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					Block 4 Case 1                                                                                                    Alex Teeters
Wednesday Objective: Glasgow Coma Scale and Pupil Size                                               Wednesday, March 14, 2007
What is the Glasgow coma scale? What is the significance of different pupil sizes on page 2 and 6.

Glasgow Coma Scale
 The Glasgow coma scale (GCS) is scored between 3 and 15
        o 3 is the worst and 15 is the best.
 It grades coma severity according to 3 parameters:
        o Best Eye Response (E)
        o Best Verbal Response (V)
        o Best Motor Response (M)
 The interpretation of the score is as follows
        o 13-15: Mild Brain Injury
        o 9-12: Moderate Brain Injury
        o 3-8: Severe Brain Injury. “Patients with a GCS of 8 or less usually
           require endotracheal intubation to protect the airway.”
 Over 85% of patients with aggregate scores of 3 or 4 die within 24 hours.
 The GCS is helpful in determining the prognosis of a coma patient, but not for
   the diagnosis of coma.
 Since interventions such as intubation or sedatives can interfere with the results
   of the GCS, the GCS should be obtained on admission.
 The GCS is the most utilized “level of consciousness” scale.

Pupil Size & Reactivity
Page 2: The right pupil was 3 mm and responsive to light. The left pupil was 4
mm and responsive to light.
Page 6: The right pupil was dilated to 4 mm, but reacted to light. The left pupil
remained fixed and dilated to 6 mm. Three hours later, his right pupil was 3.5 mm,
and his left pupil was 4 mm; both reactive to light.
Page 7: PERRLA, both pupils were 2 mm.

   “In a brightly illuminated examining room, normal pupils are about 3 mm in
    diameter in adults.”
   Miosis defined to be pupillary constriction to less than 2 mm and failure to dilate in the dark.
   Mydriasis is pupillary dilation of more than 6 mm and failure of the pupils to constrict with light. Mydriasis is an
    accompaniment of coma. Specifically, it can be caused by:
        o Iridocyclitis (inflammation of both iris and ciliary body)
        o Midbrain lesions or hypoxia
        o CN III damage – Recall that CN III carries parasympathetic input from the Edinger-Westphal nucleus that
             controls the pupillary constrictors. Thus loss of CN III innervation will result in uncompensated sympathetic
             input which will lead to dilation.
        o Drug Abuse
   Anisocoria is when the pupil sizes aren’t equal. It can be caused by:
        o Congenital (~20% of healthy people have a <1 mm difference in pupil size, but reflexes are normal)
        o Unilateral sympathetic or parasympathetic pupillary pathway destruction
   Unilateral disorders of pupillary constriction can be seen with:
        o Local disease of the iris (trauma, iritis, glaucoma)
        o CN III compression (tumor, aneurysm)
        o Optic nerve disorders (optic neuritis, multiple sclerosis)
Block 4 Case 1                                                                                                              Alex Teeters
Wednesday Objective: Glasgow Coma Scale and Pupil Size                                                         Wednesday, March 14, 2007
   A unilaterally dilated, unreactive pupil (Page 6 of our case) in a comatose patient may be caused by herniation of the
    ipsilateral temporal uncus through the tentorium, which compresses CN III ipsilaterally.

My Opinion: The “brain cyst” may have caused compression of CN III that led to his mild mydriasis seen on page 6. CN
III compression might also explain his anisocoria noted on that page as well. The slight difference in pupil size noted on
page 2 and later on page 6 could be caused by CN III compression.




Marked Anisocoria

Sources
1. Up To Date: “Anoxic brain injury: Assessment and treatment”
2. Up To Date: “Stupor and coma in adults”
3. Harrison’s Internal Medicine. Chapter 357. Concussion and Other Head Injuries. (Access Medicine)
4. Sternbach, G. L., “The Glasgow Coma Scale” Journal of Emergency Medicine. Volume 19, Issue 1. July 2000. Pages 67-71.
5. Mosby’s Guide to Physical Examination: 6th Edition. Pages 292, 307 - 308.
6. Lange Neurology. Chapter 4. Disturbances of Vision. (Access Medicine)
7. Principles of Critical Care. Chapter 67. Coma, Persistent Vegetative State, and Brain Death. (Access Medicine)
8. Emergency Medicine Atlas > Part 1. Regional Anatomy > Chapter 2. Ophthalmologic Conditions > Anisocoria Picture (Access Medicine)

				
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