Etiology

Causes

Typical manifestations

Vascular

Subarachnoid or intracranial hemorrhage

Sudden onset, headache, vomiting, focal neurologic signs, signs suggestive of meningitis

Extensive stroke affecting bilateral cerebral hemispheres or brainstem

Sudden onset, focal neurologic signs, progressive clinical deterioration

Trauma

Direct brain injury or accumulating subdural hematoma

History of trauma, lacerations or other signs of head trauma, bleeding from ears or CSF leakage from nose or ears

Increased intracranial pressure

Brain tumor or abscess, subdural hematoma

History of escalating headache, progressive impairment of mental status, papilledema, focal neurologic signs

Inflammatory

Meningitis

History of headache and fever, subacute course, signs suggestive of meningitis

Encephalitis

As above plus signs of disseminated encephalopathy, seizures, involuntary movements

Metabolic

Hypoglycemia

Hyperhidrosis, dilated pupils, seizures, hyporeflexia, Babinski sign, sometimes focal neurologic signs

Hyperglycemia

Hyperventilation, Kussmaul breathing

Uremia

Progressive apathy, progressive obtundation, tremor, seizures

Liver disease

Coma preceded by memory impairment, confusion, and somnolence with subsequent development of pyramidal, extrapyramidal, and cerebellar signs and low frequency tremor

Hypercalcemia

Signs of hypercalcemia

Hyponatremia

Cerebral edema caused by changes in CSF and cell tonicity, can also be provoked by overly rapid correction in patient with chronic derangement

Hypernatremia

Signs of hypernatremia

Myxedema

History of hypothyroidism, gradual deterioration over weeks, common hypercapnia

Epilepsy

Epilepsy

Sudden abnormalities in behavior or mental status, seizures, sometimes extremity paresis

Hypoxia

Cardiac and respiratory arrest

Sudden onset, decortication or decerebration, myoclonus, epileptic seizures

Hypercapnia

Carbon dioxide retention in patients with respiratory insufficiency

Gradual deterioration of mental status, prior headache, shallow respiration, conjunctival injection

Extreme body temperatures

Hypothermia

Signs of hypothermia

Hyperthermia

Signs of hyperthermia

Toxins

Toxic alcohols, ethanol

Signs of alcohol intoxication

Anticholinergics, sedative hypnotics, antipsychotics, opioids, carbon monoxide poisoning

Signs of poisoning and intoxication

Psychiatric

Catatonia, pseudocoma

History of psychiatric diagnosis and deterioration, normal cold caloric testing