Question about assessing neurologic function???

[macbook00]

Can somebody helping me with this - is there any good online sources or any good review papers online that can give me information about assessing brain function in patients post-cardiac arrest? I am wondering what the specific guidlines are regarding prognosis and how we are supposed to figure out their brain function (if any parts and if so which ones have been damaged due to anoxia)? I have looked all over, maybe I am not searching correctly, but have found no clear answer. Please help! I really appreciate it.

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[SomeDoc]

Can somebody helping me with this - is there any good online sources or any good review papers online that can give me information about assessing brain function in patients post-cardiac arrest? I am wondering what the specific guidlines are regarding prognosis and how we are supposed to figure out their brain function (if any parts and if so which ones have been damaged due to anoxia)? I have looked all over, maybe I am not searching correctly, but have found no clear answer. Please help! I really appreciate it.

In general, you should consider all areas and associated functions (including motor/sensory homunculus) supplied by:

Ant. cerebral artery
Post. cerebral artery
Middle. cerebral artery
Circle of willis (and branches other than the above; ie. AICA, PICA, basilar, vertebral, spinal a.'s)

Memory function, speech (broca's, wernicke's areas, arcuate fasciculus).

That should give you a rough guideline of where to start.

Since anoxia is due to cardiac arrest as opposed to focal ischemic attack due to thrombus/embolus, decline in function may be more global in nature.

 

[macbook00]

In general, you should consider all areas and associated functions (including motor/sensory homunculus) supplied by:

Ant. cerebral artery
Post. cerebral artery
Middle. cerebral artery
Circle of willis (and branches other than the above; ie. AICA, PICA, basilar, vertebral, spinal a.'s)

Memory function, speech (broca's, wernicke's areas, arcuate fasciculus).

That should give you a rough guideline of where to start.

Since anoxia is due to cardiac arrest as opposed to focal ischemic attack due to thrombus/embolus, decline in function may be more global in nature.

Oh okay, so how do we test these individual areas? Especially if a person is on a ventilator?? An EEG? How about more manual tests - like response to sounds, pain, touch - what parts of the brain do those tests?

 

[SomeDoc]

Oh okay, so how do we test these individual areas? Especially if a person is on a ventilator?? An EEG? How about more manual tests - like response to sounds, pain, touch - what parts of the brain do those tests?

Sounds: medial geniculate nucleus of thalamus, CN VIII
Pain and temp: VPL, VPM nuclei of thalami, spinothalamic tracts
Touch (proprioception, point discrimination, vibratory sense): VPL nuclei of thalamus, dorsal spinocerebellar tracts/cerebellum.

Regarding how you would test the above in a non-ambulatory patient, you would do as you would in a normal test with obvious limitations due to positioning and/or impairment of consciousness (ie if the patient is not conscious, you wont be able to assess his/her responsiveness to sound.)

 

[macbook00]

So lets say someone is on a ventilator and we want to figure out if they have enough brain function to breath on their own - is there any test (besides reducing ventilator dependency and seeing how they respond) to figure this out? Sorry I haven't had neuroanatomy yet so I have no basis to know. But I guess I wanted to know if we can actually test the part of the brain specifically to know how much activity is there??

 

[BigRedBeta]

Your ICU scales like GCS and APACHE II are good places to start.

I'm vaguely remember my school having a lecture in neuroscience during the first year about brain death...but I don't remember much about it.

I'd check the neurosurg/neurology literature for "brain death determination"

 

[anarchron]

So lets say someone is on a ventilator and we want to figure out if they have enough brain function to breath on their own - is there any test (besides reducing ventilator dependency and seeing how they respond) to figure this out? Sorry I haven't had neuroanatomy yet so I have no basis to know. But I guess I wanted to know if we can actually test the part of the brain specifically to know how much activity is there??

There's a special part of the brainstem that controls autonomic motor functions such as breathing, gut motility and heart rate. It's called the Caudal Reticular Formation. It's mainly an anatomical/histological classification so I doubt that there would be anyway to measure the brain activity at that part.

 

[mlw47]

If you're not looking for a clinical picture of the person's specific disability, in the literature the standard post-arrest neurological outcome that's measured is a functional score: the Cerebral Performance Category Score.

CPC 1: Good cerebral performance. Conscious and able to work.
CPC 2: Moderate disability that affects activities of daily living.
CPC 3: Severe disability. Dependent on others for daily living.
CPC 4: Coma or PVS.
CPC 5: Brain dead.

A CPC of 1 or 2 is considered a favorable outcome. There's a separate scoring algorithm for pediatric CPC. It was developed by some folks out at Pitt a while back. It's all throughout the EM literature, just do a quick search for neuro outcomes and arrest.

 

[anarchron]

Mini-mentals FTW!

 

[EMCC]

There are a few ways to determine brain activity post-cardiac arrest. The simplest way is to examine the patient.

Since you have not had neuro yet, hopefully this will be helpful. The bedside tests worth performing are to check the brainstem reflexes. The most important of these are the corneal reflex, the gag reflex, the cough reflex, and spontaneous respirations. This is all predicated on having an exam with a GCS (Glascow Coma Scale) of 3T (the T stands for intubated--"tubed"). We test these reflexes is because these reflexes originate within the medulla--the most primitive part of the brainstem (which is itself very primitive). You can test respirations by either turning down the ventilator, or by performing an apnea test. Each state varies in what is defnined as a positive apnea test.

In addition, you can perform some imaging studies as well. The most specific and sensitive test is the brain flow scan. This test uses a radionucleide to see how much uptake neurons have. If there is no uptake--the patient is braindead. If there is uptake--even minimal, then the patient is not dead.

Basically, you can declare someone brain dead if two exams seperated by time show no brainstem reflexes, or if you have a negative brain flow scan. The most important criteria, however, is that the patient not be on any medications that can reduce cerebral metabolism. Usually, this medication is pentobarb/phenobarb.

Any other questions? Let me know.

 

[supersleuthMD11]

Also, to address the issue of testing audotory function in a patient who is not conscious but does have brainstem reflexes (doll's eye maneuver, etc) you can use auditory brainstem response testing, in which the response of brainstem auditory centers (MGN, sup olivary nucleus, etc). is evaluated after presentation of a click-sound to the patient.