Author:
David W.Schoenfeld
Christopher J.Shestak
Description
- Dysfunction in either the reticular activating system in the upper brainstem or a large area of 1 or both cerebral hemispheres
- Definitions:
- Confusion: A behavioral state of reduced mental clarity, coherence, comprehension, and reasoning
- Drowsiness: The patient cannot be easily aroused by touch or noise and cannot maintain alertness for prolonged periods of time
- Lethargy: Depressed mental status in which the patient may appear wakeful but has depressed awareness of self and environment globally; cannot be aroused to full function
- Stupor: The patient can be awakened only by vigorous stimuli, and an effort to avoid uncomfortable or aggravating stimulation is displayed
- Coma: The patient cannot be aroused by stimulation and no purposeful attempt is made to avoid painful stimuli
- Delirium: Acute onset of fluctuating cognition with impaired attention and consciousness, ranging from confusion to stupor
Etiology
- Hypoxic:
- Severe pulmonary disease
- Anemia
- Shock
- Intracardiac shunting (especially in pediatrics)
- Metabolic:
- Hypoglycemia; hyperglycemia
- Diabetic ketoacidosis
- Nonketotic hyperosmolar coma
- Hyponatremia; hypernatremia
- Hypocalcemia; hypercalcemia
- Hypomagnesemia; hypermagnesemia
- Hypophosphatemia
- Acidosis; alkalosis
- Dehydration
- Deficiency: Thiamine, folic acid, B12, niacin
- Hyperammonemia (hepatic encephalopathy)
- Uremia (renal failure)
- CO2 narcosis
- Toxicologic:
- Toxic alcohols
- Salicylates
- Sedatives and narcotics
- γ-Hydroxybutyrate (GHB)
- Anticonvulsants
- Psychotropics
- Isoniazid
- Heavy metals
- Carbon monoxide
- Cyanide
- Toxic plants (jimsonweed, mushrooms, etc.)
- Sympathomimetics
- Anticholinergic, cholinergic
- Antiemetics
- Antiparkinsonian medications
- Neuroleptic malignant syndrome
- Serotonin syndrome
- Malignant hyperthermia
- Withdrawal (especially alcohol, sedatives)
- Infectious:
- UTI (especially in elderly)
- Pneumonia
- Sepsis; bacteremia
- Meningitis, encephalitis, brain abscess
- Endocrine:
- Myxedema coma
- Thyrotoxicosis
- Hypothyroidism
- Addison disease
- Cushing disease
- Pheochromocytoma
- Hyperparathyroidism
- Environmental:
- Hypothermia
- Hyperthermia; heat stroke
- High-altitude cerebral edema
- Neuroleptic malignant syndrome
- Vascular:
- Hypertensive encephalopathy
- Cerebral vasculitis
- TTP, DIC, hyperviscosity
- MI
- Primary neurologic:
- Seizures, nonconvulsive status epilepticus, and postictal state
- Head trauma, concussion
- Diffuse axonal injury
- Structural brain lesions:
- Hemorrhage (subdural, epidural, subarachnoid, intraparenchymal)
- Infarction
- Tumors
- Demyelinating disorders
- Idiopathic intracranial hypertension (pseudotumor)
- HIV-related encephalopathy
- Autoimmune/inflammatory encephalitis
- Carcinoid meningitis
- Primary neuronal or glial disorders:
- Creutzfeldt-Jakob disease
- Marchiafava-Bignami disease
- Adrenoleukodystrophy
- Gliomatosis cerebri
- Progressive multifocal leukoencephalopathy
- Trauma; burns
- Porphyria
- Psychiatric
- Multifactorial (especially in elderly)
Signs and Symptoms
Confusion
- Difficulty in maintaining a coherent stream of thinking and mental performance:
- Remember to consider level of education, primary language, and possible learning disabilities
- Inattention:
- Inability to follow tasks, selectively focus on important pieces of information
- Memory deficit:
- Inability to recall any of the following:
- The date, inclusive of month, day, year, and day of week
- The precise place
- Items of universally known information
- Why the patient is in the hospital
- Address, telephone number, or Social Security number
- Impaired mental performance:
- Difficulty retaining 7 digits forward and 4 backward
- Difficulty naming ordinary objects
- Serial calculations: serial 7 subtraction test
- Disorganized and rambling language:
- May be mistaken for aphasia
- Fever:
- Infectious etiologies, drug toxicities, endocrine disorders, heat stroke
- Severe hypertension and bradycardia
- Cushing reflex suggests intracranial lesion
- Hypotension:
- Infectious, toxicologic etiologies, decreased cardiac output
- Eye movements:
- Ocular bobbing:
- Cyclical, brisk, conjugate, caudal jerks of the globes, followed by a slow return to midposition
- Seen in bilateral pontine damage, metabolic derangement, and brainstem compression
- Ocular dipping:
- Slow, cyclical, conjugate, downward movement of the eyes, followed by a rapid return to midposition
- Seen in diffuse cortical anoxic damage
- Pupil exam:
- Nearly all toxic and metabolic causes of coma leave the pupillary reflexes sluggish but bilaterally intact
- Focal findings (indicative of CNS process):
- Hemiparesis
- Hemianopsia
- Aphasia
- Myoclonus
- Convulsions
- Nuchal rigidity
- Asterixis:
- Arrhythmic flapping tremor (almost always bilateral)
- Seen in hepatic failure or severe renal failure
History
- Ask witnesses, family, pre-hospital personnel
- Baseline mental status
- Medical history (immunosuppressed, liver failure, depression, or chronic conditions)
- Recent events: Trauma, fever, illness
- Detailed medication list
- Substance abuse history
Physical Exam
- Vital signs
- Head: Signs of trauma, pupils
- Fundoscopic exam: Hemorrhage, papilledema
- Neck: Rigidity, bruits, thyroid enlargement
- Heart and lungs
- Abdomen: Organomegaly, ascites
- Extremities: Cyanosis
- Skin: Diaphoretic/dry, rash, petechiae, ecchymoses, splinter hemorrhages, needle tracks
- Neurologic exam
- Mental status exam
Diagnostic Tests & Interpretation
Lab
- Dextrostix and glucose
- CBC
- Electrolytes (including Ca, Mg, P)
- BUN, creatinine
- Toxicologic screen (including toxic alcohols)
- ECG
- Urinalysis
- Blood and urine cultures (suspected infection)
- PT, PTT (anticoagulated, liver failure patients)
- Consider LFTs, thyroid function tests, ammonia, serum osmolarity, arterial blood gas
- Consider B12, folic acid, RPR, urine porphobilinogen, heavy metal screening
Imaging
- Head CT scan:
- Noncontrast only to rule out hemorrhage and mass effect
- Chest radiograph: To diagnose pneumonia
- MRI (if available):
- Indicated when suspicious of ischemic stroke or other CNS abnormality
- May be deferred when admitting the patient as part of the inpatient workup
Diagnostic Procedures/Surgery
- Lumbar puncture (LP):
- Indicated when the etiology remains unclear after labs and CT scan
- Empiric antibiotics should be given before LP in patients with suspected meningitis
- EEG (inpatient): For suspected seizure, nonconvulsive status epilepticus
- Caloric stimulation of the vestibular apparatus to assess unresponsive patients
Differential Diagnosis
- Locked-in syndrome:
- Rare disorder caused by damage to the corticospinal, corticopontine, and corticobulbar tracts resulting in quadriplegia and mutism with preservation of consciousness
- Communication may be established through eye movements (maintain vertical eye movements)
- Psychogenic unresponsiveness:
- Conversion reactions
- Catatonia
- Malingering
- Akinetic mutism (abulic state)
- Dementia:
- Multiple progressive cognitive deficits
- Attention is preserved in the early stages.
Prehospital
- Airway management if loss of airway patency or concern for inability to protect airway
- IV access, supplemental oxygen, cardiac monitor
- Spine immobilization if possibility of trauma
- “Coma cocktail”:
- Look for signs of an underlying cause:
- Medications, medic alert bracelets
- Document a basic neurologic exam, GCS, pupils, extremity movements
- Gross signs of trauma
- CONTROVERSIES:
- Empirical dextrose should not be withheld or delayed if Dextrostix is not available
- Glucose can be safely administered before thiamine
Initial Stabilization/Therapy
ED Treatment/Procedures
- Consider empiric use of antibiotics for altered mental status of undetermined etiology, particularly if febrile:
- Empiric treatment if a toxic ingestion is suspected
- Correct body temperature
- Specific therapy directed at underlying cause
Medication
- Acyclovir: 10 mg/kg/dose q8h
- Ceftriaxone: 2 g (peds: 100 mg/kg loading dose, followed by 100 mg/kg/d div q12-24h) IV q12h
- Dextrose: 1-2 mL/kg of D50W (peds: 2-4 mL/kg D25W) IV
- Diazepam: 0.1-0.3 mg/kg slow IV (max 10 mg/dose) q10-q15min × 3 doses
- Lorazepam: 0.05-0.1 mg/kg IV (max. 4 mg/dose q10-q15min)
- Mannitol: 0.5-1 g/kg IV
- Naloxone: 0.4-2 mg IV/IM/SC, 2-4 mg IN, 0.8-5 mg ET
- Thiamine: 100 mg IM or in 1,000 mL of IV fluid wide open
- Vancomycin: 15-20 mg/kg/dose q8-12h (max 2 g/dose)
Disposition
Admission Criteria
All patients with acute and persistent changes in mental status require admission
Discharge Criteria
- Treated hypoglycemia related to insulin therapy with resolved symptoms
- Chronic altered mental status (e.g., dementia) without change from baseline
- Acute drug intoxication with return of patient's mental status to baseline, and drug has no potential for delayed toxicity
Follow-up Recommendations
Primary care follow-up to manage etiology that led to altered mental status (e.g., adjust medication dosing, drug abuse treatment referral)