Cure MSA

Country specific patient information

Additional investigations

Non-invasive cardiovascular function tests such as standing blood pressure and heart rate, Valsalva maneuver or heart rate variability should be performed to define the pattern and severity of autonomic dysfunction in MSA. However, these tests may be less helpful for differential diagnosis. Non-specific changes in the EEG are also unhelpful for diagnostic purposes. In patients with urogenital complaints external urethral or anal sphincter EMG frequently shows prolonged and polyphasic muscle potentials consistent with de- and reinnervation of voluntary sphincter muscles. Cranial computerized tomography (CCT) may demonstrate infratentorial atrophy in MSA patients, however, the diagnostic sensitivity is unsatisfactory. In up to 90% of MSA patients MRI reveals typical changes in the striatum, brain stem and cerebellum. In T2 weighted images there is frequently a hyperintense band-like signal adjacent to the posterior lateral putamen. Such increased signal intensity may correspond to activated microglia and is frequently associated with putaminal atrophy and/or hypointensity. The hyperintense periputaminal signal has recently been confirmed as useful diagnostic marker with a sensitivity of 93% as well as specificity of 88%. Hyperintense T2 signal changes are also frequently present in the pons ("hot cross bun" sign). Atrophy-related changes of basal ganglia, brain stem and cerebellum have recently been quantified in patients with parkinsonian disorders using MR volumetry (MRV). The results suggest that, at group level, patients with MSA-P and PSP can be distinguished from those with PD using MRV. Whether MRV improves diagnostic accuracy in individual patients with possible MSA remains to be shown. MR spectroscopy of the lentiform nucleus has been performed in a number of MSA patients revealing reduced N-acetylaspartate as a metabolic correlate of neuronal cell loss. Further studies are required to establish whether MRS is more sensitive to detect striatal pathology in MSA patients compared to conventional MRI.

Functional imaging with SPECT may be helpful in patients with questionable MSA (see table). IBZM SPECT consistently shows reduced striatal dopamine D2 receptor binding in MSA patients. Schwarz and colleagues were able to show that a reduction in striatal IBZM binding predicted unresponsivness to L-dopa in their patients with untreated de-novo parkinsonism. Most of these patients either developed MSA-P or PSP. In contrast, SPECT invesigations using dopamine transporter ligands such as betaCIT appear to be unhelpful in the diagnosis of patients with possible MSA. PET can also contribute to the early diagnosis of MSA, but it is still not widely available.

 

SPECT and PET Findings in MSA

 

Ligand

Binding

Findings

SPECT

123I-Beta-CIT

DAT

reduced striatal DAT-function

 

123I-IBZM
123I-Epidepride

D2 Receptor

reduced striatal binding

PET

18F-DG

Glucose
metabolism

striato-frontal hypometabolism,

brainstem/cerebellum hypometabolism

   

18F-DOPA

DDC-Activity

reduced in putamen and caudate nucleus

 

11C- DTBZ

VMT-2

reduced striatal VMT-2 function

 

11C-SCH23390

D1 Receptor

reduced striatal binding

 

11C-Raclopride
11C-NMSP

D2 Receptor

reduced striatal binding

 

11C-Diprenorphine

Opioid receptor
(non-selective)

reduced in putamen and caudate nucleus

 

Beta CIT, 3-beta-(4-iodophenyl)tropane-2beta-carboxylic acid; DAT, Dopamine transporter; DDC, Dopa-Decarboxylase; DTBZ, dihydrotetrabenazine; FDG, 2-18F fluoro-2-deoxy-D-glucose; IBZM, 2-hydroxy-3-iodo-6-methoxy-N-[(1-ethyl-2-pyrrolidinyl)methyl] benzamide; NMSP, N-methylspiperone; PET, positron emission tomography; SPECT, single photon emission computerized tomography; VMT, vesicular monoamine transporter