Initial Workup

• How is the diagnosis of Moyamoya made?

• Who will need surgery ie cerebral revascularization/EC-IC bypass operation?

• What is EC-IC bypass?

• What is indirect revascularization?

• The Zürich-KISPI pre- and post-surgical evaluation Protocol

• The logistics of a single KISPI-hospitalisation is as follows

How is the diagnosis of Moyamoya made?

The important thing is to understand and pick the initial symptoms up and to insist on further evaluation. Usually several years are lost because of misdiagnosis. Therefore if your child s sffering from continuous headaches, migraines, episodes of weakness in a limb, sensory disturbances, visual disturbances, speech problems go to your pediatrician and let him/her refer you to a neurologist who will perform a clinicla exam and initiate further tests together with referring you to a MM specialist:

1. The first investigation performed is an MRI/MRA exam where the diagnosis of Moyamoya can be made on the bases of previous infarcts and Mm vessels.
2. The 6-vessel cerebral angiography is the gold standard. This will confirm the diagnosis.
3. To evaluate the perfusion/blood flow reserves in the brain a PET scan will follow.

Depending on the results of these investigations the need of surgical revascularization will be established.

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Who will need surgery ie cerebral revascularization/EC-IC bypass operation?

A child who is symptomatic, has MM on MRI and angiography and decreased perfusion reserves on PET will need surgery. The goal of surgery is to prevent further strokes and enable the child to lead a normal life without any mental and physical handicap thereafter.

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What is EC-IC bypass?

EC-IC bypass means an extracranial to intracranial bypass of two arteries.

Here an anastomosis i.e connection is made between an artery supplying the scalp (the STA: superficial temporal artery) to an artery lying on the surface of the brain (cortical artery branch of the MCA or ACA or PCA). This enables blood to flow from the STA, bypassing the MM obstruction, into the brain that is not getting enough blood flow resulting in strokes.

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What is indirect revascularization?

If the STA is too small or if the cortical branch is too small then an indirect revascularization is performed by either placing muscle (the temporalis muscle) or inverting the dura (brain covering) onto the brain directly. This allows for formation of new vessels over a period of months.

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The Zürich-KISPI pre- and post-surgical evaluation Protocol

Children with Moyamoya angiopathy are referred to us from all across Europe. To plan for surgery a number of presurgical examinations have to be performed before the decision of the most effective type and number of surgical procedure is made.

These investigations include a routine neurological examination, a routine blood test, ECG and if necessary a chest x-ray. The special investigations include an MRI/MRA scan, 6 –vessel cerebral angiography, a water-PET (H215O)-PET examination. Depending on the extent of disease on MRI and angiography and the extent of perfusion deficits the number of revascularization procedures to be performed is decided. We always advocate and perform a direct EC-IC bypass or end to side anastomosis of two vessels/arteries mainly the superficial temporal artery STA and a cortical vessel of either the anterior ACA, middle MCA or posterior PCA cerebral arteries. If these vessels are of too small a calibre an indirect revascularisation using the dura- or arteriosynangiosis technique is performed.

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The logistics of a single KISPI-hospitalisation is as follows:

Children are admitted to the Kinderspital, Steinweisstrasse, Zürich on the PSU/PSA ward. Admissions are organised for a Monday/Friday and the preoperative examinations are carried out on the following days. Depending on the number of bypass operations to be performed the total hospital stay varies from 7-10 days to upto 2.5 weeks. Once the child has been successfully operated with an unremarkable postoperative in-patient stay a follow-up is carried out usually at 6 months with repeat clinical and angiography and PET examinations in Childrens hospital.

Children who have reached puberty will require the same follow-up (clinical evaluation, MRI, angio, PET) again. Also a repeat MRI/MRA, angiography and PET examinations will be performed only if there is a steady, continuous increase in repeated TIAs occurrence of any new symptomatology.