Head, Spine, and Nervous System Trauma

Head, Spine, and Nervous System Trauma

Primary vs. Secondary Brain Injury

Traumatic brain injury (TBI) results from two distinct processes. Primary injury occurs at the moment of impact: skull fractures, contusions, lacerations, and diffuse axonal injury caused directly by mechanical forces. You cannot reverse primary injury in the field. Your entire focus is preventing secondary injury — the cascade of physiological events that destroys viable brain tissue in the hours after the initial event.

Secondary injury is driven by hypoxia, hypotension, hypercapnia, hyperthermia, and rising intracranial pressure (ICP). Even a brief episode of hypoxia (SpO₂ below 90%) or hypotension significantly worsens outcomes. Maintain a patent airway, deliver supplemental oxygen to keep SpO₂ at or above 94%, and support perfusion. Avoid aggressive hyperventilation except as a temporary bridge for impending herniation — it causes cerebral vasoconstriction and ischemia if used routinely.

Severity Classification and the Glasgow Coma Scale

The Glasgow Coma Scale (GCS) is the standard tool for classifying TBI severity and tracking neurological trends. It scores three components:

| Component | Best Response | Score Range |

|---|---|---|

| Eye Opening (E) | Spontaneous | 1–4 |

| Verbal Response (V) | Oriented | 1–5 |

| Motor Response (M) | Obeys commands | 1–6 |

Total GCS = E + V + M (range 3–15)

• Mild TBI: GCS 13–15
• Moderate TBI: GCS 9–12
• Severe TBI: GCS 3–8

Always document all three subscores separately (e.g., E3V4M5 = GCS 12) so receiving clinicians can track deterioration or improvement in each component. A decreasing GCS — even a single-point drop in motor score — is a red flag requiring immediate reassessment and expedited transport.

Motor scoring tip: Abnormal flexion (decorticate posturing) scores 3; abnormal extension (decerebrate posturing) scores 2. Both indicate severe injury. No motor response scores 1.

Herniation: Recognize It Immediately

Herniation occurs when rising ICP forces brain tissue through rigid compartments. It is an immediate life threat. Classic signs include:

• Cushing's Triad: hypertension (widening pulse pressure), bradycardia, and irregular respirations. This triad indicates severely elevated ICP and imminent brainstem compression. It is a late, ominous finding.
• Unilateral or bilateral fixed, dilated pupil(s): compression of cranial nerve III. A unilateral blown pupil on the same side as a mass lesion is classic for uncal herniation.
• Posturing: decorticate or decerebrate posturing emerging or worsening.
• Rapid neurological decline: sudden drop in GCS, especially motor score.

If herniation signs are present, brief, controlled hyperventilation (targeting end-tidal CO₂ approximately 35–40 mmHg as a baseline; lower only transiently per medical direction for active herniation) is acceptable as a temporizing measure while you transport immediately. Follow your local protocols and medical direction.

Spinal Motion Restriction: Current Evidence-Based Approach

Routine full spinal immobilization of every trauma patient is no longer supported by evidence. The National Association of EMS Physicians (NAEMSP) and associated organizations have published position statements supporting selective spinal motion restriction (SMR) — applying restriction only when clinical criteria indicate risk of spinal injury.

Key clinical decision criteria for SMR include:

• Altered mental status or GCS below 15 (including intoxication)
• Spinal pain or midline tenderness on palpation
• Neurological deficit (weakness, numbness, paresthesia)
• Anatomic deformity of the spine
• High-energy mechanism with a distracting injury that may mask spinal symptoms
• Patient cannot be reliably assessed (uncooperative, intoxicated, language barrier)

If none of these criteria are present, the patient is typically a candidate for selective assessment without full restriction. Document your assessment findings and the rationale for your decision clearly.

Distracting injuries are a critical concept: a painful long-bone fracture or significant soft-tissue injury may prevent the conscious patient from accurately reporting spinal pain, making clinical clearance unreliable. In those cases, apply SMR.

Manual stabilization of the head and cervical spine is appropriate while your assessment is conducted. Current evidence does not support rigid cervical collars uniformly improving outcomes; their use should follow local protocol and medical direction. The emphasis is on minimizing unnecessary movement while not delaying transport or airway management.

Safety Priorities in Practice

• Airway first: a combative or unconscious TBI patient with a threatened airway requires definitive management before spinal restrictions create delay.
• Never sacrifice airway or perfusion for spinal precautions.
• Reassess GCS frequently and document the time of each measurement.
• Communicate GCS score and trend clearly during patient handoff.
• Follow your jurisdiction's specific SMR protocol — state and agency guidelines may specify assessment tools (such as the NEXUS criteria or Canadian C-Spine Rule principles adapted for EMS) that apply in your system.