Autonomic testing to differentiate MSA and PD

This is a Mayo Rochester study of 10 people with a clinical diagnosis of Parkinson’s Disease (including the presence of all three cardinal features — resting tremor, bradykinesia, and rigidity) and 9 people with a clinical diagnosis of multiple system atrophy (including orthostatic hypotension or urinary incontinence, parkinsonism responding poorly to levodopa or cerebellar ataxia).

The authors note that specific autonomic tests are not part of the diagnostic criteria for multiple system atrophy (MSA).

The authors state:

“Our results are in keeping with previous data showing more widespread anhidrosis on TST [thermoregulatory sweat test] among MSA patients, and that this degree of anhidrosis distinguishes this disorder from PD. Similarly overall autonomic dysfunction, as indicated by the CASS score, was more severe and widespread in the MSA group versus the PD group supporting similar data from previous studies. These findings continue to support our previous assertions that the severity and distribution of autonomic dysfunction in MSA patients are useful clinical additions in distinguishing this disorder from PD.”

The authors conclude that the “thermoregulatory sweat test provides the best distinction between MSA and PD.” They also like the autonomic reflex screen (to generate the CASS score).

The authors also note that this study, in contrast to previous studies, found that I123 MIBG myocardial scintigraphy did not differentiate PD from MSA. However, they believe that MIBG may be a useful part of the testing program.

The abstract is below.

Robin

Journal of the Neurological Sciences. 2012 Mar 13. [Epub ahead of print]

The role of autonomic testing in the differentiation of Parkinson’s disease from multiple system atrophy.

Kimpinski K, Iodice V, Burton DD, Camilleri M, Mullan BP, Lipp A, Sandroni P, Gehrking TL, Sletten DM, Ahlskog JE, Fealey RD, Singer W, Low PA.
Department of Clinical Neurological Sciences, London Health Sciences Centre, University of Western Ontario, London, ON, Canada.

Abstract
Differentiation of idiopathic Parkinson’s disease (PD) from multiple system atrophy (MSA) can be difficult. Methods devised to help distinguish the two disorders include standardized autonomic testing and cardiac imaging with iodine-123 meta-iodobenzylguanidine myocardial scintigraphy.

MSA patients had more severe adrenergic and overall autonomic dysfunction when compared to control and PD patients.

Area of anhidrosis on thermoregulatory sweat test was greater in MSA (67.4±12.42, p<0.001) versus PD patients (area of anhidrosis, 1.7±2.96).

Postganglionic cardiac sympathetic innervation (iodine-123 meta-iodobenzylguanidine) expressed as heart to mediastinal ratio was significantly lower in Parkinson’s disease patients (1.4±0.40, p=0.025) compared to controls (2.0±0.29), but not in multiple system atrophy (2.0±0.76).

These findings indicate that autonomic dysfunction is generalized and predominantly preganglionic in multiple system atrophy, and postganglionic in Parkinson’s disease.

In our hands the thermoregulatory sweat test provides the best distinction between MSA and PD. However further confirmatory studies using larger patient numbers are required. Currently a combination of clinical judgment and autonomic testing is recommended to help differentiate MSA and PD.

PubMed ID#: 22421352 (see pubmed.gov for this abstract only)