Sep 85 min read

What are the causes of a score drop in the Glasgow Coma Scale (GCS)

A summary table of the causes of a drop in Glasgow Coma Scale (GCS), categorized by intracranial and extracranial causes for easy reference:

Category	Cause	Key Points	Diagnostic Approach	Management
Intracranial (In Brain)	Encephalitis	Brain inflammation (viral/autoimmune), fever, headache, altered mental status	MRI, CSF analysis (lymphocytosis, PCR for viral DNA)	Antivirals (e.g., acyclovir), supportive care, ICP management
	Hydrocephalus	CSF accumulation, acute (headache, vomiting) or chronic (cognitive decline)	CT/MRI (ventricular dilation)	Ventriculoperitoneal shunt, endoscopic third ventriculostomy
	Traumatic Brain Injury	Head trauma, contusions, hemorrhages, cerebral edema	CT (to detect bleeding, fractures), MRI (for diffuse axonal injury)	Airway protection, ICP management, surgical decompression if needed
	Stroke (Ischemic/Hemorrhagic)	Sudden focal deficits, altered consciousness	CT (rule out hemorrhage), MRI (ischemic changes)	tPA for ischemic stroke, blood pressure control, surgical management for hemorrhagic stroke
	Brain Tumor	Headache, seizures, focal deficits, increased ICP	MRI with contrast	Surgery, radiation, chemotherapy, corticosteroids for ICP
	Brain Abscess	Focal infection, fever, neurological deficits, headache	MRI/CT with contrast, blood cultures	Antibiotics, drainage of abscess
Extracranial (Out Brain)	Electrolyte Imbalance	Hyponatremia, hypernatremia, hypocalcemia, hypercalcemia	Serum electrolytes	Correction of electrolyte imbalance, treat underlying condition
	Hypoglycemia	Low blood glucose, confusion, seizures, coma	Blood glucose test	Immediate glucose administration (oral or IV)
	Hypoxia	Oxygen deprivation, restlessness, confusion	Pulse oximetry, ABGs	Oxygen supplementation, treat underlying cause (e.g., respiratory failure)
	Toxic Metabolic Encephalopathy	Organ failure (hepatic, renal), confusion, asterixis	Liver/renal function tests, ammonia level	Treat underlying condition (e.g., lactulose for hepatic encephalopathy, dialysis)
	Intoxication	Alcohol, opioids, CNS depressants, altered consciousness	Toxicology screen	Specific antidotes (e.g., naloxone), supportive care
	Sepsis	Systemic infection, fever, confusion, shock	Blood cultures, lactate, infection markers	Broad-spectrum antibiotics, fluid resuscitation
	Hypercapnia	CO2 retention (e.g., COPD), confusion, lethargy	ABGs showing high CO2	Improve ventilation (e.g., non-invasive ventilation, intubation)
	Hypothermia	Low body temperature, confusion, coma	Core body temperature	Gradual rewarming, supportive care, treat underlying cause

Intracranial causes of altered consciousness and brain injury, such as encephalitis, hydrocephalus, traumatic brain injury (TBI), stroke, and brain tumors, each have distinct pathophysiological mechanisms, clinical presentations, diagnostic approaches, and management strategies. These conditions require a systematic understanding to ensure accurate diagnosis and effective treatment.

Intracranial Causes (In the Brain)

Encephalitis

Pathophysiology: Encephalitis is primarily caused by viral infections like herpes simplex virus (HSV) and West Nile virus. It may also arise from autoimmune processes, leading to brain inflammation. This results in cerebral edema, increased intracranial pressure (ICP), and disruption of neuronal function.
Clinical Presentation: Patients commonly exhibit fever, headache, altered mental status, seizures, and focal neurological deficits. Severe cases may present with a significantly decreased Glasgow Coma Scale (GCS).
Diagnosis: Clinical presentation is key, supported by cerebrospinal fluid (CSF) analysis showing lymphocytic pleocytosis, elevated protein, and normal glucose. MRI may reveal specific findings, such as temporal lobe involvement in HSV encephalitis. PCR testing confirms the viral etiology.
Management: Early empirical antiviral therapy, such as acyclovir for HSV, is critical. Supportive care and management of elevated ICP are also essential.

Hydrocephalus

Pathophysiology: This condition arises due to an imbalance in cerebrospinal fluid (CSF) production and absorption, leading to ventricular dilation and increased ICP. It may be classified as communicating or non-communicating, based on whether the CSF flow is obstructed.
Clinical Presentation: Acute hydrocephalus presents with headache, nausea, vomiting, papilledema, and altered mental status. Chronic cases might show cognitive decline or gait disturbances.
Diagnosis: Neuroimaging via CT or MRI is essential. MRI is preferred for assessing ventricular dilation and identifying any obstruction, such as tumors.
Management: Treatment involves addressing the underlying cause. Procedures such as ventriculoperitoneal (VP) shunting or endoscopic third ventriculostomy may be necessary.

Traumatic Brain Injury (TBI)

Pathophysiology: TBI results from mechanical forces that cause primary injuries (e.g., contusions, hemorrhages) and secondary injuries (e.g., cerebral edema, ischemia). Increased ICP and impaired cerebral perfusion are common.
Clinical Presentation: Symptoms vary from mild concussion to severe coma. Worsening GCS often indicates progressive brain injury.
Diagnosis: CT scanning is the initial imaging modality to assess hemorrhages or fractures. MRI can later evaluate diffuse axonal injury.
Management: Immediate stabilization (airway, breathing, circulation) is crucial. Measures to lower ICP, including head elevation and hyperosmolar therapy, are used alongside surgical interventions if required.

Stroke (Ischemic and Hemorrhagic)

Pathophysiology: Ischemic strokes are caused by arterial occlusion, while hemorrhagic strokes result from vessel rupture. Both disrupt brain function, potentially leading to rapid decreases in GCS.
Clinical Presentation: Symptoms depend on the brain area affected, commonly presenting with hemiparesis, aphasia, or visual deficits. Large strokes or brainstem involvement can cause significant drops in consciousness.
Diagnosis: Non-contrast CT is used to rule out hemorrhage, with MRI providing more detail on ischemic strokes. Angiography may detect vascular occlusions or aneurysms.
Management: Treatment depends on stroke type—thrombolysis or thrombectomy for ischemic strokes, and blood pressure control with surgical intervention for hemorrhagic strokes.

Brain Tumors

Pathophysiology: Tumors, whether primary or metastatic, can invade brain tissue, elevate ICP, or cause obstructive hydrocephalus.
Clinical Presentation: Symptoms vary by location and tumor size but often include headaches, seizures, and focal deficits. GCS reduction suggests increasing ICP or herniation risk.
Diagnosis: MRI with contrast is the preferred imaging to assess tumor characteristics.
Management: Options include surgical resection, radiation therapy, chemotherapy, and symptom management, such as corticosteroids to reduce ICP.

Extracranial Causes (Outside the Brain)

Electrolyte Imbalances

Pathophysiology: Disorders like hyponatremia or hypercalcemia alter neuronal excitability, affecting mental status.
Clinical Presentation: Symptoms include confusion, seizures, and coma. Specific signs vary based on the electrolyte abnormality.
Diagnosis: Blood tests confirm the electrolyte derangements.
Management: Correct the imbalance through fluid or electrolyte therapy, depending on the cause.

Hypoglycemia

Pathophysiology: Insufficient glucose impairs neuronal function, causing neuroglycopenia.
Clinical Presentation: Symptoms range from confusion to coma.
Diagnosis: Bedside glucose tests.
Management: Immediate glucose administration and treatment of the underlying cause.

Hypoxia

Pathophysiology: Low oxygen impairs brain metabolism, leading to neuronal injury.
Clinical Presentation: Acute hypoxia causes confusion and a rapid decline in GCS.
Diagnosis: Pulse oximetry and arterial blood gases (ABG).
Management: Oxygen supplementation and addressing the underlying cause.

Toxic-Metabolic Encephalopathy

Pathophysiology: Metabolic disturbances from liver or renal failure lead to toxin accumulation affecting the brain.
Clinical Presentation: Patients may present with confusion, delirium, or coma.
Diagnosis: Blood tests, including liver and renal function, and ammonia levels.
Management: Treat the underlying metabolic disorder (e.g., lactulose for hepatic encephalopathy, dialysis for renal failure).

Sepsis

Pathophysiology: Systemic infection can cause encephalopathy by disrupting the blood-brain barrier and releasing inflammatory cytokines.
Clinical Presentation: Fever, confusion, and signs of shock.
Diagnosis: Blood cultures and other markers of infection.
Management: Antibiotics, fluid resuscitation, and source control.