According to Suzukis system, it can be classified into six stages:
Stage 1 Narrowing of carotid fork
Stage 2 Initiation of the moyamoya and dilatation of intracranial main arteries
Stage 3 Intensification of the moyamoya and defects of the anterior cerebral artery and middle cerebral artery
Stage 4 Minimization of the moyamoya and defects of the posterior cerebral artery
Stage 5 Reduction of the moyamoya and development of external carotid artery collaterals
Stage 6 Disappearance of the moyamoya and circulation only via external cerebral artery and vertebral arteryMagnetic resonance angiography (MRA) is also useful in diagnosing the disease with good correlation with Suzukis grading system.Proliferation of smooth muscle cells in the walls of the moyamoya-affected arteries has been found to be representative of the disease. A study of six autopsies of six patients who died from moyamoya disease lead to the finding that there is evidence that supports the theory that there is a thickening, or proliferation, of the innermost layer of the vessels affected by moyamoya. These vessels are the ACA (anterior cerebral artery), MCA (middle cerebral artery), and ICA (internal carotid artery). The occlusion of the ICA results in concomitant diminution of the "puff-of-smoke" collaterals, as they are supplied by the ICA.Often nuclear medicine studies such as SPECT (single photon emission computerized tomography) are used to demonstrate the decreased blood and oxygen supply to areas of the brain involved with moyamoya disease.
People with one working copy are genetic carriers of Sanfilippo syndrome. They have no symptoms but may pass down the defective gene to their children. People with two defective copies will suffer from Sanfilippo syndrome. Mechanism
Glycosaminoglycans (GAGs) are chains of sugar molecules. They are found in the extracellular matrix and the cell membrane, or stored in the secretory granules. GAGs are stored in the cell lysosome, and are degraded by enzymes such as glycosidases, sulfatases, and acetyltransferases. Deficiency in these enzymes lead to the four subtypes of MPS III. Diagnosis
Sanfilippo syndrome types A, B, C, and D are considered to be clinically indistinguishable, although mutations in different genes are responsible for each disease. The following discussion is therefore applicable to all four conditions.A urinalysis can show elevated levels of heparan sulfate in the urine. All four types of Sanfilippo syndrome show increased levels of GAGs in the urine; however, this is less true of Sanfilippo syndrome than other MPS disorders. Additionally, urinary GAG levels are higher in infants and toddlers than in older children. In order to avoid a false negative urine test due to dilution, it is important that a urine sample be taken first thing in the morning.The diagnosis may be confirmed by enzyme assay of skin fibroblasts and white blood cells.