brought to you by the nerve stimulation experts at Neurosign

June 20, 2019

Petroclival meningioma



These meningiomas are difficult to access when trying to make a total clearance. They are extensive tumours, invading spaces in the brain and compressing the brainstem and cranial nerves. The nerves may be pushed posteriorly, laterally, on the surface, or may even be encased in the tumour. The surgeon is using a retro-sigmoid approach for this patient, who has a 7cm tumour in the cerebellopontine angle, showing evidence of a compressed brainstem.

The patient has loss of sensation on the affected side in the face, and difficulty in chewing and swallowing. The patient tends to bite the tongue and drools. Clinical indications suggest trigeminal, facial, and lower cranial nerve involvement.

The patient is a young adult, so as much of the tumour a possible needs to be removed.

I am monitoring V, VII, IX, X and XII using my usual montage.

After opening the dura and retracting the cerebellum, IX, X and XI were identified and stimulated. The facial gave spontaneous responses but has yet to be stimulated.

Facial has now been stimulated – it is passing through the tumour, although fortunately it is close to the capsule and the tumour is simply peeling away from the nerve.

CUSA is being used to debulk the tumour.

There has been a lot of activity from the facial as the CUSA is used, because the facial nerve is now free of tumour but the CUSA has to pass it to reach the tumour behind.

Trigeminal nerve has started firing – surgeon alerted after 1 large response. After some careful dissection, surgeon has identified Vth nerve visually and is continuing to debulk tumour.

Trigeminal is now more clearly visible and surgeon has stimulated it at 0.4m and confirmed it as trigeminal.

Surgeon has removed 95% of the tumour and has decided to leave the remainder as it is sticking to the brainstem. Facial, trigeminal and lower cranial nerves all stimulate, although the facial is weaker at the brainstem than at the porus. It is interesting to see the nerves – they all look remarkably ‘normal’, even though the facial and trigeminal were surrounded by tumour, compared to acoustics where the nerves often look crushed and fragile.

Surgeon is closing.