Spinal Cord Transection Overview

Spinal Cord Transection

• Causes:
  • Road accidents causing vertebral fractures
  • Primary tumors or metastasis from malignant tumors

Complete Transection (T.S.)

• Clinical Manifestations: Determined by the lesion's extent.
  • Upper Cervical Level: Immediate death due to paralysis of all respiratory muscles.
  • Lower Cervical Level: Quadriplegia, but diaphragmatic breathing still possible.
  • Thoracic Region: Normal respiration, but paralysis of lower limbs (paraplegia).

Effects of Complete Transection

• Sensations: Loss below the lesion level
• Voluntary Movements: Loss below the lesion level
• Reflexes: Loss below the lesion level

Complete Transection (T.S.) Damage

• Permanent Loss: Complete T.S. leads to permanent loss of sensations and voluntary movements below the lesion level. This damage arises from the sectioning of all sensory and motor tracts.

Stage of Spinal Shock

• Occurrence: Immediately after transection.
• Cause: Sudden withdrawal of facilitatory supraspinal impulses (corticospinal, reticulospinal, vestibulospinal tracts).
• Membrane Potential: Resting membrane potential of spinal motor neurons is 2-6 mV higher than normal. (hyperpolarized; e.g. -72 to -76 mV).
• Duration: Variable depending on the brain's development, and generally lasts 2-6 weeks.

Manifestations Below the Lesion

• Reflexes: Loss of all reflexes (superficial, deep, visceral).
  • Deep Reflexes: Absent tendon jerks
  • Muscle Tone: Flaccid muscles, reduced muscle pump efficiency, causing reduced venous return and cold, blue limbs.
  • Visceral Reflexes: Loss of micturition, defecation, and erection.
  • Retention with Overflow: Internal sphincter tone rapidly returns while bladder and rectal walls remain paralyzed, resulting in urine accumulation and eventually dribbling.

Loss of Vasomotor Tone

• Cause: Interruption of connecting fibers between vasoconstrictor centers and lateral horn cells of the spinal cord (preganglionic sympathetic).
• Effect: Immediate drop in blood pressure, inversely proportional to section level.

Bed Sores (Decubitus Ulcers)

• Cause: Body weight restricts blood circulation to the skin, leading to skin sloughing.
• Location: Commonly found over bony prominences (e.g. back, heels, gluteal region).
• Prevention: Frequent patient repositioning and hygiene to prevent pressure.

Stage of Recovery of Reflexes

• Recovery: After spinal shock ends, some reflex activity returns, and the excitability of spinal cord centers is restored.
• Cause of recovery: Denervation hypersensitivity to the chemical transmitters released by remaining spinal excitatory endings develops.
• Sprouting of collaterals: Existing neurons sprout collaterals, forming additional excitatory endings on interneurons and motor neurons

Recovery Features

• Early Recovery:
  • Gradual rise in arterial blood pressure, due to regained spinal vasomotor centre activity. However, patient can rapidly develop a sudden drop in blood pressure on movement.
  • Return of flexor reflexes earlier than extensors, leading to paraplegia being in the flexor position.
  • Positive Babinski sign and return of other deep reflexes later.
  • Improvement in circulation through limbs due to arteriole/venule tone return.
  • Return of visceral reflexes (bladder and bowel function—automatic evacuation returns but voluntary control is lost).
• Mass Reflex: Painful skin stimuli can cause flexion withdrawal, bladder evacuation, rectal evacuation and sweating. Increases in blood pressure can be used to initiate bladder and bowel function.
• Sexual reflexes: Genital manipulation can cause erection and ejaculation.

Advanced Stage of Recovery

• Management: Proper patient care involving mobility, antibiotics, nutrition, and fluid balance is crucial for improved recovery. This can reduce mortality from 80% to 6%.
• Tone in Extensor Muscles: Gradually increase in tone in extensor muscles, leading to extension of lower limbs (paraplegia in extension).
• Positive Supporting Reflexes: Well-developed positive supporting reflexes allowing the patient to stand.
• Reflex Failure: This possibility can result from complications like infection, malnutrition, and others arising from the cord transection interfering with spinal reflex activity.