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War Surgery Manual - Head Injuries. Gain the knowledge incase you find yourself without access to medical care
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  15.1 Head Injuries Chapter 15 Head Injuries Introduction The prognosis of brain injuries is good in patients who respondto simple commands, are not deeply unconscious, and do notdeteriorate. The prognosis is grave in patients who are renderedimmediately comatose (particularly those sustaining penetratinginjury) and remain unconscious for a long period of time. Anysubsequent neurologic improvement may indicatesalvageability and should prompt reevaluation. Neurosurgical damage control includes early intracranialpressure (ICP) control; cerebral blood flow (CBF) preservation;and prevention of secondary cerebral injury from hypoxia,hypotension, and hyperthemia. A motor examination of the most salvageable severely brain-injured patients will demonstrate localization to centralstimulation and these patients will require expedited treatment.Immediate intubation with adequate ventilation is the mostcritical first line of treatment for a severely head-injured patient.Evacuation to the nearest neurosurgeon, avoiding diagnosticdelays, and initiating cerebral resuscitation allow for the bestchance for ultimate functional recovery. Combat Head Injury Types  Blunt (closed head injury).  Penetrating. ! Penetrating with retained fragments. ! Perforating. ! Guttering (grooving the skull). ! Tangential. ! Cranial facial degloving (lateral temple, bifrontal).  15.2 Emergency War Surgery  Blast over-pressure CNS injuries. ! A force transmitted by the great vessels of the chest to the brain; associated with unconsciousness, confusion,headache, tinnitus, dizziness, tremors, increased startleresponse, and occasionally (in the most severe forms)increased ICP. Bleeding may occur from multiple orificesincluding ears, nose, and mouth.A combination of multiple injury types are typically involvedin combat-related brain injuries. Those injuries generally involvethe face, neck, and orbit; entry wounds may be through theupper neck, face, orbit, or temple (Fig. 15-1). Fig. 15-1. Common vectors of penetrating injury. Trans-suboccipitalTranstemporalTransfacial/infratemporalTransorbitalTransfrontal The subocciput, occiput, and retroauricular regions areoverlooked most. Injuries to these areas can indicate underlyinginjury to the posterior fossa, major venous sinus, or carotidartery, as fragments pass through the skull base. Reconstructingthe fragment path based on combination of plain films and  15.3 Head Injuries computed tomography (CT) can be challenging. In transorbital,transtemple, or penetrating injuries that cross the midline, anunderlying injury to intracranial vessels should be suspected withassociated pseudoaneurysms, dissections, or venous sinus injury.Explosion results in flying fragments, with possible vehicular-collision–associated blunt injuries. Depending on the proximityto the explosion, a blast over-pressure phenomenon may alsoresult. In a severely brain-injured patient, more deficits thanindicated by the CT scan may be due to possible underlyinginjury to brachiocephalic vessels, shear injury, or the effects of  blast over-pressure with resulting cerebral vasospasm. Plainfilms, more useful in penetrating than blunt trauma, may reveala burst fracture of the skull indicating the tremendousperforating force of a penetrating missile. Transventricular bihemispheric fragment tracts portend a poor prognosis.Severe head injuries are often seen in combination withsignificant chest, abdomen, and extremity injuries. Very rapidhemorrhage control is the priority in the noncranial injuries;utilizing damage control concepts and focusing attention on thehead injury. All efforts should be directed toward early diagnosisand intervention of the head injury. Traditional Classification of Head Injuries  Open injuries are the most commonly encountered braininjuries in combat.  Closed  injuries, seen more often in civilian settings, may havea higher frequency in military operations other than war.  Scalp  injuries may be closed (eg, contusion) or open (eg,puncture, laceration, or avulsion). ! Any scalp injury may be associated with a skull fractureand/or underlying brain injury. ! Open scalp injuries bleed profusely, even to the point of lethal blood loss, but usually heal well when properly repaired.  Skull fractures  may be open or closed, and are described aslinear, comminuted, or depressed. ! Skull fractures are usually associated with some degree of  brain injury, varying from mild concussion, to devastatingdiffuse brain injury, to intracranial hematomas.  15.4 Emergency War Surgery ! Open skull fractures are prone to infection if not properlytreated. Mechanisms of Injury  Primary injury  is a function of the energy transmitted to the brain by the offending agent. ! Very little can be done by healthcare providers to influencethe primary injury. ! Enforcement of personal protective measures (eg, helmet,seatbelts) by the command is essential prevention.  Secondary injury  results from disturbance of brain andsystemic physiology by the traumatic event. Hypotension and hypoxia are the two most acute and easilytreatable mechanisms of secondary injury. ! Other etiologies include seizures (seen in 30%–40% of patientswith penetrating brain injuries), fever, electrolyte disturbances(specifically, hyponatremia or hyperglycemia), and infection. ! All of the above conditions can be treated. ! Elevations of ICP may occur early as a result of a space-occupying hematoma, or develop gradually as a result of  brain edema or hydrocephalus. ! Normal ICP is 5–15 mm Hg, with normal cerebralperfusion pressure (CPP = MAP-ICP) usually around 70–80 mm Hg. ! Decreases in perfusion pressure as a result of systemichypotension or elevated ICP gradually result in alterationof brain function (manifested by impairment of consciousness), and may progress to global brain ischemiaand death if not treated. Patient Assessment and Triage During the primary and secondary assessment, attentionshould be placed on a complete examination of the scalp andneck. Fragments that enter the cranial vault with atranstemple, transorbital, or cross midline trajectory should be suspected as having associated neurovascular injuries.Wounds are typically contaminated by hair, dirt, and debris
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