Disorders of Consciousness

DISORDERS OF CONSCIOUSNESS

Rebecca John MBBS Graduate, Kannur Medical College, Kerala, India  Introduction  Pathophysiology  Etiology  Spectrum of consciousness  Definitions  Impairment of conscious states  Management Consciousness

 State of full awareness of the self and one’s relationship to the environment.

 Two elements

 Arousal – wakefulness/alertness (Ascending reticular activating system at pons, midbrain, thalamus, hypothalamus)

 Content-affective and cognitive functions such as attention, memory, motivation and executive function ( higher level structures of cerebral cortex and connections to subcortical white matter ) Pathophysiology Integral Consciousness requires an intact - 1) Ascending reticular activating system, 2) Cerebral cortex, 3) Healthy projections between the two systems. • Begins in the lower brainstem and extends upward through pons, midbrain, thalamus • Finally project throughout cerebral cortex into two pathways a) through subthalamus b) through thalamus The state of wakefulness is mediated by neurons of the ascending reticular activating system(ARAS). • Neural pathways from these locations project throughout the cortex , which is responsible for awareness. Loss of consciousness will result if • The function of ARAS neurons compromised or • Both cerebral hemisphere are sufficiently affected by disease. Proper function of ARAS and both cerebral hemisphere depends on: • Presence of substrate for energy production • Adequate blood flow • Absence of abnormal metabolic wastes or toxins • Normal body temperature • Absence of abnormal neuronal excitation or irritation from seizure activity • Absence of CNS infections • Normal intracranial pressure Etiologies of impaired consciousne ss Infectious Inflammatory Structural Metabolic Toxins Psychogenic Heavy Hyper/hyoglyc metal Bacterial emia Catatonia meningitis Demyelinatio poisonin n g Rikettsial Hyponatremia Conversion infection Disorder Vasculitis Alcohol Hypercalcemia Viral Sepsis Malingering encephalitis associated Hyperbilirubine Carbon encephalopathy mia Monoxide Acute disseminated Acute uremia encephalopmyel itis Supratentorial Infratentorial

Brainste Traumatic Vascular Focal Neoplastic Cerebellum m

Abscess Pontine Hematoma Concussion Anoxic- hemorrhage Ischemic Brain encephalopath mets y Cerebritis Abscess

Epidural/int Basilar racerebral Multiple artery Tumor hematoma cortical thrombosis infarctions Lymphoma

Diffuse axonal Bilateral Central injury Thalamic pontine infarction myelinosi s

Definitions

• Sleep - Biologically active state with identifiable behavioral and EEG stages, with appropriate stimulus intensity and duration sleeping person can be aroused to a normal state of consciousness.

• IRS - Unpredictable, transient and spontaneous unresponsiveness lasting from hours to days, with a frequency of three to seven attacks per year, in the absence of readily discernible toxic, metabolic or structural causes.

• Catatonia is marked by a significant decrease in someone's reactivity to their environment. This can involve stupor, mutism, negativism, or motor rigidity, and even purposeless excitement.

• Non-Convulsive Status Epilepticus (NCSE) is a persistent change in the level of consciousness, behavior, autonomic function, and sensorium from baseline associated with continuous epileptiform EEG changes, but without major motor signs Impairment of consciousness states

Impairment of consciousness Impairment of consciousness Impairment of consciousness along the continuum of with activated mental state with reduced mental state coma–vegetative state– minimally conscious state

Delirium : Activated mental state that may include disorientation, irritability, Drowsiness fearful- responses, and sensory misperception.

Delusion : Incorrect thoughts or beliefs that do not change when challenged by Obtundation contradictory evidence or logical reason.

Illusion : Misinterpretation of Stupor actual sensory stimuli.

Hallucination : Perception of sensory input that are not present. Impairment of consciousness with reduced mental state

• Drowsiness

• Obtundation arousal is present to stimuli • Stupor

State Stimulus needed for arousal Drowsiness Verbal and light touch Obtundation Deep touch Stupor Vigorous, painful, or noxious stimulation Vegetative state • Complete unawareness of self & environment accompanied by sleep-wake cycles with complete/partial preservation of hypothalamic and brainstem autonomic function. • Persistent Vegetative state - > 1month • Permanent Vegetative state (Poor prognosis) - > 3 months after non-traumatic injury, >12 months after traumatic injury Minimally conscious state

• Severely alterered consciousness, demonstrates minimal evidence of self / environmental awareness. • Neurologic recovery-better. • Life expectancy- longer than vegetative state. Locked-In Syndrome

• Retain consciousness & cognition but unable to move or communicate because of paralysis. • Involvement – Descending corticospinal & corticobulbar pathways at or below Pons/ Peripheral nervous system. • Communication – using eye movements. Akinetic Mutism

• Akinetic mutism is “a state of limited responsiveness to the environment in the absence of gross alteration of sensorimotor mechanisms operating at a more peripheral level.” Neither paralysis nor coma accounts for the symptoms. Patients may open their eyes and seem alert, and brief movement, speech, or even agitation may follow powerful stimuli; however, patients are otherwise “indifferent, detached, frozen, and apathetic.”

• Pathologically slowed or nearly absent bodily movement accompanied by loss of speech. • Wakefulness and Self awareness - Preserved. • Mental function- Reduced. • Area Involved – damage to paramedian mesencephalon, basal diencephalon, inferior frontal lobes. Coma

• State of deep, unarousable, sustained pathologic unconsciousness with the eyes closed that results from dysfunction of the ascending reticular-activating system in the brainstem or in both cerebral hemispheres. • Patients in coma lack both wakefulness and awareness.

Brain Death

• Brain death is defined as the irreversible loss of all functions of the brain, including the brainstem.

• The three essential findings in brain death are coma, absence of brainstem reflexes, and apnoea test.

Ancillary neurodiagnostic studies

• Electroencephalography- Absence cerebral activity over 30 min recording. • Radionuclide imaging – Absence of radionuclide detection in brain parenchyma and large vessels. • Cerebral angiography – Absence of intracranial filling of large cerebral arteries & branches. • Transcranial Doppler ultrasound- loss of diastolic flow, systolic flow,flow reversal. Condition Self- Pain and Sleep– Motor Function Respiratory Awareness Suffering Wake Function Cycles Coma Absent No Absent No purposeful Variably movement depressed Vegetative Absent No Intact No purposeful Normal State movement Minimaly Very Yes Intact Severe limitation Variably conscious limited of movement depressed State Locked-in- Present Yes Intact Quadriplegia, Normal to syndrome Eye movements variably + depressed. Brain Absent No Absent None Absent Death Management • Rapid assessment and stabilization – ABCDE • Assess vital signs Temp:

 Fever – Sepsis, pneumonia, meningitis, encephalitis, intracranial abscess, empyema.

 Hypothermia - Sepsis, shock, alcohol, barbiturate poisoning, hypoglycemia.  Very high fever and dry skin – Heat stroke. HR:

 Bradycardia -↑ ICT, myocardial injury due to hypoxia, sepsis  Tachycardia - Shock, Infections, Fever, Heart failure  Irregular –Arrhythmia

RR:  Bradypnea/ Apnea - Drug intoxication, septicemia

 Tachypnea - Metabolic Acidosis, Pneumonia, Asthma, Pulmonary embolism, Brainstem lesion.

BP:  HTN - ↑ICP or stroke, HTN encephalopathy

 Hypotension -Shock, sepsis, myocardial injury / failure, drug ingestion , adrenal insufficiency. Clues to etiology of coma in general examination

Look for if present ,think of Pallor Cerebral malaria, intracranial bleed, hemolytic uremic syndrome Icterus Hepatic encephalopathy, leptospirosis, complicated malaria Rashes Meningococcemia, dengue , measles, rickettsial diseases, arboviral diseases Petechiae Dengue, meningococcemia , hemorrhagic fevers Head and scalp Traumatic/ non accidental injury hematomas Dysmorphism, Possibility of seizures neurocutaneusmarkers Abnormal odour DKA, hepatic coma Cyanosis Cyanotic congenital heart disease, Hypoxia Oedema CHF, Renal failure Dehydration Hypovolemic shock, HUS Respiratory Patterns ,, Cheyne-Stokes respiration - Denotes a cyclic pattern of alternating hyperpnea and apnea. - A bilateral hemispheric or diencephalic insult may indicate incipient transtentorial herniation - CHF,COPD,OSA,Uremia. Hyperventilation - Injury in the pontine or midbrain tegmentum; - respiratory failure, hemodynamic shock, fever, sepsis, metabolic disarray, and psychiatric disease. Apneustic breathing - prolonged pause at the end of inspiration - lateral tegmentum of the lower half of the pons. Cluster breathing - Periodic respirations that are irregular in frequency and amplitude with variablepauses between clusters of breaths - lower pontine tegmental lesion Ataxic breathing - Is irregular in both rate and tidal volume - Suggests damage to the medulla.

Neurological Assesment

 Level of consciousness  Pupillary responses  Brainstem function  Motor response  Other neurological findings Herniation syndrome A. Level of conciousness

• The level of conciousness must be recorded in the form of an objective scale. • The Glasgow coma scale is a useful tool for the grading of the degree of altered consciousness and the severity of CNS insult.

• FOUR Scale Glasgow coma scale BEST RESPONSE ACTIVITY Adults/Older Children Infants ( modified GCS ) Score

1. Spontaneous 1. Spontaneous 4 Eye Opening 2. To speech 2. To speech 3 ( E ) 3. To pain 3. To pain 2 4. None 4. None 1

1. Appropriate speech 1. Coos, babbles 5 2. Confused speech 2. Irritable, cries but 4 3. Inappropriate words consolable Verbal 4. Incomprehensible or 3. Cries, inconsolable ( V ) none specific sounds 3 4. Moans to pain 5. None 2

5. None 1

1.Obeys commands 1. Spontaneous 6 movement 2.Localizes pain 2. Withdraws to touch 5 Motor 3.Withdraws to pain 3. Withdraws to pain 4 4.Decorticate to pain 3 ( M ) 4. Decorticate to pain 5.Decerebrate to pain 2 5. Decerebrate to pain 6.None 1 6. None

B. Size and reactivity of pupils

Pupils Lesion/Dysfunction Pinpoint Pons, opiates, cholinergic intoxication Mid position – Midbrain lesion fixed or irregular Unilateral , dilated and fixed Uncal herniation Bilateral , dilated and fixed Diffuse damage, central herniation, global hypoxia ischemia, barbiturates, atropine C. Brainstem function

• Pupillary light reflex - Area tested – CN II ,III, midbrain. - Midposition (4-6mm) or fully dilated pupils, not reactive to light – consistent with brain death.

• Oculocephalic reflex (doll’s eye reflex) Area tested – CN III, VI and VIII, midbrain , pons. -Should not be performed patient with cervical injury. -Intact patient – eyes remain fixed on a distant spot as if maintaining eye contact. -Brain death- eyes move with patient head movement.

• Oculovestibular reflex (caloric reflex) Area tested – CN III, IV, VI and VIII, pons, midbrain. -Brain death – Absent of eye movement.

• Corneal reflex Area tested – CN III,V and VII, pons. -Intact patient – touch result in eyelid closure and eye may rotate upward. -Brain death– no response.

• Gag reflex Area tested – CN IX and X , medulla. -Brain death – absence of both cough and gag reflex. D. Motor response

• Single best indicator of the depth and severity of coma 1. Spontaneous movements. 2. Tone and reflexes 3. Induced movements.

• Decorticate posturing with flexion of the upper extremities and extension of the lower extremities suggests involvement of the cerebral cortex and preservation of brainstem function. • Decerebrate posturing with rigid extension of the arms and legs is indicative of cortical and brainstem damage.

E. Other neurological findings • Fundus examination : Papilloedema, Retinal hemorrhages • Signs of meningeal irritation • Cranial nerve Examination E. Herniation syndromes

• Brain tissue deforms intracranially and moves from higher to low pressure when there is asymmetric, unilateral or generalised increase in intracranial pressure. • Signs of cerebral herniation 1. Glasgow coma score <8 2. Abnormal pupil size and reaction (unilateral or bilateral) 3. Absent doll’s eye movements 4. Abnormal tone (decerebrate/decorticate posturing, flaccidity) 5. Hypertension with bradycardia 6. Respiratory abnormalities (hyperventilation, Cheyne- Stokes breathing, apnea, respiratory arrest) 7. Papilledema

Types Clinical manifestation Central herniation Impaired consciousness, abnormal respiration, small reactive / midposition fixed pupil decorticate evolving to decerebrate posture

Uncal Herniation Impaired consciousness, abnormal respirations,unilateral dilated pupil, ptosis, unilateral hemiparesis

Foramen magnum or Tonsillar Impaired consciousness, neck rigidity, opisthotonus, decerebrate herniation rigidity, vomiting, irregular respirations, apnea, bradycardia Investigations

Neuroimaging: • CT scan: • Magnetic Resonance Imaging (MRI)

Biochemical investigations EEG findings in coma • High voltage slow waves – Underlying supratentorial • Triphasic waves- Hepatic coma lesion

• PLEDS Periodic Lateralized Epileptiform • Slowing of background activity – Metabolic coma Discharges – Herpes Encephalitis

Prognosis

• The prognosis for recovery from coma depends primarily on the cause, rather than on the depth of coma. • Coma from drug intoxication and metabolic causes carry the best prognosis.

• Prolonged coma after a global hypoxic ischemic insult carries a poor prognosis.

• Infectious encephalopathies have a good outcome with mild or moderate difficulties only. References

 Plum and Posner’s diagnosis of stupor and coma- 4th edition  Practice guidelines update – AAN  Neurocritical care, Michel T.Torbey  Zakaria Z, Abdullah MM, Halim SA, Ghani ARI, Idris Z, Abdullah JM. The Neurological Exam of a Comatose Patient: An Essential Practical Guide. Malays J Med Sci. 2020 Oct;27(5):108-123. doi: 10.21315/mjms2020.27.5.11. Epub 2020 Oct 27. PMID: 33154707; PMCID: PMC7605838.  Eapen BC, Georgekutty J, Subbarao B, Bavishi S, Cifu DX. Disorders of Consciousness. Phys Med Rehabil Clin N Am. 2017 May;28(2):245-258. doi: 10.1016/j.pmr.2016.12.003. Epub 2017 Mar 1. PMID: 28390511.