neurologic disorders
Brain Herniation
Treatment of Brain Herniation
Immediate stabilization (airway, breathing, circulation, or ABCs) Admission to an intensive care unit (ICU) Supportive measures, including control of ICP Treatment of underlying disorder Treatment of brain herniation is similar to Treatment . The cause of brain herniation is treated when possible. Hypotension must be corrected. Patients are admitted to the ICU so that respiratory and neurologic status can be monitored. Patients must be stabilized. Airway, breathing, and circulation must be ensured immediately. If increased ICP is suspected, intubation should be done via rapid-sequence Endotracheal intubation (using a paralytic drug) rather than via nasotracheal intubation; nasotracheal intubation in a patient who is breathing spontaneously causes more coughing and gagging, thus increasing ICP, which is already increased because of intracranial abnormalities. If ICP is increased, intracranial and cerebral perfusion pressure should be monitored (see Intracranial Pressure (ICP) Monitoring ), and pressures should be controlled. The goal is to maintain ICP at ≤ 20 mm Hg and cerebral perfusion pressure at 50 to 70 mm Hg. Cerebral venous drainage can be enhanced (thus lowering ICP) by elevating the head of the bed to 30° and by keeping the patient’s head in a midline position. Intracranial pressure control include Sedation:Sedatives may be necessary to control agitation, excessive muscular activity (eg, due to delirium), or pain, which can increase ICP. Hyperventilation:Hyperventilation causes hypocapnia, which causes vasoconstriction, thus decreasing cerebral blood flow globally. Hydration:Isotonic fluids are used. Providing free water through IV fluids (eg, 5%dextrose, 0.45% saline) can aggravate cerebral edema and should be avoided. Fluids may be restricted to some degree, but patients should be kept euvolemic. If patients have no signs of dehydration or fluid overload, IV fluids with normal saline can be started at 50 to 75 mL/h. The rate can be increased or decreased based on serum sodium, osmolality, urine output, and signs of fluid retention (eg, edema). Diuretics:Serum osmolality should be kept at 295 to 320 mOsm/kg. Osmotic diuretics (eg,mannitol) may be given IV to lower ICP and maintain serum osmolality. These drugs do not cross the blood-brain barrier. They pull water from brain tissue across an osmotic gradient into plasma, eventually leading to equilibrium. Fluid and electrolyte balance should be monitored closely while osmotic diuretics are used. A 3% saline solution is another potential osmotic agent to control ICP. Blood pressure (BP) control:Systemic antihypertensives (eg, calcium channel blockers) are needed only when hypertension is severe (> 180/95 mm Hg). How much BP is reduced depends on the clinical context. Systemic BP needs to be high enough to maintain cerebral perfusion pressure even when ICP increases. Corticosteroids:Corticosteroids are effective only for tumors and sometimes abscesses of the brain when vasogenic edema (due to disruption of the blood-brain barrier, as may result from tumors or abscesses) is present. Corticosteroids are ineffective for cytotoxic edema (due to cell death and breakdown) and can increase plasma glucose, exacerbating cerebral ischemia. Removal of cerebrospinal fluid (CSF): When ICP is increased, CSF can be removed at periodic intervals; it is removed slowly, at a reduced rate of 1 to 2 mL/minutes to help lower ICP. Position:Positioning the patient to maximize venous outflow from the head can help minimize increases in ICP. The head of the bed can be elevated to 30° (with the head above the heart) as long as cerebral perfusion pressure remains at the desired range. The patient’s head should be kept in a midline position, and neck rotation and flexion should be minimized. Tracheal suctioning, which can increase ICP, should be limited. If ICP continues to increase despite other measures to control it, the following may be used: When ICP is increased after head trauma or cardiac arrest, hypothermia in the range of 32 to 35° C has been used to reduce ICP to < 20 mm Hg. However, use of hypothermia to lower ICP is controversial; some evidence ( Treatment references ) suggests that this treatment may not effectively lower ICP in adults or children and may have adverse effects. Pentobarbitalcoma:Pentobarbitalcan reduce cerebral blood flow and metabolic demands. However, its use is controversial because the effect on clinical outcome is not consistently beneficial, and treatment withpentobarbitalcan lead to complications (eg, hypotension). In some patients with refractory intracranial hypertension that does not respond to standard hyperventilation and hyperosmolar therapy,pentobarbitalcan improve functional outcome. Craniotomy with duraplasty can be done to provide room for brain swelling. This procedure can prevent deaths, but overall functional outcome may not improve much, and it may lead to complications such as hydrocephalus in some patients ( Treatment references ). It may be most useful for large cerebral infarcts with impending herniation, particularly in patients < 50 years. Brain herniation due to tumors is treated withmannitol(recommended dosage is 0.5 to 1.5 g/kg/dose IV withmannitol20 to 25% concentration every 4 to 6 hours as required,) a corticosteroid (eg,dexamethasone16 mg IV, followed by 4 mg orally or IV every 6 hours), and endotracheal intubation. Hyperventilation to a carbon dioxide partial pressure (PCO2) of 26 to 30 mm Hg can help decrease ICP temporarily in emergencies. Mass lesions should be surgically decompressed as soon as possible. 1.Moler FW, Silverstein FS, Holubkov R, et al: Therapeutic hypothermia after in-hospital cardiac arrest in children.N Engl J Med376 (4):318-329, 2017. doi: 10.1056/NEJMoa1610493 2.Su TM, Lan CM, Lee TH, et al: Risk factors for the development of posttraumatic hydrocephalus after unilateral decompressive craniectomy in patients with traumatic brain injury.J Clin Neurosci63:62-67, 2019. doi: 10.1016/j.jocn.2019.02.006 Epub 2019 Mar 1. 