LMN 7th CN Palsy

LMN 7th CN palsy is commonly shown up in PACES neurology station.
As a PACES candidate, it is not good enough to just diagnose the condition but you have to search for the cause! (Still remember the 4C rule?)

The differential diagnoses are:

-Ramsay Hunt syndrome

-Cerebellopontine angle tumour

-Parotid tumour

-Trauma/surgery

-Middle ear disease

-Pontine lesion eg stroke, multiple sclerosis

-mononeuritis multiplex

-Bell's palsy(diagnoses of exclusion)

General inspection will reveal facial asymmetry.
First, confirm the side of facial weakness by asking patient to raise eyebrows, shut eyes tight, smile and show teeth and blow up cheeks.
Secondly, shine your torch to the ear of the affected side to look for vesicles of herpes zoster. This is to show that you are looking for Ramsay Hunt syndrome as the cause.

Third, look for scar over the parotid gland and palpate for parotid tumour.

Proceed to check the eye movements particularly looking for nystagmus and abducens palsy over the affected side.

Then, check the corneal reflex and facial sensation. Remember loss of corneal reflex is an early sign of cerebellopontine lesion.

Remember the Rinne's and Weber's test.

Lastly, checking for cerebellar signs and pronator drift (pontine lesion).

Just say you want to complete to the examination by doing a otoscope, fundoscopy(MS/DM/SLE) and 9th/10th/11th/12th CN(probably not required unless the cerebellopontine angle tumour is massive!)