Encephalopathy and Coma

Post a comment   Post Comment on Twitter
 


Comments

    Notes
    Hide
     1  Encephalopathy and Coma Neurologic Emergencies July 17, 2007
     2  Case Presentation 35 year-old man who, after 2 months of increasingly severe left-sided headaches, became rapidly lethargic and then stuporous.
     3  Unconsciousness vs. unresponsiveness
     4  Unconsciousness Loss of consciousness requires: Disruption of ascending reticular activating system OR Bihemispheric cerebral dysfunction
     5  Unconsciousness Loss of consciousness requires: Disruption of ascending reticular activating system OR Bihemispheric cerebral dysfunction Often transient
     6  Unconsciousness Loss of consciousness requires: Disruption of ascending reticular activating system OR Bihemispheric cerebral dysfunction Often transient OR Dominant hemisphere lesions
     7  Unresponsiveness Ability to respond requires: Consciousness Language Subcortical and cortical motor system integrity Descending pyramidal tracts Etc..
     8  Coma A state of “unarousable unresponsiveness”
     9  Approach to unresponsive patient This is an emergency! Immediate evaluation should include: Airway Breathing Circulation Glucose Electrolytes, ABG, liver and thyroid function tests, CBC, toxicology screen, ECG
     10  Approach to unresponsive patient Empiric treatments when indicated Supplemental oxygen Intubation if needed Intravenous fluids Thiamine 100mg IV If there is a malnourished appearance or if there is a known history of alcoholism Before glucose!! Glucose
     11  Approach to unresponsive patient Empiric treatments when indicated Lower the intracranial pressure Mannitol 0.25 to 2.0 grams/kg IV (15-25% solution) over 60 minutes Hyperventilation (target pCO2 25-30 mmHg) Remember concept of rebound Naloxone/flumazenil Treat seizures Empiric treatment for acute CNS infection
     12  Examining the unresponsive patient Outline of examination Observation Respiratory pattern Verbal responses Eye opening Pupillary reactions Spontaneous eye movements Oculocephalic responses = Oculovestibular responses Corneal responses Motor responses Tendon reflexes Muscle tone Elicit meningismus
     13  Examining the unresponsive patient Reproducibility is key Observation before stimuli Stepwise approach to stimuli Verbal stimulation – call pt’s name loudly Gentle tactile stimulation – shake/hold pt’s hand Noxious tactile stimulation – shoulder pinch Noxious stimuli on each limb – nailbed pressure Important part of motor and sensory exam Record each behavior (or lack thereof) sequentially
     14  Examining the unresponsive patient Reproducibility is key Give simple verbal instructions Ask for a motor response from each limb Eye and eyelid movements Record each behavior (or lack thereof) sequentially
     15  Example “The patient lay motionless in bed unless called loudly by name, when he opened his eyes only briefly and looked only to the left. He failed to respond verbally to questions. He did not follow any instructions. He withdrew from nailbed pressure with his left arm and leg vigorously, but not with his right arm/leg.”
     16  Examining the unresponsive patient Always assume the patient can hear you. Introduce yourself and explain your exam. Do not forget to look for vertical eye and eyelid movements. Develop a routine for examining and recording.
     17  Case Presentation Examination also shows: The left pupil is dilated and unreactive. The left eye fails to adduct during oculovestibular testing. There is left-sided hemiplegia.
     18  Your diagnosis?
     19  Your diagnosis? Empiric treatment?
     20  
     21  Approach to an unresponsive patient Identification of syndrome Localization Differential diagnosis Evaluation Treatment Prognosis
     22  Findings with Localizing Value The pupils Respiratory patterns Eye movements Motor activity of body and limbs
     23  
     24  Pupillary responses Pupillary pathways are most resistent to metabolic insults Excellent localizing value Helpful differentiating metabolic from structural causes of coma The unilateral dilated and unreactive pupil Oculomotor nerve compression Posterior communicating artery aneurysm Uncal herniation
     25  
     26  Pupillary responses REMEMBER: 8 – 18% of population has a physiologic anisocoria of at least 0.5mm Probably should assume that this represents pathology in an emergency situation
     27  Pupillary responses Ciliospinal reflex Pinch skin of face or neck and watch for bilateral pupil dilation (1-2mm) Tests integrity of: Trigeminal nerve/spinal dorsal horn Brainstem autonomic centers C8-T2 levels (ciliospinal center of Budge) Ascending autonomic fibers
     28  Cheyne-Stokes respirations Forebrain/diencephalic lesions Central neurogenic hyperventilation Mibrain/pons lesions Apneustic breathing Bilateral pontine tegmentum lesions Cluster breathing Lesions near pontomedullary junction Apnea Bilateral ventrolateral medullary lesions
     29  
     30  Decerebrate rigidity/posture The arms are held in adduction and extension with the wrists fully pronated. Extension, internal rotation, and plantar flexion in the lower extremities.
     31  Decerebrate rigidity/posture Experimentally produced by transection at the collicular level between the red nuclei and vestibular nuclei In theory: disinhibited vestibular tone increases extensor tone in limbs Think: Metabolic disorders (anoxia, others) Midbrain/upper pons lesions (infarcts) Downward transtentorial herniation Space-occupying lesions in posterior fossa
     32  Decerebrate rigidity/posture Sometimes accompanied by opisthotonus, an arching of the trunk usually with clenched teeth and tonic neck and arm posturing.
     33  Decorticate rigidity/posture Flexion of the arms, wrists, and fingers. Adduction of upper extremities. Extension, internal rotation, and plantar flexion in the lower extremities.
     34  Decorticate rigidity/posture Experimentally produced by bilateral lesions from forebrain down to the level of the rostral midbrain. If unilateral, the rigidity will be contralateral to the involved cerebral hemisphere. Less specific in terms of localization and etiology.
     35  
     36  Syndromes of Unresponsiveness Encephalopathy and coma Acute confusional state/delirium Locked-in syndrome Akinetic mutism Catatonia Psychogenic unresponsiveness Persistent vegetative state
     37  Akinetic mutism The patient is seemingly awake but remains silent and motionless. Failure to gain patient’s attention and interest. Eyes often fix on examiner and will follow moving objects. They may also follow auditory stimuli. May have frontal release signs or signs of corticospinal tract involvement. May also exhibit stereotyped limb movements.
     38  Akinetic mutism Some may try to speak spontaneously Can be difficult to distinguish from psychogenic and/or catatonic unresponsiveness. EEG will show generalized slowing.
     39  Akinetic mutism This syndrome does have localizing value Causative lesions can be: Bilateral frontal regions, especially the anterior cingulate gyri The diencephalo-mesencephalic reticular formation The globus pallidus The hypothalamus NOTE: this is NOT a psychiatric diagnosis
     40  Akinetic mutism More common causative conditions: Anoxia Head trauma Cerebral infarction Severe acute hydrocephalus Compression by tumor
     41  Locked-In Syndrome Unresponsiveness except for vertical eye and eyelid movements. These patients are often awake, alert, and completely conscious. Lesion of ventral pons (basis pontis) Causes: Basilar artery thrombosis Pontine hemorrhage/tumor Central pontine myelinolysis
     42  Delirium Or “acute confusional state” Acute cognitive impairment Disorientation Attentional abnormalities Increased or decreased psychomotor activity (“agitated” or “quiet” delirium) Disorder of the sleep/wake cycle
     43  Delirium Testing attention: Counting, serial 7s, spelling “world” backwards
     44  Delirium Common! 10-15% of medical/surgical ward pts Even higher prevalence in elderly 32% prevalence in pts after cardiac surgery 45-55% prevalence in pts after hip fracture surgery 70% prevalence in pts with bacteremia
     45  Case 2 65 year-old man suddenly collapsed. EMS intubated him. On exam the patient is comatose. He has pinpoint pupils and ocular bobbing. There is spontaneous decerebrate posturing. He has bilateral extensor toe signs.
     46  
     47  Case 2 Hyperdense basilar artery sign Presumed basilar artery thrombosis/embolism Treatment?
     48  Case 2 Hyperdense basilar artery sign Presumed basilar artery thrombosis/embolism Treatment? Intra-arterial tPA MERCI retrieval/thrombectomy