Disordered Sensations: Paresthesia & Allodynia

Disordered Sensations

• Sensory tract lesions can lead to disordered sensations.
• Paresthesia is characterized by abnormal, positive sensations.
• Dysesthesia is characterized by an unpleasant, abnormal sensation.
• Allodynia is pain caused by a non-noxious stimulus.
• Hyperalgesia (Hyperpathia) is increased pain response to a noxious stimulus.

General Symptoms

• Lesions in the posterior column-medial and lemniscal pathway typically cause tingling, numbness, or a tight band-like sensation around the body, which can blunt discriminatory touch.
• Lesions of the anterolateral pathway typically cause burning or sharp pain.
• Parietal lobe lesions cause numbness or tingling, contralaterally, and possible pain.
• Thalamus lesions can cause severe contralateral pain, known as Dejerine-Roussy syndrome.
• Cervical spine lesions may be accompanied by Lhermitte's sign, which presents like an electricity-like sensation running down the back and into the extremities upon neck flexion.

Causes of Spinal Cord Injuries

• Spinal cord injuries can be caused by contusions.
• Compression from disc herniation, degenerative spine disorders, or disc embolus contributes to spinal cord injuries.
• Vascular issues like anterior spinal artery infarct or spinal dural arteriovenous malformation (AVM), and epidural hematoma are causes of spinal cord injuries.
• Nutritional deficiencies in Vitamin B12 and Vitamin E can cause spinal cord injuries.
• Infections such as epidural abscesses and viruses, including HIV, Lyme disease, tertiary syphilis, and schistosomiasis, can cause spinal cord injuries.
• Autoimmune disorders like multiple sclerosis, Lupus, and postinfectious myelitis can cause spinal cord injuries.
• Cancers, including epidural metastasis, meningioma, schwannoma, astrocytoma, ependymoma, and hemangioblastoma, contribute to spinal cord injuries.
• Developmental conditions like spina bifida, Chiari malformation, and syringomyelia can cause spinal cord injuries.

Spinal Cord Injuries

• Symptoms may be associated with the specific segment of the cord that is injured.
• Spinal shock may occur with acute injuries (trauma).
• Spinal shock is characterized by flaccid paralysis, loss of deep tendon/stretch reflexes, and decreased blood pressure due to decreased sympathetic stimulation of blood vessels.
• Spasticity and upper motor neuron signs usually develop later.

Spinal Cord Injury Types

• Cord transection involves the loss of vibration and position sense (V), pain and temperature sense (P), and motor loss (M).
• Cord hemi-section results in loss of vibration and position sense (V), motor Loss (M), and pain and temperature sense (P).
• Central cord lesions involve loss of pain and temperature sense (P), vibration and position sense (V), and motor Loss (M)
• Posterior cord syndrome involves the loss of vibration.
• Anterior cord syndrome involves the loss of pain, temperature and motor function.