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Clerkship

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Neurology Student Education Director
Maike Blaya, M.D.
131 S. Robertson St.
Suite 1340, Room 1369
Office: 504-988-3888
Fax: 504-988-9197
Email: mblaya1@tulane.edu

Program Coordinator
Zenobia Colón
131 S. Robertson St.
Suite 1340, Room 1345
Office: 504-988-3888
Fax: 504-988-9197
Email: zcolon@tulane.edu

 

Neurology Clerkship
Neurology > Programs > Neurology Clerkship > Coma

Coma

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OBJECTIVES:

  1. Understand the definition of coma, and the terms used to describe the continuum of level of consciousness.

  2. Understand the pathophysiological mechanisms underlying coma, including general principles and specific etiologies.

  3. Be able to generate an appropriate GCS for a coma patient.

  4. Be able to utilize localization principles regarding breathing, brainstem reflexes, motor exam and posturing, and  DTRs.

  5. Understand work-up and management of the comatose patient.

DEFINITIONS:

Coma-  a state of unresponsiveness or unconsciousness characterized by a lack of self- and environmental awareness.


PHYSICAL EXAM OF THE COMATOSE PATIENT:

The physical exam of the comatose patient can be challenging because the patient cannot follow commands.  However, it is actually quite easy to do a methodical and thorough general exam and tailored neuro exam on these patients.  A general exam should always be performed, as it may provide insight into pathophysiology.  In addition to Gen, Heent, Lungs, CV, Abd, and Ext- always include a thorough skin examination for signs of trauma, track marks, or rashes.  Breathing patterns also can facilitate localization, and should be observed and noted.

Just as with a cooperative patient, the comatose patient should be evaluated systematically, including eval of mental status (level of consciousness), CN- esp pupils, Motor, and DTRs.  Evaluation of Coordination is not possible.

BREATHING PATTERNS AND LOCALIZATION:

coma-sm_1

NEUROLOGIC EXAMINATION:


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; req stim to maintain arousal
  • Obtunded/Stuporous  arousable only with repeated and painful stim; verbal output is unintelligible or nil; some purposeful movement to noxious stim
  • Comatose  no arousal despite vigorous stim, no purposeful movement- only posturing, brainstem reflexes often absent       

CRANIAL NERVES AND BRAINSTEM REFLEXES:

Examination of the cranial nerves and brainstem reflexes has localizing value.  Localization can provide insight into pathophysiology as there are regional differences in susceptibility to various pathologies.

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:  midpositoin, fixed
  • Peripheral III:  usually unilateral, more dilated, fixed
  • Pons: pin point pupils
  • Medulla (lat): Horner’s- preserved response to light
  • Metabolic:  in general met derangements do not affect pupils.  The major exceptions are sympathomimetics and anti-cholinergics which dilate, and opiates which cause pin point pupils.
  • CORNEALS:  V afferent, VII efferent. -pons
  • OCULOCEPHALIC:;          requires levels intact from III- VIII
  • GAG:; IX, X                       -medulla   

MOTOR:

As with the regular neuro exam, the motor exam should start with observation for asymmetric or adventitious movements.  Tone and bulk should be evaluated before strength testing.  If the patient cannot follow commands, motor strength is evaluated in response to noxious stimulation in the form of nail bed compression in each of the four extremities.  Check for asymmetric response as well as movement that localizes to pain, withdraws from pain, or represents posturing.  See GCS below.


POSTURING:

Decorticate:

Extension LE, flexion at elbows/wrists

 

Better prognosis than decerebrate

 

Often without concomitant loss neuro-optho reflexes

 

Usually lesion is above the midbraine

Decerebrate:

Extension LE, extension/pronation/adduction UE

 

Often with neuro-ophtho changes

 

Most commonly lesion at level of midbrain or diencephalon




DTRs:

DTRs are helpful in the same manner as in the non-comatose patient in that lateralized findings imply a focal lesion or etiology.  Upgoing toes (+Babinski) represent corticospinal involvement, but may be seen bilaterally in diffuse processes.

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Glasgow Coma Scale

VERBAL

V5

Oriented

 

V4

Confused

 

V3

Inappropriate words

 

V2

Incomprehensible sounds

 

V1

Nil

EYE

E4

Spontaneous Opening

 

E3

Opens eyes to speech

 

E2

Opens eyes to noxious stim

 

E1

Nil

MOTOR

M6

Obeys motor requests

 

M5

Localizes to noxious stim

 

M4

Withdrawal from noxious stim

 

M3

Abnormal flexion response (decorticate posturing

 

M2

Abnormal extension (decerebrate posturing)

 

M1

Nil

 

 

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