What is striking is that this man has facial asymmetry. The first challenge for the student is to decide which side is the abnormal side and which side is normal.
The photo above shows a flattened or loss of right nasolabial fold indicating the facial abnormality is on the right.
If you look closely enough, there is also loss of wrinkles over the right forehead. This is an important clue to show that this is a lower motor neuron (LMN) lesion involving the facial nerve (CN 7).
Once you suspect the diagnosis of CN 7 LMN lesion, then you'll need to quickly identify the possible causes. I would like highlight 5 common causes of LMN CN 7 which may appear for the exams.
1. Mononeuritis - connective tissue disorders/ diabetes
2. Parotid gland swelling
3. Ramsay Hunt Syndrome
4. Cerebellopontine angle tumours
5. Bell's palsy (idiopathy)
If you look closely at the photo above, you may be able to appreciate a bump protruding outwards (red arrow) from the right angle of mandible (compared to the left angle which is concave).
This patient has a right parotid gland tumour, which has compressed on the right facial nerve resulting in lower motor neuron right facial nerve palsy.
Once the diagnosis is established and the cause identified, next and last step is to try identify possible complications of the diagnosis. A common problem with people suffering from LMN facial nerve palsy is the inability to close the ipsilateral eye lids completely. This can result in excessive drying of the conjunctiva and cornea leading to red and irritated eyes, a condition called exposure keratitis. Prolonged irritation and drying can cause corneal scarring which may impair vision. So whenever students encounter a LMN facial nerve palsy case, always look out for exposure keratitis after the aetiology of the LMN facial nerve has been identified.
Always keep this triad in mind when approaching any case: Diagnosis - Aetiology - Complication....This will ensure your assessment of the patient is complete.
CCE.
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