Neurology

CNS Injury, Repair and Inhibition, Excitation

CNS Injury

Acute central nervous system (CNS) injuries include stroke, traumatic brain injury, and spinal cord injury. Early brain injury is a significant cause of disability and death among patients with stroke or traumatic brain injury. The processes involved in initial brain damage after stroke and trauma are complex and not fully understood. Spinal cord injury involves damage to any part of the spinal cord or nerves at the end of the spinal canal, often leading to permanent changes in strength, sensation, and other bodily functions below the site of the trauma.

Types of CNS Injury

• Primary Injury: Immediate damage caused by the initial event (e.g., impact or lack of blood flow).
• Secondary Injury: Subsequent cellular and biochemical processes that exacerbate the initial injury.
• Focal Injury: Damage localized to a specific area of the brain or spinal cord.
• Diffuse Injury: Widespread damage affecting multiple areas.
• Open/Penetrating Injury: Injury resulting from an object piercing the skull or spinal column.
• Closed/Non-Penetrating Injury: Injury without any breach in the skull or spinal column.

Repair and Inhibition

Repair refers to the regrowth or restoration of nervous tissues, cells, or cell products. This process may involve the generation of new neurons, glia, axons, myelin, or synapses. Neuroregeneration varies between the peripheral nervous system (PNS) and the central nervous system (CNS), particularly concerning the extent and speed of repair.

• In the case of axonal injury, the distal segment undergoes Wallerian degeneration, losing its myelin sheath. The proximal segment may die through apoptosis or attempt repair via chromatolytic reaction.
• In the CNS, synaptic stripping occurs as glial cells invade the damaged synapse, hindering regeneration.

Inhibition: The process by which nerves can retard or prevent the functioning of an organ or part.