Neurological Assessment of the Comatose Patient

1. Neurological Assessment of the Comatose Patient Galen V. Henderson, MD Brigham and Women’s Hospital Director, Neuroscience ICU Harvard Medical School

3. Neuro exam Remains a critical in the clinical decision-making process. • Does the patient who just collapsed on the street have cardiac disease/cardiac arrest or an cerebral hemorrhage? • Does the patient with nausea and vomiting need a gastroenterology consult or a head CT to evaluate for a brain tumor and increased ICP?

4. Outline Review Consciousness and Coma Pathophysiology Discuss major syndromes of impaired states of consciousness Review how to examine the sedated and comatose patient Discuss the complete comatose examination – and Dx of death by neurological criteria

5. Case • 56-year-old female underwent left hip arthroplasty • In the PACU 7:15PM, she complained of pain and received 100 mcg of fentanyl. • 9:30PM ~oriented to person/place/time, with a reported "intact" neurological exam and moving all extremities. • She received some Toradol and fell asleep.

6. Case • Nurses noted she was becoming increasingly somnolent. • Around 1:00AM, She required face mask oxygen and she became poorly responsive (even to sternal rub). • She then received Narcan and Flumazenil but did not respond. • Per the PACU nurses, the patient had been on telemetry and continuous oxygen monitoring (with no alarms). An electrocardiogram showed sinus rhythm

7. Consciousness • Consciousnessis multifaceted • Essential components are alertness and awareness of self and the environment • Alertness (arousability) as a prerequisite for other aspects of consciousness. • Full awareness an appropriate behavioral responses involve: • Sensation • Perception • Memory function • Attention (with links to motivation) • Cognition

8. LEVELS OF CONSCIOUSNESS Alert  normal awake and responsive state Lethargic  easily aroused with mild stim.  Can maintain arousal. Somnolent  easily aroused by voice or touch; awakens and follows commands; required stimulation to maintain arousal  Obtunded/Stuporous: arousable only with repeated and painful stimulation; verbal output is unintelligible or nil; some purposeful movement to noxious stimulation Comatose  no arousal despite vigorous stim, no purposeful movement- only posturing, brainstem reflexes often absent/present, respirations may be varying

9. Characteristics of major clinical syndromes

10. PATHOPHYSIOLOGY OF COMA Bilateral diffuse hemisphere disease Brainstem reticular formation disease

11. The Examination Level of consciousness is then noted by the patients reaction to: Calling of his/her name Simple commands Noxious stimuli such as tickling the nares, supraorbital or sternal pressure, pinching the side of the neck or inner parts of the arms or thighs, or applying pressure to the knuckles

12. NEUROLOGICAL EXAM OBSERVATION Respiratory pattern 1. Normal 2. Periodic (Cheyne-Stroke or other) 3. Hyperventilation (compensatory vs. primary) 4. Apneustic (pontine) 5. Ataxic (medullary) 6. Apnea Automatisms 1. Good - yawn; sneeze 2. Bad - cough; swallow; hiccups

13. Mental Status Examination • Taking the history is 80% of the localization • ESSENTIALS OF HISTORY • Pace (i.e. rate of onset) • Toxins and drugs (alcohol, meds, CO) • Trauma • Fever • Headache • Similar episodes in the past

14. Mental Status Examination Level of consciousness Normal, depressed Orientation Person, place and time Attention Calculations, digit span, spelling “world” backwards Memory

15. NERUOLOGICAL EXAM CRANIAL NERVES I- not testable; smelling salts tests pain (V) II - visual threat for fields & fundi III, IV, VI, VIII 1. Pupils - size; reaction (No PERRLA) 2. Eye movements - no head turning allowed A. spontaneous B. ice water calorics V, VII - corneal reflex IX, X - gag reflex and swallowing XI, XII - not tested acutely

16. Eyes are of great importance Normal pupillary size, shape and light reflexes indicate integrity of the midbrain structures Loss of light reaction usually precedes enlargement of the pupil The pupil may become oval or pear-shaped appear to be off center (corectopia) because of a differential loss of innervation of a portion of the pupillary sphincter As midbrain displacement continues, both pupils dilate and become unreactive to light as a result of the compression of the oculomotor nuclei in the rostral midbrain In the last step in the evolution of brainstem compression, there tends to be a slight reduction in pupillary size on both sides to 5mm or smaller

17. PUPILS: • CN II afferent, CN III efferent.  Tests level of the midbrain as well as autonomic integrity.  • Some patterns: •  Hypothalamus: Horner’s (miosis, ptosis, and anhydrosis) • Midbrain: midposition, fixed • Peripheral III: usually unilateral, more dilated, fixed • Pons: pin point pupils • Medulla (lat): Horner’s- preserved response to light • Metabolic: in general metabolic derangements do not affect pupils.  (Roving) • The major exceptions are sympathomimetics and anti-cholinergics which dilate, and opiates which cause pin point pupils

18. Cranial Nerves 2 • Visual Acuity • Visual Fields • Confrontation • Threat testing • Fundoscopic examination

19. CN 2 Left Right

21. Vertical Eye Movements

22. EXAM OF CRANIAL NERVES I- not testable; smelling salts tests pain (V) II - visual threat for fields & acuity; fundi III, IV, VI, VIII 1. Pupils - size; reaction (No PERRLA) 2. Eye movements - no head turning allowed A. spontaneous B. ice water calorics V, VII - corneal reflex IX, X - gag reflex and swallowing XI, XII - not tested acutely

23. Eye Movements-CN 3, 4, 6 • Describe the size and shape of pupils to light. • Check for lid droop, lag, or retraction. • Ask the patient to follow a small object at a distance of 2 ft • Move the target slowly in both horizontal and vertical planes; observe any weakness, nystagmus • Doll’s eyes/cold calorics reflex

24. Cranial Nerve 3,4 and 6 • CN 3 • Pupilary constriction to direct/consensual light • Argyll-Robertson pupil • Reacts to near vision but not to light • Marcus-Gunn pupil • Impaired constriction to direct light and normal consensual response • Constriction to near vision (not accommadation) • Swinging flashlight test

25. Eye Movements • Movements are checked in all 6 directions of gaze • Ask about diplopia • Conjugate gaze • Nystagmus • Primary gaze • Volitional eye movements

26. CN 5 • V1, V2, and V3 • Corneal Reflex • Blink occurs if V and VII are intact • Compare the sides for symmetry

27. CN 7 • Facial symmetry • Look in particular for differences in strength of the lower versus upper facial muscles.

28. Types of Facial Weakness

29. CN 9, 10, 11 and 12 • Palatal elevation • Ahh • Pharyngeal ('gag') reflex • Gag • Swallowing/voice quality • Trapezius • Tongue protrusion

30. Palate and Tongue

31. EXAM OF THE MOTOR SYSTEM Spontaneous movement - compare sides Induced movement (noxious stimuli) Paralysis - does not localize Purposeful/Nonpurposeful Antigravity postures (Posturing) Decorticate:  extension LE, flexion at elbows/wrists Better prognosis than decerebrate Often without concomitant loss neuro-optho reflexes  Usually lesion is above the midbrain Decerebrate:  extension LE, extension/pronation/adduction UE Often with neuro-ophtho changes Most commonly lesion at level of midbrain or diencephalon

32. Motor • Strength0 = no movement 1 = flicker or trace of contraction but no associated movement at a joint2 = movement with gravity eliminated3 = movement against gravity but not against resistance 4 = movement against moderate resistance 5 = full power

33. EXAM OF THE SENSORY SYSTEM Hemisensory deficit Level on the trunk - myelopathy

34. NEUROLOGICAL EXAM REFLEXES Proprioceptive (tendon jerks) Nocioceptive (plantar; corneal) Antigravity (decerebration; decortication)

35. Reflexes • Commonly tested are: • Biceps (C5, C6) • Brachioradialis (C5, C6) • Triceps (C7, C8) • Patellar (L3, L4) • Achilles (S1, S2) • Reflexes are graded according to the following scale: 0 = absent 1 = present but diminished 2 = normoactive 3 = exaggerated 4 = clonus

36. Extensor Planters

37. N Engl J Med 344:1215, April 19, 2001

38. Death Cardiac death (the heart stops) Absence of radial, carotid or femoral pulses Absence of heart tones at apex of heart by auscultation Absence of breath sounds by auscultation Pupils nonreactive Ascertain that the patient does not rouse to verbal or tactile stimuli Brain death (the brain stops) irreversible loss of function of the brain, including the brainstem Exam is much more complicated

39. Evolution of Brain Death Concept • Uniform Determination of Death Act (1981) • Death can be diagnosed by neurologic criteria • Does not define any of the specifics of the clinical diagnosis • There is a clear difference between severe brain damage and brain death • 1995: AAN Guidelines in Neurology (1995 45:1012.) • “…irreversible loss of function of the brain, including the brainstem” • Specifically addressed • clinical examination • validity of confirmatory tests • provided a practical description of apnea testing

40. Clinical Evaluation of Brain Death: No Cerebral Response to Painful Stimulus Spinal Reflexes Permitted but no posturing allowed Absence of Brainstem Function Tested by Cranial Nerve Examination Interval Between Exams Arbitrary, Often 6 Hours Adequate Vital Signs Required SpO2 over 90% SBP over 90 mmHg Apnea Examination (Clinical examinations performed twice and apnea testing occurs once)

41. The Core of the Examination Part I: Coma Part II: Absence of brainstem reflexes Pupillary Response to Light Corneal Reflex Gag Reflex Cough Reflex Occulocephalic Reflex (Dolls Eyes)/ Occulovestibular Reflex (Cold Calorics) Part III: Apnea (inferior brainstem)

42. Apnea Testing Prerequisites Core temp > 36.5 C or 97 F Systolic blood pressure > 90 mm Hg Euvolemia or positive fluid balance in the previous 6 hours Normal pCO2 or arterial PCO2 > 40 mm Hg Normal PO2 or preoxygenation to obtain arterial PO2 > 200 Hg

43. Apnea Testing Connect pulse oximeter and disconnect ventilator Deliver 100% O2, 6L/min into trachea Look closely for any movements Measure PO2 and PCO2 and pH after 8-10 min and reconnect ventilator

44. Prerequisites to rule out Severe electrolyte imbalance Acid-base or endocrine disturbance Hypothermia ( < 32 oC or lower) Hypotension Absence of evidence drug intoxication, poisoning, or neuromuscular blocking agents Locked-in-syndrome

45. N Engl J Med 344:1215, April 19, 2001

46. Ancillary laboratory tests Brain death is a clinical diagnosis Repeat clinical examination in 6 hours later is recommended but this interval is arbitrary Ancillary tests are not mandatory but desirable in patients in whom specific testing cannot be reliably performed or evaluated

47. Ancillary Tests --Vascular Conventional Cerebral Angiography Absence of Filling Beyond the Circle Of Willis Pro: Considered “Gold Standard” in Diagnosis of Brain Death1 Con: Requires Extensive, Specific Manpower, Transport out of ICU Cerebral Blood Flow Scan Technetium-99 Radioisotope Study Pro: Can be Done Bedside Con: Requires Specific Manpower, Poor Sensitivity on Posterior Circulation Transcranial Doppler Ultrasonography Absence of Diastolic Flow, Reverberating Flow Indicate High ICP Con: Many Patients Lack Adequate Insonation Windows 1.Morenski JD, et al. J Int Care Med 2003;18(4):211-221

48. Ancillary Tests -- Functional Electroencephalography (EEG) Absence of Electrical Activity for 30 Minutes Specific Criteria For Sensitivity of Recording Pro: Noninvasive, Readily Available Con: Significant Interference from ICU Devices Somatosensory Evoked Potentials Absence of N20-P22 Response from Median Nerve Stimulation Commonly Used Pro: Relatively Widely Available Con: Confounded by Nerve Injury, Tests Limited Regions of Brain