Neurology: Coma and Stupor

Stupor and Coma

• Stupor and coma are two types of altered consciousness that affect arousal.
• Consciousness is defined as a state of awareness of self and surroundings.
• Alterations in consciousness can be categorized into two types: one affecting arousal and the other affecting cognitive and affective mental function.

Definitions

• Delirium is a disturbance in attention and awareness that can occur with or without a reduced level of consciousness.
• Delirium is classified as a disorder of arousal or mental function depending on the context.
• Coma is a state of complete unresponsiveness to arousal.

Conditions that May Mimic Coma

• Locked-in syndrome: a condition where patients are alert and aware but quadriplegic and able to move only their eyes.
• Persistent vegetative state: a condition where patients are awake but unaware of their surroundings and have no purposeful behaviors.
• Abulia: a severe apathy in which patients have blunted feeling, drive, mentation, and behavior.
• Catatonia: a state of muteness with decreased motor activity.
• Pseudocoma: a condition where patients feign coma.

Approach to the Patient in Coma

• The initial approach to a patient in coma is to treat the condition as a life-threatening emergency until vital functions are stabilized.
• Urgent steps may be necessary to avoid or minimize permanent brain damage.
• A basic understanding of the mechanisms leading to impaired arousal is necessary to develop a diagnostic and therapeutic routine.

Common Causes of Coma

• Diffuse and metabolic brain dysfunction (more than half of all cases)
• Drug poisoning (almost half of diffuse and metabolic brain dysfunction cases)
• Supratentorial mass lesions (101 cases in Plum and Posner's study)
• Subtentorial lesions (65 cases in Plum and Posner's study)
• Psychiatric coma (8 cases in Plum and Posner's study)

Initial Examination

• Check general appearance, blood pressure, pulse, temperature, respiratory rate, and breath sounds.

• Stabilize the neck in cases of trauma.

• Protect the airway and place an intravenous line.

• Consider a CT scan of the abdomen or peritoneal lavage in cases of trauma.

• Hypotension, hypertension, bradycardia, and signs of cerebral herniation require immediate therapeutic intervention.

• Hyperthermia or meningismus prompts consideration of urgent lumbar puncture.

• Examination of the fundus of the eye for papilledema and a CT scan of the brain should be performed before lumbar puncture.

• Infection at the site of lumbar puncture, papilledema, decerebrate posturing, and thrombocytopenia and other bleeding diathesis are contraindications to lumbar puncture.### Coma and Stupor

• Coma can be a predictable progression of an underlying illness, an unpredictable event in a patient with known medical conditions, or a sudden event in a patient with unknown medical history.

Initial Examination and Therapy

• A rapid initial assessment is essential to ensure the patient's medical and neurological stability before conducting a more detailed investigation.
• Urgent and sometimes empirical therapy is necessary to prevent further brain damage.
• Empirical use of supplemental oxygen, intravenous thiamine, and intravenous 50% dextrose in water may be necessary.
• A baseline serum glucose level should be obtained before glucose administration.

Acute Bacterial Meningitis

• When acute bacterial meningitis is strongly suspected, antibiotics and adjunctive corticosteroids should be administered within 1 hour of hospital admission.
• Blood cultures and throat swabs should be obtained before antibiotic administration.
• Corticosteroid administration should be avoided in the presence of septic shock.

Lumbar Puncture

• Lumbar puncture should be performed with caution, as it poses a risk of herniation in patients with increased intracerebral pressure.
• Multiplex nucleic acid amplification tests may be helpful in diagnosing CNS infections.
• Measurements of prothrombin time, partial thromboplastin time, and platelet count should precede lumbar puncture in cases of coagulation abnormality or thrombocytopenia.

Causes of Coma

• Toxins, metabolic disorders, and infections are common causes of coma (Table 5.4).
• Structural causes include supratentorial and infratentorial lesions, and asymmetrical presentations.

Common Presentations

• Coma may present as a sudden, unexpected event, or as a predictable progression of an underlying illness.
• Comatose patients may have a history of psychiatric disease, previous similar episodes, or unusual responses to stress.
• Family members or friends may be able to provide valuable information about the patient's medical history and circumstances surrounding the coma.

General Examination

• A systematic, detailed general examination is essential in the approach to the comatose patient.
• Blood pressure, pulse, respiratory rate, and temperature should be evaluated.
• Special care must be taken not to be misled by an apparently predictable progression of an underlying illness.

Blood Pressure Evaluation

• Hypotension may result in coma if the mean arterial pressure decreases to less than 60 mm Hg.
• Causes of hypotension include hypovolemia, massive external or internal hemorrhage, myocardial infarction, cardiac tamponade, and intoxication with alcohol or other drugs.

Heart Rate

• Bradycardia can result from the Kocher-Cushing reflex, myocardial conduction blocks, certain poisonings, and effects of drugs such as beta-blockers.
• Tachycardia can result from hypovolemia, hyperthyroidism, fever, anemia, and certain toxins and drugs.

Respiration

• Decreased respiratory rate can result from metabolic or toxic causes, such as carbon dioxide narcosis or drug overdose.
• Increased respiratory rate can result from hypoxia, hypercapnia, acidosis, hyperthermia, hepatic disease, toxins or drugs, sepsis, and pulmonary embolism.

Head Trauma

• Laceration or edema of the scalp is indicative of head trauma.
• Raccoon eyes and Battle sign are indicative of basilar skull fracture.### Rhythm in a Comatose Patient
• Neck stiffness may be a sign of infectious or carcinomatous meningitis, subarachnoid hemorrhage, or central or tonsillar herniation.
• Absence of neck stiffness does not rule out coma from any cause.

Temperature

• Core temperature is best measured with a rectal probe in a comatose patient.
• Pyrexia is often a sign of infection.
• Absence of elevated temperature does not rule out infection.
• Pure neurogenic hyperthermia is rare and usually due to subarachnoid hemorrhage or diencephalic (hypothalamus) lesions.

Eye Examination

• Examination of the eyes includes observation of the cornea, conjunctiva, sclera, iris, lens, and eyelids.
• Edema of the conjunctiva and eyelids may occur in congestive heart failure and nephrotic syndrome.
• Congestion and inflammation of the conjunctiva may occur in the comatose patient from exposure.
• Enophthalmos indicates dehydration.
• Scleral icterus is seen with liver disease.

Head and Neck Examination

• Palpation for depressed skull fractures and edema should be attempted.
• Signs of trauma should be carefully examined.
• Infections of the middle ear, mastoid, and paranasal sinuses are the most common sources of underlying infection in brain abscess.

General Appearance

• The general appearance of the patient may provide further clues to the diagnosis.
• Torn or disheveled clothing may indicate prior assault.
• Vomiting may be a sign of increased ICP, drug overdose, or metabolic or other toxic cause.
• Urinary or fecal incontinence suggests an epileptic seizure or may result from a generalized autonomic discharge.

Integument Examination

• Systematic examination of the integument includes inspection of the skin, nails, and mucous membranes.
• Hot, dry skin is a feature of heat stroke.
• Sweaty skin is seen with hypotension or hypoglycemia.
• Drugs may cause macular-papular, vesicular, or petechial-purpuric rashes or bullous skin lesions.

Cardiac Examination

• Cardiac auscultation will confirm the presence of arrhythmias such as atrial fibrillation.
• Changing mitral murmurs are heard with atrial myxomas and papillary muscle ischemia.

Abdominal Examination

• Abdominal examination may reveal abnormal bowel sounds, organomegaly, masses, and ascites.
• Bowel sounds are absent in an acute abdominal condition, as well as with anticholinergic poisoning.
• Hyperactive bowel sounds may be a consequence of increased gastrointestinal motility.

Neurological Examination

• The neurological examination of a comatose patient serves three purposes: to aid in determining the cause of coma, to provide a baseline, and to help determine the prognosis.
• The examination should include the state of consciousness, respiratory pattern, pupillary size and response to light, spontaneous and reflex eye movements, and skeletal muscle motor response.

Glasgow Coma Scale

• The Glasgow Coma Scale is used to assess the initial severity of traumatic brain injury.
• The scale assesses three separate aspects of a patient's behavior: the stimulus required to induce eye opening, the best motor response, and the best verbal response.
• Degrees of increasing dysfunction are scored.

Respiratory Patterns

• Cheyne-Stokes respiration is a respiratory pattern that oscillates between hyperventilation and hypoventilation.
• It was first described by Cheyne in 1818.
• Short-cycle periodic breathing is a respiratory pattern with a shorter cycle than Cheyne-Stokes respiration, with one or two waxing breaths, followed by two to four rapid breaths, then one or two waning breaths.
• It is seen with increased ICP, lower pontine lesions, or expanding lesions in the posterior fossa.

Brainstem Mechanisms

• Respiratory rhythm generation is regulated by a brainstem mechanism located between the midpons and cervical medullary junction.
• Forebrain influences also play a role in regulating metabolic needs and behavioral needs such as speech production.

Consciousness

• Consciousness is a state of awareness of self and surroundings.
• Alterations in consciousness can be conceptualized into two types, affecting arousal and cognition.
• These states are dynamic and may change with time.

Coma

• Coma is a state of altered consciousness characterized by a lack of awareness of self and surroundings.
• It is a dynamic state that may change with time.
• Differentiating toxic-metabolic coma from structural coma is important for diagnosis and treatment.

Neurological Examination

• A thorough neurological examination is necessary to determine the level of consciousness and identify potential structural lesions.
• The examination should include a rapid initial examination, history, general examination, and neurological examination.

Respiratory Examination

• Normal breathing is quiet and unlabored.
• The presence of any respiratory noise implies airway obstruction, which must be dealt with immediately to prevent hypoxia.

Glasgow Coma Scale

• The Glasgow Coma Scale is a tool used to assess the level of consciousness.
• It consists of three components: best motor response, verbal response, and eye opening.

Lumbar Puncture

• Lumbar puncture is a diagnostic tool used to collect cerebrospinal fluid.
• Contraindications to lumbar puncture include infection at the site of the lumbar puncture, papilledema, decerebrate posturing, and thrombocytopenia and other bleeding diathesis.
• In cases of suspected acute bacterial meningitis, antibiotics and adjunctive corticosteroids should be administered within 1 hour of hospital admission, even if cerebrospinal fluid collection cannot be obtained in a timely fashion.

Pupil Size and Reactivity

• Pupil size in a comatose patient depends on the level of illumination and the state of autonomic innervation.
• Thalamic lesions cause small, reactive pupils (diencephalic pupils).
• Hypothalamic lesions or lesions along the sympathetic pathway result in Horner syndrome.
• Midbrain lesions produce three types of pupillary abnormalities, depending on the location of the lesion.

Pupillary Asymmetry

• Asymmetry in pupillary size or reactivity is important, even if minor.
• Asymmetry may be due to dilation (mydriasis) of one pupil or contraction (miosis) of the other.
• Pupillary reactivity to light and associated neurological signs can help differentiate the causes.

Eye Deviation

• Spontaneous eye deviation may be conjugate or dysconjugate.
• Conjugate lateral eye deviation usually indicates an ipsilateral lesion in the frontal eye fields.
• Dysconjugate eye deviation may indicate a lesion in the brainstem or elsewhere in the pathway.

Oculocephalic Reflex

• The oculocephalic reflex is used to assess brainstem function.
• Normal response: eyes move in the opposite direction of the head movement.
• Abnormal responses: no movement, one eye moves, or bilateral limitation of upgaze.

Glasgow Coma Scale

• The Glasgow Coma Scale assesses the severity of coma based on motor response, verbal response, and eye opening.
• Motor response: obeys, localizes, withdraws, flexion, extensor response, or nil.
• Verbal response: oriented, confused, inappropriate, or nil.

Cardiac Examination

• Cardiac auscultation can confirm the presence of arrhythmias, such as atrial fibrillation.
• Changing mitral murmurs may indicate atrial myxomas or papillary muscle ischemia.
• Constant murmurs may indicate valvular heart disease.

Abdominal Examination

• Abdominal examination may reveal abnormal bowel sounds, organomegaly, masses, or ascites.
• Bowel sounds are absent in acute abdominal conditions or anticholinergic poisoning.

Brainstem Function

• Cold water caloric testing can help diagnose brainstem lesions.
• Ipsilateral paralysis indicates a probable brainstem lesion.
• Decerebrate posturing: bilateral extensor posture, with extension of the lower extremities and adduction and internal rotation of the shoulders.
• Decorticate posturing: bilateral flexion at the elbows and wrists, with shoulder adduction and extension of the lower extremities.