L LMN 7th CN palsy

One of the most common cranial nerve examination in MRCP and Medical student exams !

Look at this patient's face and proceed with the necessary.

I remember that when I was practising with eMRCPian before my MRCP PACES exam, he used to tell me that do the necessary and don't examine the cranial nerves from I to XII which would normally be done by most medical students.

It is obvious from inspection that there is loss of nasolabial fold on the left.
Start with cranial nerve VII

• Loss of wrinkling of the forehead, unable to close the L eye tightly, unable to blow the cheeks, mouth deviated to the right on showing the teeth
• Look for Bell's phenomenon - upward movement of eye and incomplete closure of eyelid when the patient attempts to shut the eyelids
  

After establishing that it is LMN 7th CN palsy, next we have to see whether other cranial nerves are involved.

• Check the III, IV, VI CN by checking the eye movement, a CP angle tumour can extend to involve these cranial nerves or in cases of NPC where you get multiple CN involvement
• Check the V cranial nerve esp corneal reflex (remember that afferent is V and efferent is VII for corneal reflex)
• Check the VIII cranial nerve - will be involved in CP angle tumour
• You can check other cranial nerves quickly - IX,X,XI,XII
• It won't be necessary to check the CN I or II

Next, we need to establish the cause if it is solely the VII LMN 7th CN involved.

• Shine a torch into the ear(the site of the 7th CN palsy) to look for vesicles in Ramsay Hunt syndrome
• Examine the parotid glands for parotid enlargement (remember that the 5 branches of the 7th nerves comes out here - Used to remember "Clincal examination by Talley, O' Connor" which mentioned Two Zebras Bit My Car - Temporal, Zygomatic, Buccal, Mandibular, Cervical)
• Check for lymph nodes enlargement - NPC
• Check also for cerebellar signs of the upper limbs (CP angle tumour)

Offer to check the taste of the anterior 2/3 of the tongue and to look for hyperacussis.

For medical students, try to remember the pathway of the 7th cranial nerve and the branches of it.