Penetrating Head Trauma

Excerpt

The brain is the nervous system's central organ, responsible for coordinating and controlling various bodily functions. Briefly, the brain's main regions include the cerebral cortex, thalamus, hypothalamus, limbic system, midbrain, cerebellum, medulla oblongata, and pons. The cranial nerves emanate at different brain levels. The ventricles are the spaces inside the brain filled with cerebrospinal fluid (CSF).

Anterior and posterior arterial networks of the central nervous system form the circle of Willis. The venous sinuses drain the superficial veins, which follow the same course as their corresponding arteries. Deep brain structures also drain to the venous sinuses via deep veins.

The cranium or skull serves as the brain's protective enclosure. The frontal, parietal, temporal, occipital, sphenoid, and ethmoid bones comprise the cranium. The skull bones' thickness varies in different regions, with some areas being more vulnerable to penetrating injuries than others.

The meninges are the brain's protective coverings divided into the dura, arachnoid, and pia mater. The dura mater is the outermost layer, lying just beneath the skull. The arachnoid mater is the middle layer, separated from the dura by the subdural space. Arachnoid granulations are small outward projections of the arachnoid mater that allow CSF to re-enter the bloodstream. The subarachnoid space contains CSF. The pia mater is the innermost layer, adhering closely to the brain.

Penetrating head trauma (PHT) constitutes a foreign-body head injury breaching the skull and invariably involving the dura mater and brain. PHT is the most lethal form of traumatic head injury. Almost 70-90% of the victims die before reaching the hospital, and 50% of those reaching the hospital eventually expire in the ED during resuscitation. Recovery and rehabilitative strategies among survivors are often protracted and complicated.

The 2001 severe head injury management guidelines published by the Brain Trauma Foundation (BTF) and American Association of Neurological Surgeons (AANS) do not include PHT management algorithms. The current guidelines for managing PHT are based on military protocols during the Iraq and Afghanistan conflicts over 2 decades ago. However, a widely accepted evaluation protocol includes the primary survey, stabilization, secondary survey with detailed neurological examination, and pertinent imaging studies. The cornerstone of surgical management of PHT involves early decompression, safe debridement, and watertight dural closure.