Search This Blog

Tuesday, February 2, 2010

Cranial Nerve Examination II

Ok, this time I would like to share with you the technique that I am used to do when it comes to the cranial nerve examination. Like my lecturer used to say, "Every examiner have different techniques of doing it, just adopt the techniques that you are comfortable with and make sure to do it systematically so as not to miss eliciting any sign".

To begin with, these are the cranial nerves, namely:

CN I Olfactory (S)
CN II Optic (S)
CN III Occulomotor (M)
CN IV Trochlear (M)
CN V Trigeminal (B)
CN VI Abducens (M)
CN VII Facial (B)
CN VIII Vestibulocochlear (S)
CN IX Glossopharyngeal (B)
CN X Vagus (B)
CN XI Accessory (M)
CN XII Hypoglossal (M)

S = Sensory
M = Motor
B = Both

There's mnemonics to remember this, you can refer to Wiki or any other sources. But as you go along memorizing these facts, it won't mean a thing if you fail to grasp the concept. I believe that as we practice more on eliciting the signs, it'll be a lot more easier to remember and understand. By the way, this post is just for my revision and not very reliable for educational purposes. Because my blog is not peer-reviewed. And it is way out of my intention to become the reference for medical students or lay people.

Ok let's begin.

1) First, introduce myself and explain that I would like to examine your nerve function. Or just simply say I would like to examine you for a while. Position yourself sitting at the same level, face-to-face to the patient with a distance approximately half meter away.

2) Secondly, ask whether he/she can smell the food that they (I used 'they' to eliminate the gender factor) had for breakfast earlier (CN I)

3) Then, take out mini Snellen chart and ask whether they are literate or not (politely, please). If they are illiterate, use pictorial version of Snellen chart to test for visual acuity. Ask them to hold the chart approximately 30 cm away and to read the words. Usually the examiner would ask you to proceed as this might take some time to accomplish. But sometimes the examiner would not ask us to perform full cranial nerve examination. They might ask to examine one or two of them. They may also ask us to examine patient's visual acuity only. So, if that's the case, ask the patient to do the same procedure, should they failed to do so, change the distance from 30 cm to 15 cm. If they failed to even read the uppermost line, then use "finger counting" technique 15 cm from patient. If finger counting fails, used finger waving. If still unable, take out your torchlight and shine to them. Please refer to Ophthalmology references for the scoring.

4) After that, mention to the examiner that you would also like to ask patient to read from the Ishihara chart for color blindness.

5) Then proceed test for accomodation. Take out your "red-bead-on-a-stick" and tell the patient to look at a far object, then upon instruction, ask them to slowly focus on the "red-bead-on-a-stick". Focus whether the eyes become converged or not. And observe the pupils.

6) Visual field. Ask patient to close one eye using their hand. You also have to close one eye for comparison, assuming that your visual field is normal. If you want to test on the right eye, you close your right eye and compare the field using your left eye. Take out "red-bead-on-a-stick" and held it in between you and patient. Stretch your hand away and tell the patient to inform you once they saw the "red-bead-on-a-stick". But make sure to ask the patient to focus on your face (or nose) and do not move their eyes or face away. (Step 3 to 6 are to test on the CN II - optic nerve)

7) Eye movements. To test for extra-occular muscles. Again, instruct the patient to maintain their face towards you. To be safe (as far as showmanship is concerned), "anchor" their face by putting your fingers on their chin. Then take out "red-bead-on-a-stick" and put it at the center. Ask the patient to follow the movement of the "red-bead-on-a-stick" using their eyes while their face is fixed. Make "H" movement and ask the patient to inform should they see double image of the "red-bead-on-a-stick". As you go along, observe patient's eyes to see whether there is nystagmus present. (CN III, IV, and VI) . More mnemonics - LR6, SO4, the rest of extra occular muscle are supplied by CN III.

8) Take out a cotton wool, make it "pointy" and touch accordingly to respective regions on the face supplied by CN V. Instruct them to mention whether they can feel it and compare the sensation with the reference point, say, on the sternum - "Same or reduced?". Take another 'pointy' cotton wool and test for corneal reflex. Mention to the examiner you would like to do the jaw-jerk reflex. Usually the examiner would ask us to skip. For the motor component, ask them to clench their teeth. Then feel for the temporalis and masseter (muscles of mastication) for any weakness. (CN V)

9) Ask the patient to smile and raised their brows, see whether there is any facial asymmetry. Then ask them to pucker their lips and blow. Press the check gently and see whether there is weakness. Also ask them to close their eyes tightly and then you try to open them using your hands. (CN VII)

10) Pluck your fingers on one of patient's ear (masking effect - but make sure not too loud) and whisper a word on the other. Ask them to repeat the word that has been whispered to them. Mention that ideally I would do proper auditory test as well as Webber's and Ringe's test to test for CN VIII.

11) Ask patient to open their mouth and say "Aah..". Observe the uvula whether it's deviated or not. Then ask them to pull their tongue out and observe whether it's deviated or not. Tongue will deviate towards the site of lesions whilst the uvula is the opposite. (CN X)

12) Gag reflex. Mention to the examiner first, because most of the time you'll be asked to skip it as it is very uncomfortable to the patient. (CN IX and X)

13) Ask the patient to shrug and resist the pressure that you put upon their shoulders. Then ask them to turn their head to one side and try to turn back against your hand. Use the other hand to palpate the strenocleidomastoid muscle of the opposite site to feel whether it's contracting or not. Do the same on the other side afterwards. (CN XII)

14) Finally, said that you would like to complete the examination by doing neurological examination of upper and lower limbs as well.

15) Thank the patient and then present your findings to the examiner (this one you would have to read up and try to find out the possible pathophysiology - haha, reminder to myself...)

That's all for today... Please, do right me if I'm wrong... Thank you in advance... ^^

----------

Reminder to myself: Tutorial with my tutor 2.30 p.m. in the ward. Read up about psychotic disorders and psychopharmacology.


No comments: