Disorders of Consciousness: A Comprehensive Overview

Posted on Oct 23, 2024 in Psychology and Sociology

Disorders of Consciousness

I. Quantitative Alterations of Consciousness

These disorders involve a loss or diminution of consciousness, classified by severity:

  1. Drowsiness (Mild)

    Characterized by slowed responses, difficulty with attention, and decreased spontaneous activity. Orientation is preserved.

  2. Drowsiness (Moderate)

    Increased tendency to sleep, but easily aroused. May exhibit shiny or greasy skin.

  3. Sopor

    The individual remains asleep and only awakens to specific stimuli. May speak or perform simple actions.

  4. Coma

    A state of unconsciousness with loss of environmental awareness and ability to perform actions. Vegetative functions may be impaired. Coma is further divided into four stages:

    1. Surface Coma

      No response to painful stimuli, but muscle tone and reflexes may be present.

    2. Synergistic Flexor Coma

      Involuntary flexion movements, particularly in the upper extremities.

    3. Extensor Synergy Coma

      Internal rotation of upper extremities and extension of the head.

    4. Decisive Stage Coma

      Loss of all movement and muscle tone (hypotonia).

Causes of Coma

  1. Supratentorial Lesion (above the tentorium): Expansive lesions damaging the brainstem, leading to a progressive decline in brain function and consciousness. Examples include tumors, hematomas, or infections.

  2. Infratentorial Lesion (below the tentorium): Compression, injury, or destruction of the brainstem, such as hemorrhage or infarction.

  3. Diffuse/Multifocal/Metabolic Lesion: Multiple causes, including ischemia, hypoxia, hypoglycemia, organ failure (liver, renal, pulmonary, pancreatitis), endocrine disorders, toxins (barbiturates, depressants), acid-base imbalances, dehydration, temperature dysregulation (hypothermia or hyperthermia), nervous system infections, and primary neuronal diseases.

Differential Diagnosis of Coma

  • Akinetic Mutism: Patient does not speak but can direct their gaze.
  • Catatonic Stupor: Patient appears statue-like and unresponsive to stimuli.
  • Persistent Vegetative State: Normal vegetative function with sleep-wake cycles, but no awareness, following severe nervous system damage.
  • Psychogenic Unconsciousness: A hysterical state leading to unconsciousness.
  • Brain Death: Irreparable brain damage characterized by apnea, normal cardiac activity, absence of brainstem reflexes, dilated pupils, flat EEG, and no cerebral blood flow.

II. Qualitative Alterations of Consciousness

  1. Acute Delirium

    Associated with febrile illness (e.g., typhoid), agitation, fever, dehydration, visual hallucinations, and severe nervous system compromise. The patient is confused.

  2. Twilight State

    Consciousness is fixated on a single object, with all other stimuli ignored.

Organic Memory Disorders

Memory is the central nervous system’s ability to fix, store, and recall events, facts, and skills. It involves three levels: perception and encoding, retention and development (storage), and evocation and forgetting. Key brain structures include the hippocampus, temporal lobes, mammillary bodies, and dorsomedial nucleus of the thalamus.

Dissociations of Memory

  1. Memory and Intelligence

    No direct correlation exists between memory and intelligence.

  2. Episodic and Procedural Memory

    Episodic memory involves recalling personal experiences. Semantic memory involves recalling general knowledge.

  3. Short-Term, Medium-Term, and Long-Term Memory

    Categorization based on the duration of information retention.

  4. Retrograde and Anterograde Amnesia

    Retrograde amnesia involves forgetting past events. Anterograde amnesia involves difficulty forming new memories.

  5. Verbal and Nonverbal Memory

    Verbal memory involves language. Nonverbal memory involves visuospatial information.

Cortical Amnesias

Affect both episodic and procedural memory. Aphasia can be considered a procedural amnesia of language.

Epilepsy

A paroxysmal disorder of the central nervous system characterized by excessive neuronal discharge, leading to impaired consciousness, convulsions, and/or sensory disturbances.

Causes of Epilepsy

  1. Primary Epilepsy

    Cause is unknown, possibly genetic or biochemical.

  2. Secondary Epilepsy

    Known causes, such as vascular malformations, tumors, fractures, metabolic diseases, or hypoxia.

I. Generalized Epilepsy

Brain discharge is symmetrically distributed. Types include:

  1. Tonic-Clonic Seizures (Grand Mal)

    Involves muscle spasms (tonic) and rhythmic shaking (clonic).

  2. Lennox-Gastaut Syndrome

  3. Infantile Spasms

    Full-body contractions.

  4. Atonic Seizures

    Sudden loss of consciousness and muscle tone.

Stages of Generalized Seizures

  1. Tonic Phase

    Muscle spasms, dilated pupils, cyanosis (1-2 seconds).

  2. Clonic Phase

    Seizures, tachycardia, salivation, loss of sphincter control (30 seconds to 1 minute).

  3. Final Phase

    Muscular hypotonia, rattling breathing.

  4. Post-Ictal Phase

    Confusion, headache, drowsiness.

II. Partial Epilepsy

Neuronal firing is localized. Types include:

  1. Elementary/Simple Partial Seizures (No cognitive impairment)

    • Motor (Jacksonian or not): Tonic-clonic movements of a limb or multiple limbs.
    • Versive: Head turning.
    • Postural: Semi-flexed posture.
    • Phonatory: Momentary speech inhibition.

  2. Sensory/Somatosensory Partial Seizures

    • Visual, auditory, olfactory, gustatory, or vertiginous sensations.

  3. Autonomic Partial Seizures

    Sweating, paleness, stomach aches.

  1. Complex Partial Seizures (With cognitive impairment)

    • Dysphasic: Language impairment.
    • Dismnesic: Déjà vu or jamais vu.
    • Cognitive: Altered thinking.
    • Structured: Complex sensory or motor experiences.
    • Affective: Emotional changes.
    • Illusions/Hallucinations: Distorted perceptions.
    • Automatisms: Involuntary actions.

Epilepsy Treatment

  1. Address etiological factors and triggers.
  2. Mental and physical hygiene, psychotherapy.
  3. Antiepileptic drugs.
  4. Surgical treatment.

Neuropsychological Disorders: Agnosia and Apraxia

Agnosia

Impaired recognition of stimuli.

  • Visual Agnosia: Inability to recognize objects by sight.
  • Simultagnosia: Inability to perceive a whole object, only parts.
  • Prosopagnosia: Inability to recognize faces.
  • Color Agnosia: Inability to recognize colors.
  • Agnosia of Graphic Symbols (Agnostic Alexia): Inability to recognize letters.
  • Auditory Agnosia: Inability to recognize sounds.
  • Tactile Agnosia (Astereognosia): Inability to recognize objects by touch.
  • Somatoagnosia: Impaired body awareness in space.
  • Anosognosia: Lack of awareness of illness.
  • Digital Agnosia: Inability to identify fingers.

Apraxia

Loss of ability to perform learned motor acts.

  • Ideomotor Apraxia: Inability to perform simple gestures.
  • Ideational Apraxia: Inability to perform sequences of actions.
  • Constructive Apraxia: Inability to construct objects.
  • Dressing Apraxia: Inability to dress oneself.

Agraphia

Impaired writing ability.

Alexia

Impaired reading ability.

Dysarthria

Disturbance of muscular control of speech.