment or Nerve Compression?
Symptoms caused by peripheral nerve entrapment or nerve compression are spread along the nerve and through the dermatome supplied by the entrapped nerve. Symptoms of pinched or entrap neuropathy are as follows:
Tingling and numbness along the nerve distribution.
"Pins and Needles Sensation" or a Burning Sensation.
Weakness of the muscles receiving motor nerve supply
What are the Causes of Peripheral Nerve Compression?
Causes of Peripheral Nerve Compressions are as Follows:
Occupational Injuries: Types of occupational injuries are as follows:
Positional Injury - is often caused by resting upper body on elbow continuously while at work which can cause Ulnar Nerve Compression.
Repeat Movement - Repeat movements of hand and wrist while typing and sewing can cause hypertrophy of ligaments and carpal tunnel around wrist joint. Carpal tunnel hypertrophy causes median and ulnar nerve compression at wrist. Such peripheral nerve injury is observed in individual working on computer or working as tailor.
Recurrence Vibration Movements - Frequent use of jackhammer can cause median, radial or ulnar nerve injury.
Nerve Injury Caused by Tight Fitting Braces or Cast: Peripheral nerves of upper and lower extremities may be pinched by tight braces and cast. Braces and cast are used after joint surgery and following treatment of fractured bones in extremities for several weeks. Brace or cast if tightly applied over the skin may result in pinch or squeeze of peripheral nerve. Nerve compression after application of cast or braces are frequently seen with the peripheral nerves positioned close to elbow, wrist and knee joint. Peripheral nerve compression commonly observed are radial nerve at upper extremities, ulnar nerve at elbow, median nerve at wrist and peroneal nerve at knee joint.
Tumor - Progressive growth of tumor mass at or near peripheral nerve results in nerve compression. Space occupying growth of tumors mass such as lipoma, neurofibroma and metastasis displaces surrounding soft tissue and if space is unable to expand then causes pinched and squeezing pressure over the nerve.
Cyst and Hematoma - Ganglion cyst and hematoma at or near nerve causes pressure induced ischemic changes of nerve because of compression of blood vessels. Nerve Compression or pinched nerve is often seen in extremities following soft tissue injury or fracture.
Carpal Tunnel Syndrome - Median nerve passes through carpal tunnel. Hypertrophy (thickening) of the fibrous tissue of the transverse carpal ligament causes severe pinch of median nerve. Hypertrophy or thickening of the transverse ligament is seen after trauma, repeat use of wrist, diabetes, obesity, hypothyroidism and hyperparathyroidism.
Endocrinal and Connective Tissue Diseases - Acromegaly, hypothyroidism and scleroderma causes thickening and shrinkage of soft tissue surrounding the peripheral nerve. Diseases such as acromegaly and hypothyroidism causes soft tissue hypertrophy resulting in pressure over peripheral nerve.
Peripheral Neuropathy - Diabetes may cause nerve peripheral damage such as mono-neuropathy.
What Causes Nerve Damage After a Pressure, Pinch Or Squeeze?
Nerve Ischemia (Reduced Blood Supply) - Pressure, pinch or squeeze of peripheral nerve results in compression of the blood vessels on the surface of nerve. Blood vessels running over the surface of peripheral nerve are called Vas Nervorum. Prolonged pinch or squeeze of Vas Nervorum causes nerve ischemia (lack of blood supply). Ischemic nerve initially undergoes inflammatory changes and heals with scarring. Scarring causes irreversible nerve damage.
Nerve Edema- Fluid build-up around nerve is recognized as edema. Edema is observed within myelin tissue of nerve and surrounding soft tissue. Nerve edema causes extra pressure over the nerve and results in ischemia.
What are the Tests Done to Identify Pinched Nerve or Nerve Compression?
Nerve Conduction Studies may confirm the severity of nerve injury and single or multiple nerve involvement.
Electromyography (EMG) Study includes test for muscles movement and a nerve conduction velocity test.
Which Other Medical Conditions Can Cause Pinched Nerve or Nerve Compression?
Diabetic Peripheral Neuropathy
Vitamin B12 Deficiency
Which Diseases or Conditions Causes Peripheral Nerve Compression?
Endocrinal Disease - Hypothyroidism, Acromegaly and Menopause.
Metabolic Disease- Diabetes.
Diseases of Bones and Joints - Rheumatoid Arthritis, Osteoporosis.
Which Peripheral Nerves are Affected by Nerve Compression?
Median Nerve - Carpal Tunnel Syndrome, Pronator Teres Syndrome.