Management of Increased ICP

Question 1. Discuss the clinical manifestations and management of increased ICP.
Answer:

Raised Intracranial Pressure

• Normal ICP in adults is <10–15 mm Hg. There are normal regular waves due to pulse and respiration.
• With increased pressure “pressure waves” appear. With the continued rise of ICP, perfusion pressure (PP) falls.
• When PP falls CBF is reduced. Electrical cortical activity fails if CBF is 20 mL/100 g/min.
• When ICP reaches MAP circulation to the brain stops.
• Raised intracranial pressure (RIP) may be caused by mass lesions, cerebral edema, obstruction to CSF circulation causing hydrocephalus, impaired CSF absorption, and cerebral venous obstruction.

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Common Causes of Raised Intracranial Pressure

Clinical Features

• Signs and symptoms of the underlying cause.
• Features of raised ICP
• The speed of increase in the pressure influences presentation.
• Acute: If ICP has risen acutely (as in aggressive tumors), there is no time for compensatory mechanisms to develop and causes leading early symptoms, including sudden death.
• The pulse rate is slower, BP may be elevated (Cushing’s reflex), and respiratory depression (Cushing’s triad).
• Slow: Compensatory mechanisms develop (e.g., alteration in the volume of fluid in CSF spaces and venous sinuses) which minimize symptoms.
• Raised ICP of more than a few days will result in papilledema.
• 4th cranial nerve palsy: Due either to stretching of the long slender nerve or to compression against the petrous temporal bone ridge.
• It may be unilateral or bilateral.
• Other cranial nerves III, V, and VII may also be involved.

Herniation Syndromes

• Raised ICT may cause displacement and herniation of the brain. Types of herniation are presented

Supratentorial Herniation

• Uncal: Most frequent herniation in which downward displacement of the medial temporal lobe (uncus) through the tentorium occurs.
• Results in ipsilateral pupil dilatation, decreased level of consciousness, changes in respiratory patterns, respiratory arrest, and contralateral hemiplegia.
• Subfalcine herniation results in opposite lower limb weakness (ACA involvement).
• Central/Transtentorial Herniation
• Results in loss of consciousness, small reactive pupils advancing to fixed/dilated pupils, respiratory changes leading to respiratory arrest and decorticate posturing advancing to flaccidity.

Infratentorial Herniation

Downward herniation of the cerebellar tonsils through the foramen magnum may compress the medulla oblongata (tonsillar coming) causing respiratory and cardiac arrest.

Features of raised intracranial pressure (ICP).

Diffuse anterior headache worse on lying/straining

Vomiting

• Diplopia (VIth nerve involvement)
• Papilledema
• Bradycardia raised blood pressure

Impaired conscious level: Drowsiness and mental deterioration

• Seizures
• Types of herniation.

Uncal Syndrome

• Herniation of the temporal lobe (medial) transtentorial results in uncle syndrome.
• It produces drowsiness in the early stages and is accompanied by unilateral pupillary dilatation.
• Sometimes due to the lateral mass effect, the opposite cerebral peduncle is crushed against the tentorium.
• This causes Babinski sign and weakness of the arm and leg ipsilateral to the lesion (Kernohan–Woltman sign).

Investigations

• Depending on the underlying lesion/etiology.
• CT head: It may show midline shift and compression of basal cisterns.
• ICP monitoring: It is done in selected cases. For example, patients with GCS < 8 and CT scan show hematoma, contusion, edema, herniation, or compressed basal cisterns.

Question 123. Discuss the management of increased ICP.
Answer:

Treatment/Management of Increased Intracranial Pressure

Aims of management of increased intracranial pressure.

• Relieve the cause (e.g., surgical decompression of mass)
• Steroids to reduce vasogenic edema or shunt
• Procedure to relieve hydrocephalus
• Supportive treatment: Maintenance of fluid balance, blood pressure control, head elevation, and use of diuretics such as mannitol. Intensive care support may be required.

Airway management

Glasgow Coma Scale < 8 requires intubation to protect the airway.

Head positioning: The head should be kept in the midline, with around 15– 30° elevation.

Temperature control: Temperature can be lowered with acetaminophen and cooling blankets.

Shivering is prevented by neuromuscular block.

Hemodynamic management: Maintain MAP > 90 mm Hg. Administer normal saline to achieve a central venous pressure of 5–10 mm Hg.

Serum sodium is to be maintained between 140 and 150 mmol/L.

Seizure management: Prophylactic antiepileptics (phenytoin).

Analgesia, sedation, and neuromuscular block

Analgesia: Opioid like fentanyl and morphine

Sedation: Benzodiazepines like lorazepam and midazolam

Neuromuscular block: Pancuronium and vecuronium.

Specific Therapy

Mannitol: Osmotic diuretic

Mechanism: Rheologic and osmotic

Adverse effect:

• Intravascular volume depletion and
• Acute renal failure
• Glycerol acts in a similar fashion but is used less often.
• Glycerol has caloric value and is beneficial for nutritional support.
• The renal function does not determine the diuretic action. Hence, it can be given to patients with renal insufficiency.
• Side effect: is intravascular hemolysis, which can be prevented by giving a low concentration (<20%) at a slow infusion rate (>1 hour).
• Glycerol is most effective via intraduodenal administration.
• Frusemide: 20 mg 8 hourly.
• Hypertonic saline: A more recent treatment for increased ICP is IV administration of 3–23.4% hypertonic saline.
• IV boluses can reduce ICP and augment CPP for several hours. Creates an osmotic gradient and draws water from the intracellular and extracellular spaces into the intravascular compartment.

Potential side effects

The trauma guidelines recommend: Continuous infusion of 3% saline between 0.1 and 1.0 mL/kg/h. Administration on a sliding scale, with the minimal dose needed to maintain ICP <20 mm Hg. Care is to be taken while using hypertonic saline to decrease ICP, the osmolarity has to be maintained below 360 mOsm/L.

Steroids: Dexamethasone 4 mg 6 hourly. Helps only in reducing vasogenic edema around the tumor, abscesses, or subdural hematomas.

Routine administration of steroids should be avoided in patients with traumatic brain injury and raised ICP.

Barbiturate coma in refractory cases: Pentobarbital 5 mg/kg lowers ICP by lowering the rate of the body’s metabolic process, oxygen consumption, and carbon dioxide production.

Burst suppression correlates with maximal metabolic suppression.

Hyperventilation: The mechanism by which hyperventilation decreases raised intracranial tension is by decreasing cerebral blood volume by vasoconstriction.

• Hyperventilation resulting in a drop in PaCO2 to around 25–35 decreases CBF.
• Management of underlying cause wherever possible or applicable.
• Aims of management of increased intracranial pressure.
• Relieve the cause (e.g., surgical decompression of mass)
• Steroids to reduce vasogenic edema or shunt Procedure to relieve hydrocephalus
• Supportive treatment: Maintenance of fluid balance, blood pressure control, head elevation, and use of diuretics such as mannitol. Intensive care support may be required

Side effects of treatment by hypertonic

• saline in raised ICP.
• Hyperosmolar central pontine myelinolysis
• Congestive heart failure
• Subdural hematomas
• Coagulopathy (rarely)
• Surgical Management
• Management of underlying cause of raised ICP.

Mass lesion: Surgical decompression of mass lesion, removal of space-occupying lesion.

Surgical decompression is a lifesaving procedure in which limited frontal or temporal lobectomies are done.

Hydrocephalus: Ventriculoatrial or ventriculoperitoneal shunting.

Tumors Of The Nervous System

• Among CNS tumors glial tumors are the most common, accounting for 50–60% of primary brain tumors.
• Meningiomas account for about 25% and schwannomas for about 10%. A few primary tumors.
• Cerebellopontine Angle Tumors