Neuro - Head Injury & Cerebral Aneurysm

Study Notes

This presentation covers head injuries, cerebral aneurysms, and chapters 38 and 41.
Includes anatomy and physiology of the brain, cranial protection, causes of traumatic brain injury (TBI), signs of a basilar skull fracture, and the Monroe-Kellie hypothesis.

The brain is composed of various lobes (frontal, parietal, occipital, cerebellum, etc.)
The brain has structures like the tissue dividing the lateral ventricles, hypothalamus, pituitary gland, thalamus, corpus callosum, and pineal body.
The brain stem includes structures like the pons, midbrain, and medulla.

The skull protects the brain.
The layers of the meninges (dura mater, arachnoid mater, pia mater) and cerebrospinal fluid cushion the brain and protect it from injury.

The intracranial space has three components (brain tissue, cerebrospinal fluid, blood).
Total intracranial volume is fixed.
A change in the volume of one component must be compensated for by a decrease in the volume of one or both of the other components, otherwise pressure will increase.
Examples include bleeding or swelling in the brain increasing intracranial pressure.
Compensation can be normal, compensated, or decompensated (elevated) intracranial pressure (ICP) states.

Blood in the space between the dura and the skull due to damage to the middle meningeal artery.
Increased ICP leads to brain herniation.
Symptoms include a brief loss of consciousness, then a return, and dilated pupils on the affected side.
Treatment includes evacuation and cauterization.

Blood between the dura and arachnoid meningal layers, frequently in an elderly individual, caused by venous injury.
Symptoms include drowsiness, confusion, and unilateral headaches.
Treatment includes burr holes, craniotomy, and subdural drains.

Bleeding into the brain tissue itself.
Potentially due to penetrating trauma or uncontrolled high blood pressure (HTN) causing a burst cerebral aneurysm.
Symptoms include decreased consciousness, headaches, fixed/dilated pupils on the affected side, and hemiplegia depending on the location of the damage.
Treatment aims to manage increased intracranial pressure (ICP) and restore cerebral perfusion (e.g using mannitol and fluids, or potentially levophed).

Includes level of consciousness (Glasgow Coma Scale), respiration pattern (Cheyne-Stokes, hyperventilation, ataxic/agonal), pupils, eye movements (Doll's eyes, oculovestibular reflex), Babinski reflex, and posturing.

A quantitative scale assessing level of consciousness in patients with head injury.
Evaluates eye opening, best verbal response, and best motor response.

Includes alert, confused, delirious, lethargic, obtunded, stuporous, and comatose levels.
Each level has a characteristic response to stimuli, differentiated by degree of awareness and response to stimuli.

Includes spontaneous, localization, withdrawal, decortication, decerebration, and flaccid. Reflecting varying levels of neurological function.

ICP impairs cerebral perfusion and oxygenation.
Normal values range from 5-10 mmHg.
Factors increasing ICP include brain abnormalities (edema, hematomas). CSF build up (hydrocephalus, subarachnoid hemorrhage). And blood abnormalities(hypercapnia, hypoxia)
Symptoms of increasing ICP can include loss of consciousness (LOC), confusion, lethargy, ptosis (droopy eyelids), seizures, vomiting, coma, hemiplegia, posturing, changes in vital signs, and changes in respiratory pattern. Cushing triad, a warning sign for severe cases, consists of severe hypertension, wide pulse pressure, and bradycardia.

Hypoxia, suctioning, increased pCO2, positioning, and edema are among a variety of factors that increase Intracranial Pressure.

Treatment for increased ICP includes a quiet environment, elevating HOB, blood pressure control (SBP < 140 mmHg), cerebrospinal fluid (CSF) drainage, diuretics (mannitol), sedation, and anti-convulsants (levetiracetam and phenobarbital). Hyperventilation to decrease pCO2 is also a possible treatment.

Diagnosis of traumatic brain injury (TBI) involves physical examination, x-rays, head CT scans with contrast, MRIs with contrast, and lumbar punctures (LPs).