CC5: Coma

Question 1

List the 7 exams to do during a COMA examination

Answer 1

1 - Neurological Exam of Altered Consciousness
2 - Vital Signs
3 - Respiratory Pattern
4 - Level of Consciousness
5 - Pupils
6 - Ocular movements
7 - Motor Responses

Question 2

There is a Neurological Exam of Altered Consciousness. What are the 4 levels of consciousness?

Answer 2

1 - Normal - no external stimulation needed to be awake

2 - Somnolent -external stimulation will lead to normal wakefulness

3 - Obtunded -external stimulation will not lead to normal wakefulness

4 - Coma -No wakefulness

Question 3

We talked about 3 respiratory patterns. Describe them and state where the lesion may be.

Answer 3

1 - Cheyne-stokes respiration: abnormal pattern of breathing characterized by progressively deeper and sometimes faster breathing, followed by a gradual decrease that results in a temporary stop in breathing called an apnea. Lesion in diencephelon

2 - Central neurogenic hyperventilation: abnormal pattern of breathing characterized by deep and rapid breaths at a rate of at least 25 breaths per minute. Increasing irregularity of this respiratory rate generally is a sign that the patient will enter into coma. Lesion in midbrain, but lower center in pons is working which is responsible for producing the deep breaths at regular pace.

3 - Apneustic respirations: abnormal pattern of breathing characterized by deep, gasping inspiration with a pause at full inspiration followed by a brief, insufficient release. Lesion in pons, but medulla is still working.

Question 4

What effect will a lesion caused by metabolic problems (due to drugs) have on the pupils?

Answer 4

The pupils will be small, but reactive to light.

Question 5

What effect will a lesion in diencephelon have on pupils?

Answer 5

The pupils will be small, but reactive to light.

Question 6

What effect will ioslated lesion in the tectum (superior and inferior colliculi in midbrain) have on pupils?

Answer 6

The pupils will be in mid-position, and not reactive to light.

Question 7

What effect will lesion of the CN III have on pupils?

Answer 7

There will be no direct pupillary light reflex, but there will be a consensual response.

Question 8

What effect will lesion in the midbrain have on pupils?

Answer 8

midposition, no pupillary light response.

Question 9

If someone has big pupils, and no coma, it may suggest pathology where?

Answer 9

CN III

Question 10

If someone has big pupils, and coma, it may suggest pathology where?

Answer 10

midbrain

Question 11

The vestibulocular reflex aka oculocephalic aka occulovestibular reflex –> explain it.

Answer 11

when head turns right, the eyes will look left, and then there will be a quick right nystagmus to get back to rest.

Question 12

What are the 2 different motor responses in light coma, and what do these responses tell us about the nature of the pathology?

• light coma is present when reflex motor response (i.e., decorticate and decerebrate posturing) can be elicited by noxious stimulation. In deep coma there is no response.

Answer 12

1) Decorticate Posturing – lesion above red nucleus
- abnormal flexor response of arm w/ extension of the legs
- flexion of upper extremities
- extension of legs
- legs internally rotated and plantar flexion
- spastic hemiparesis due to disconnections of cortex & motor centers

2) Decerebrate Posturing – lesion below red nucleus
- abnormal extensor response of of arm & leg
- extension of trunk & neck
- clenching of jaws
- stiff extension of limbs
- internal rotation of amrs
- plantar flexion of feet.

Question 13

What are some symptoms associated with bilateral diencephalic stage (diencephalic coma)?

Answer 13

• Cheyne-stoke respiration (crescendo-decrescendo pattern of respirations which is punctuated by periods of apnea of variable length)
• small pupils, reactive to light (b/c midbrain is fine)
• vestibulocular reflex is fine (pons is fine)
• motor responses = decorticate b/c diencepheon is above the red nucleus which is located in the midbrain

Question 14

What are some symptoms associated with bilateral midbrain stage coma?

Answer 14

• central neurogenic hyperventilation (deep breaths at regular pace) -midbrain lesion, sparing pons.
• pupils midposition, unresponsive to light (characteristic of midbrain lesion)
• oculovestibular reflex is impaired due to problems w/ CN III since it resides in midbrain
• motor responses = decerebrate (lesion is below red nucleus)
• so level at midbrain, pt may not wake up.

Question 15

What are some symptoms associated with bilateral pontine stage coma?

Answer 15

• eupneic breathing (normal, good, unlabored ventilation)
• pupils midposition, no light reflex (problems w/ CN III -midbrain)
• oculovestibular response is impaired so problems with CN III and CNIV
• no motor responses (b/c pons is affected where vestibular nuclei are)

Question 16

What are some symptoms associated with unilateral diencephalic stage?

Answer 16

• might have normal breathing or cheynes stokes
• small pupils, good light reflex
• oculovestibular is fine
• motor = asymmetrical response (contralateral side affected), + babinski reflex

Question 17

What are some symptoms associated with Late third nerve stage?

*this needs to be corrected asap.

Answer 17

• uncus can push on CN III
• regular sustained deep breathing
• one pupil does not respond; consensual is intact (so part of midbrain is working)
• impaired oculovestibular response
• motor -decorticate on one side and decerebrate on another.