Approach to the Comatose patient
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Coma is defined and the anatomy of consciousness explained. The various levels of arousal, AVPU scale and Glasgow Coma Scale described. The differential diagnosis of coma discussed are coma with & without focal deficits and the meningitis syndrome. The various aspects of history discussed in details. The examination part includes the general examination, Brainstem reflexes, motor functions with the signs of lateralisation and meningeal irritation signs. The basic lab investigations, Imaging and special investigations like CSF examination, EEG discussed. Elevated intracranial pressure and its management explained.
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Approach to the Comatose patient
- 1. APPROACH TO COMA Dr Abdullah Ansari
- 2. Definition of Coma Coma is a state of complete behavioral unresponsiveness to external stimulation
- 3. Anatomy of consciousness ī¨ Ascending reticular activating system (ARAS) ī¤ Activating systems of upper brainstem, hypothalamus, thalamus ī¤ Determines the level of arousal ī¨ Cerebral hemispheres and interaction between functional areas in cerebral hemispheres ī¤ Determines the intellectual and emotional functioning ī¨ Interaction between cerebral hemispheres and activating systems
- 4. Ascending RAS ī¨ The ascending RAS, from the lower border of the pons to the ventromedial thalamus ī¨ The cells of origin of this system occupy a paramedian area in the brainstem
- 5. Levels of arousal (consciousness) ī¨ Conscious: alert, attentive and cooperative, awareness of self and environment ī¨ Confused: conscious but talks irrelevantly ī¨ Drowsy: sleepy but can be aroused easily by external stimulus ī¨ Stupor: Deep sleep, can only be aroused by painful stimulus ī¨ Coma: unconsious, no response to external stimuli
- 6. AVPU scale ī¨ Alert: The patient is awake ī¨ Verbal: The patient responds to verbal stimulation ī¨ Pain: The patient responds to painful stimulation ī¨ Unresponsive: The patient is completely unresponsive EMS crews may begin with AVPU assesment, to be followed by GCS if the score is below "A."
- 7. Glasgow Coma Scale (GCS) Best eye response (E) Best verbal response (V) Best motor response (M) 4 Eyes opening spontaneously 5 Oriented 6 Obeys commands 3 Eye opening to speech 4 Confused 5 Localizes to pain 2 Eye opening in response to pain 3 Inappropriate words 4 Withdraws from pain 1 No eye opening 2 Incomprehensible sounds 3 Flexion in response to pain 1 None 2 Extension to pain 1 No motor response
- 8. Glasgow coma scale ī¨ Individual elements as well as the sum of the score are important. ī¨ Hence, the score is expressed in the form "GCS 9 = E2 V4 M3 ī¨ Generally, comas are classified as: ī¤ Severe, with GCS ⤠8 ī¤ Moderate, GCS 9 - 12 ī¤ Minor, GCS âĨ 13.
- 9. Differential Diagnosis of Coma
- 10. Differential Diagnosis of Coma 1. No focal neurologic signs, CT scan and cellular content of the CSF are normal 2. Focal neurological signs, with or without changes in the CSF; CT and MRI are abnormal 3. Meningitis syndromes, with an excess of WBCs in the CSF, usually without focal signs; CT or MRI shows no mass lesion
- 11. Diseases without focal neurological signs Diseases that cause no focal or lateralizing neurologic signs, usually with normal brainstem functions; CT scan and cellular content of the CSF are normal a. Intoxications: alcohol, sedative drugs, opiates, etc. b. Metabolic disturbances: anoxia, hyponatremia, hypernatremia, hypercalcemia, diabetic ketoacidosis, hypoglycemia, uremia, hepatic coma, hypercarbia, Addisonian crisis c. Severe systemic infections: septicemia, typhoid fever, malaria d. Shock from any cause e. Postseizure states, status epilepticus, nonconvulsive status epilepticus f. Hypertensive encephalopathy, eclampsia g. Severe hyperthermia, hypothermia
- 12. Diseases with focal neurological signs Diseases that cause focal brainstem or lateralizing cerebral signs, with or without changes in the CSF; CT and MRI are abnormal a. CNS hemorrhage or infarction b. Brain abscess, subdural empyema c. Brain tumor with surrounding edema d. Brain trauma: Epidural and subdural hemorrhage, brain contusion e. Metabolic coma (see above) with preexisting focal damage f. Miscellaneous: Cortical vein thrombosis, herpes simplex encephalitis, septic emboli due to bacterial endocarditis, acute disseminated encephalomyelitis, thrombotic thrombocytopenic purpura, cerebral vasculitis
- 13. Meningitis syndromes Diseases that cause meningeal irritation with or without fever, and with an excess of WBCs or RBCs in the CSF, usually without focal or lateralizing cerebral or brainstem signs; CT or MRI shows no mass lesion a. Subarachnoid hemorrhage from ruptured aneurysm, arteriovenous malformation, trauma b. Acute bacterial meningitis c. Viral encephalitis d. Miscellaneous: fat embolism, cholesterol embolism, carcinomatous and lymphomatous meningitis
- 14. Approach to Coma
- 15. Approach to Coma ī¨ General examination: On arrival to ER immediate attention to: ī¤ Airway ī¤ Breathing ī¤ Circulation ī¤ establishing IV access ī¤ Blood should be withdrawn: estimation of glucose # other biochemical parameters # drug screening
- 16. ApproachâĻ ī¨ Attention is then directed towards: ī¤ Assessment of the patient ī¤ Severity of the coma ī¤ Diagnostic evaluation ī¨ All possible information from: ī¤ Relatives ī¤ Paramedics ī¤ Ambulance personnel ī¤ Bystanders particularly about the mode of onset
- 17. History 1. The circumstances and rapidity with which neurologic symptoms developed 2. The antecedent symptoms (confusion, weakness, headache, fever, seizures, dizziness, double vision, or vomiting) 3. The use of medications, drugs, or alcohol 4. Chronic liver, kidney, lung, heart, or other medical disease
- 18. ApproachâĻ ī¨ Clues obtained from the patient's īŽ Clothing or īŽ Handbag ī¨ Careful examination for īŽ Trauma requires complete exposure and âlog rollâ to examine the back īŽ Needle marks
- 19. ApproachâĻ ī¨ If head trauma is suspected, the examination must await adequate stabilization of the neck. ī¨ Glasgow Coma Scale: the severity of coma is essential for subsequent management. ī¨ Following this, particular attention should be paid to brainstem and motor function.
- 21. General examâĻ Pulse ī¨ Bradycardia: brain tumors, opiates, ICT, myxedema ī¨ Tachycardia: sepsis, hyperthyroidism, uremia Blood Pressure ī¨ High: hypertensive encephalopathy ī¨ Low: Addisonian crisis, alcohol, barbiturate, MI, sepsis
- 22. General examâĻ Temperature ī¨ Fever in sepsis, meningitis, encephalitis, heat stroke, anticholinergic drug intoxication ī¨ Hypothermia in alcohol, barbiturate, sedative intoxication; hypoglycemia, peripheral circulatory failure Respiratory rate ī¨ Tachypnea in acidosis or pneumonia ī¨ Aberrant respiratory patterns in brainstem disorders
- 23. General examâĻ Skin ī¨ Injuries, Bruises: traumatic causes ī¨ Dry Skin: DKA, Atropine ī¨ Moist skin: Hypoglycemic coma ī¨ Cherry-red: CO poisoning ī¨ Needle marks: drug addiction ī¨ Rashes: meningitis, endocarditis
- 24. General examâĻ Odour of breath ī¨ Acetone: DKA ī¨ Fetor Hepaticus: in hepatic coma ī¨ Urineferous odour: in uremic coma ī¨ Alcohol odour: in alcohol intoxication
- 25. Level of Arousal ī¨ Tickling the nostrils with a cotton wisp is a moderate stimulus to arousal ī¨ Pressure on the knuckles or bony prominences and pinprick stimulation are humane forms of noxious stimuli ī¨ Pinching skin causes unsightly ecchymoses and is generally not necessary but may be useful in eliciting abduction withdrawal movements of the limbs
- 26. Posturing Decorticate rigidity ī¨ Flexion of the elbows and wrists and supination of the arm ī¨ Bilateral damage rostral to midbrain Decerebrate rigidity ī¨ Extension of the elbows and wrists with pronation ī¨ Damage to motor tracts in the midbrain or caudal diencephalon
- 27. Posturing
- 28. Brainstem Reflexes The brainstem reflexes that are examined are 1. Pupillary reflex 2. Ocular movements 3. Corneal reflex 4. Respiratory pattern ī¨ As a rule, coma due to bilateral hemispheral disease preserves these brainstem activities
- 29. Pupils Pupils ī¨ Size, inequality, reaction to a bright light. ī¨ An important general rule: most metabolic encephalopathies give small pupils with preserved light reflex. ī¨ Atropine, and cerebral anoxia tend to dilate the pupils, and opiates will constrict them.
- 30. Pupils Reactive and round pupils of midsize (2.5â5 mm) essentially exclude midbrain damage
- 31. Pupils Structural lesions are more commonly associated with pupillary asymmetry and with loss of light reflex. ī¨ Midbrain lesions : round, regular, medium-sized pupils, do not react to light ī¨ Cranial nerve III distal to the nucleus: Ipsilateral fixed, dilated pupil ī¨ Pontine lesions: bilaterally small pupils, {in pontine hge, may be pinpoint, although reactive}
- 32. Pupils ī¨ Lateral medullary lesion: ipsilateral Horner's syndrome. ī¨ Occluded carotid artery causing cerebral infarction: Pupil on that side is often small
- 33. Small, reactive Diencephalons Dilated, Fixed small, pinpoint In hge reactive Pons Midbrain Ipsilateral dilated, Fixed Medium-sized, fixed .
- 34. Ocular movements ī¨ The position of the eyes at rest ī¨ Presence of spontaneous eye movement ī¨ The reflex responses to oculocephalic and oculovestibular maneuvers ī¨ The eyes look toward a hemispheral lesion and away from a brainstem lesion.
- 35. The oculocephalic reflex ī¨ The oculocephalic reflexes, elicited by moving the head from side to side or vertically and observing eye movements in the direction opposite to the head movement ī¨ If the eyes move conjugately in the opposite direction to that of head movement, the response is positive and indicates an intact pons mediating a normal vestibulo-ocular reflex ī¨ The âdollâs eyesâ refers to the reflex elevation of the eyelids with flexion of the neck ī¨ These reflexes are normally suppressed in the awake patient
- 37. The oculovestibular reflex ī¨ These are tested by the installation of ice-cold water into the external auditory meatus, having confirmed that there is no tympanic rupture. ī¨ A normal response in a conscious patient is the development of nystagmus with the quick phase away from the stimulated side This requires intact cerebropontine connections
- 39. Respiration ī¨ CheyneâStokes respiration: (hyperpnoea alternates with apneas) is commonly found in comatose patients, often with cerebral disease, but is relatively non-specific. ī¨ Rapid, regular respiration is also common in comatose patients and is often found with pneumonia or acidosis.
- 40. Respiration ī¨ Central neurogenic hyperventilation ī¨ Brainstem tegmentum (mostly tumors): ī¤ â PO2, â PCO2, and ī¤ Respiratory alkalosis in the absence of any evidence of pulmonary disease ī¨ Sometimes complicates hepatic encephalopathy
- 41. Respiration ī¨ Apneustic breathing ī¤ Brainstem lesions Pons may also give with a pause at full inspiration ī¨ Ataxic: ī¤ Medullary lesions: irregular respiration with random deep and shallow breaths
- 43. Abnormal breathing patterns in coma Midbrain Pons Medulla ARAS Cheynes - Stokes Ataxic Apneustic Central Neurogenic
- 44. Motor function ī¨ Particular attention should be directed towards asymmetry of tone or movement. ī¨ The plantar responses are usually extensor, but asymmetry is again important. ī¨ The tendon reflexes are less useful. ī¨ The motor response to painful stimuli should be assessed carefully (part of GCS)
- 45. Motor function ī¨ Painful stimuli: supraorbital nerve pressure and nail-bed pressure. Rubbing of the sternum should be avoided (bruising and distress to the relatives) ī¨ Patients may localize or exhibit a variety of responses, asymmetry is important
- 46. Motor function ī¨ Flexion of the upper limb with extension of the lower limb (decorticate response) and extension of the upper and lower limb (decerebrate response) indicate a more severe disturbance and prognosis.
- 47. Signs of lateralization ī¨ Unequal pupils ī¨ Deviation of the eyes to one side ī¨ Facial asymmetry ī¨ Turning of the head to one side ī¨ Unilateral hypo-hypertonia ī¨ Asymmetric deep reflexes ī¨ Unilateral extensor plantar response (Babinski) ī¨ Unilateral focal or Jacksonian fits
- 48. Meningeal irritation signs 1. Neck rigidity 2. Kernigâs sign 3. Brudzinskiâs sign
- 50. Head and Neck Head and neck ī¨ The head ī¤ Evidence of injury ī¤ Skull should be palpated for depressed fractures. ī¨ The ears and nose: haemorrhage and leakage of CSF ī¨ The fundi: papilloedema or subhyaloid or retinal haemorrhages
- 52. Laboratories ī¨ Obtain ABG, serum electrolytes, glucose, creatinine, complete blood count, liver functions and urinalysis ī¨ Drug levels ordered if appropriate ī¨ Toxicology screen of blood and urine if suspected
- 53. Imaging ī¨ A head CT should be obtained to evaluate for structural abnormalities ī¨ Brain MRI can be useful if head CT is nondiagnostic and there is suspicion for an ischemic or parenchymal lesion (especially of the posterior fossa)
- 55. Cerebrospinal fluid (CSF) examination ī¨ Lumbar puncture (LP) considered in patients with fever and/or new headache ī¨ A fundus examination and/or head imaging prior to LP to assess risk of herniation ī¨ Basic cerebrospinal fluid (CSF) studies (e.g. protein, glucose, cell count, Gram stain, and aerobic culture) obtained with additional studies depending on the possible etiology
- 56. Electroencephalography (EEG) ī¨ Electroencephalography (EEG) to rule out seizures ī¨ Nonconvulsive status epilepticus is a common cause of unexplained encephalopathy in the critically ills
- 59. Treatment of Elevated ICP ī¨ Insert ICP monitorâventriculostomy versus parenchymal device ī¨ General goals: maintain ICP <20 mmHg and CPP âĨ60 mmHg
- 60. Treatment of Elevated ICP 1. Elevate head of the bed; midline head position 2. Drain CSF via ventriculostomy (if in place) 3. Osmotherapyâmannitol or hypertonic saline 4. Glucocorticoidsâfor vasogenic edema from tumor, abscess 5. Hyperventilationâto PaCO2 30â35 mmHg 6. Pressor therapyâ dopamine or norepinephrine to maintain adequate MAP to ensure CPP âĨ60 mmHg 7. Second-tier therapies for refractory elevated ICP a. Decompressive craniectomy b. High-dose barbiturate therapy (âpentobarb comaâ) c. Hypothermia to 33°C
- 61. Prognosis
- 62. Prognosis in coma ī¨ In general, coma carries a serious prognosis ī¨ This is dependent to a large extent on the underlying cause ī¨ Coma due to depressant drugs carries an excellent prognosis provided that resuscitative and supportive measures are available and no anoxia has been sustained ī¨ Metabolic causes, apart from anoxia, carry a better prognosis than structural lesions and head injury
- 63. Prognosis in coma ī¨ Length of coma and increasing age are of poor prognostic significance. ī¨ Brainstem reflexes early in the coma are an important predictor of outcome