Metabolic Coma and Altered Mental Status

Vocabulary flashcards covering the pathophysiology, clinical manifestations, diagnostics, and management of metabolic coma, CNS infections, encephalopathies, toxidromes, and altered levels of consciousness.

Metabolic Coma

A state of global brain dysfunction caused by systemic disease rather than a primary structural brain lesion, typically affecting both cerebral hemispheres and potentially reversible with rapid treatment.

VITAMINS Mnemonic

A diagnostic memory aid for causes of metabolic coma: Vascular, Infection, Trauma, Autoimmune/Alcohol, Metabolic, Intoxication, Neoplasm, and Seizure/Stroke.

Central Nervous System Infection Classifications

The clinical categorizations of CNS infections: meningitis (pathogens infect meningeal layers), meningoencephalitis (infection starts in meninges and spreads to brain parenchyma), encephalitis (pathogens infect brain parenchyma), and brain abscess (pathogens wall themselves off within the brain).

Meningitis

Inflammation of the arachnoid and pia mater layers of the brain and spinal column, most often caused by bacteria or viruses entering the cerebrospinal fluid across the blood-brain barrier or via direct entry.

Bacterial Meningitis Classic Manifestations

The hallmark clinical presentation of acute bacterial meningeal inflammation, consisting of fever, severe headache, nuchal rigidity, photophobia, altered mental status, and nausea or vomiting.

CSF Findings: Bacterial vs. Viral Meningitis

Diagnostic cerebrospinal fluid differences: bacterial meningitis presents with elevated WBC, elevated protein, low glucose, and positive cultures; viral meningitis presents with elevated lymphocytes, mild protein elevation, normal glucose, and negative bacterial cultures.

Encephalitis

Inflammation of brain tissue and often the meninges caused by viruses, bacteria, fungi, or parasites, resulting in axonal demyelination, edema, vascular compression, and elevated intracranial pressure.

Acute or Subacute Encephalopathy

Cognitive impairment lasting $\le 3\text{ months}$ resulting from primary neurologic or non-neurologic causes (toxins, infections, metabolic derangements, nutritional deficiencies), spanning from mild confusion to a comatose state.

Hepatic Encephalopathy

A life-threatening neuropsychiatric abnormality resulting from liver dysfunction and impaired metabolism of toxic substances, characterized by elevated serum ammonia, sleep disturbances (insomnia/hypersomnia), mood changes, asterixis, confusion, and progression to coma.

Asterixis

A non-rhythmic flapping tremor of the hands, classic for hepatic encephalopathy caused by hyperammonemia and metabolic brain dysfunction.

Uremic Encephalopathy

A metabolic disorder featuring progressive neurological dysfunction (cognitive impairment, lethargy, seizures, and coma) due to the accumulation of uremic toxins in acute kidney injury, chronic kidney disease, or underdialysis.

Sepsis-Associated Encephalopathy (SAE)

Diffuse cerebral dysfunction triggered by systemic infection that progresses through sickness behavior, delirium, and coma or sedation, damaging structures such as the limbic system, frontal cortex, hippocampus, and brainstem.

Arbovirus

An arthropod-borne virus transmitted to humans by insect vectors such as mosquitoes or ticks; examples include West Nile, Zika, Chikungunya, Eastern equine encephalitis, Powassan virus, and Lyme disease.

Erythema Migrans

The hallmark expanding erythematous skin lesion seen in Lyme disease, frequently presenting as a circular or 'bull\'s-eye' pattern appearing $> 14\text{ days}$ post-tick bite that is typically painless and non-pruritic.

Wernicke's Encephalopathy

An acute neurological complication associated with chronic alcohol misuse and thiamine deficiency, classically presenting with confusion, ataxia, and ophthalmoplegia.

Korsakoff's Psychosis

A chronic, often irreversible neuropsychiatric condition resulting from alcohol-related thiamine deficiency, marked by severe anterograde memory impairment and confabulation.

Delirium Tremens (DTs)

A life-threatening emergency during severe alcohol withdrawal characterized by intense agitation, tremors, nausea, altered mental status, visual or auditory hallucinations, seizures, tachycardia, hypertension, and fever.

CIWA-Ar

A standardized clinical assessment scale for alcohol withdrawal: scores $\le 8$ indicate absent or mild withdrawal needing monitoring; $9\text{--}15$ indicate moderate withdrawal needing medication to prevent progression; $\ge 15$ indicate severe withdrawal where medication is strongly indicated.

Acetaminophen Overdose: Stage 1

The initial $0\text{ to }24\text{ hours}$ following toxic ingestion, during which the individual may be asymptomatic or display mild non-specific symptoms like nausea, vomiting, diaphoresis, and anorexia.

Acetaminophen Overdose: Stage 2

The phase occurring $24\text{ to }72\text{ hours}$ after toxic ingestion, during which early symptoms fade, abdominal pain and vomiting appear, and serum transaminases indicate hepatic injury.

Acetaminophen Overdose: Stage 3

The critical toxic phase at $3\text{ to }4\text{ days}$ post-ingestion, marked by recurrent severe nausea, vomiting, jaundice, coagulopathy, liver failure, and possible acute renal failure.

Acetaminophen Overdose: Stage 4

The phase beginning at $5\text{ days and beyond}$ post-ingestion, in which the patient either initiates clinical recovery or succumbs to complete liver failure and multiorgan failure.

N-acetylcysteine (NAC)

The specific antidote (also branded as Mucomyst) administered alongside activated charcoal and supportive therapy to prevent and treat hepatotoxicity from acetaminophen overdose.

AEIOU TIPS Mnemonic

A systematic clinical mnemonic for identifying causes of altered mental status: Alcohol, Epilepsy, Insulin, Overdose, Uraemia, Trauma, Infection, Psychiatric condition, and Stroke/Shock.

Persistent Vegetative State

A chronic condition characterized by intermittent wakefulness without self-awareness or environmental awareness, preserved brainstem autonomic functions, lack of purposeful responses to stimuli, and absence of language comprehension.

Coma vs. Vegetative State

In a coma, the eyes remain closed and the patient is completely unconscious with no response; in a vegetative state, the patient's eyes can open and involuntary responses like blinking occur, giving an appearance of wakefulness without actual awareness.

Brain Death Declaration Protocol

A 4-step formal protocol to confirm death: 1) identify an irreversible cause while ruling out confounding factors (drugs, hypothermia, metabolic issues), 2) verify absence of pain response, brainstem reflexes, and spontaneous respiration via apnea testing, 3) use confirmatory scans if needed, and 4) conduct independent evaluations by two physicians.