An Italian research team has put out a research paper comparing TCR (trigemino-cervical reflexes) in MSA and PSP.
TCRs are “electromyographic responses induced by electrical stimulation of the trigeminal nerve and recorded in the neck muscles.” Neurologically-normal people have TCRs in response to painful stimuli in the face; the head visibly retracts.
A research paper published in 2008 from the same Italian team showed that TCRs were absent in PSP, probably due to brainstem degeneration. TCRs were detected “in patients with PD, albeit showing a longer reflex latency than that found in healthy controls… These results suggest that absence of TCRs may be useful in supporting the diagnosis of PSP and may represent a potential tool for distinguishing PSP from other parkinsonian syndromes.”
Since MSA and PSP can look alike, the team decided to “investigate the usefulness of TCRs in differentiating PSP from MSA.” The authors note that the “differential diagnosis of these two conditions can be difficult,
especially when specific neurological signs, such as dysautonomy or vertical gaze palsy, are not obvious.”
The researchers compared 10 people with a clinical diagnosis of MSA-P to 10 people with a clinical diagnosis of PSP. (The neurophysiologist testers were unaware of the clinical diagnoses.) They found that all 10 patients with a clinical diagnosis of MSA-P demonstrated TCRs, and all 10 patients with a clinical diagnosis of PSP has no TCRs. “An important result of the comparison of the two groups of patients in our study is that no differences were found in terms of disease duration and severity.” The authors believe that PSP and MSA-P have different levels of brainstem degeneration.
The authors conclude: “Trigemino-cervical reflex recording is a rapid neurophysiological method, which could assist in the differential diagnosis between PSP and MSA-P.” The authors call for another study to include MSA-C patients.
This finding will be of interest to the PSP folks: “we found that PSP patients have high pain thresholds, although this feature cannot differentiate these subjects from MSA patients.” The authors speculate this is due to dysregulation of the pain processing contro.”
One weakness of the study is that these are clinical diagnoses. As the authors point out, PSP and MSA can be confused.
I’ve copied the abstract below.
Clinical Neurophysiology. 2011 Mar 9. [Epub ahead of print]
The contribution of trigemino-cervical reflexes in distinguishing progressive supranuclear palsy from multiple system atrophy.
Serrao M, Di Fabio R, Bartolo M, Perrotta A, Tassorelli C, Coppola G, Davassi C, Padua L, Sandrini G, Pierelli F.
Department of Medical and Surgical Science and Biotechnology, “Sapienza” University of Rome ICOT – Polo Pontino, Latina, Italy; Rehabilitation Centre Policlinico Italia, Rome, Italy.
OBJECTIVE: Trigemino-cervical reflexes (TCRs) are electromyographic responses induced by electrical stimulation of the trigeminal nerve and recorded in the neck muscles. Trigemino-cervical reflexes are detectable in Parkinson’s disease, whereas they are absent in progressive supranuclear palsy (PSP), an atypical parkinsonism associated with brainstem degeneration. To date, no study has investigated TCRs in multiple system atrophy (MSA), another atypical parkinsonism associated with brainstem involvement, which resembles PSP.
METHODS: To understand whether TCRs are helpful in differentiating PSP from MSA, we compared the TCRs recorded in 10 PSP patients with those obtained from 10 patients diagnosed as having probable MSA, parkinsonian type (MSA-P).
RESULTS: Trigemino-cervical reflexes were not recorded in any of the PSP patients, while they were clearly detectable in all the MSA-P patients.
CONCLUSIONS: Trigemino-cervical reflex recording is a rapid neurophysiological method, which could assist in the differential diagnosis between PSP and MSA-P.
SIGNIFICANCE: This study further improves our understanding of the different neuronal functioning of extrapyramidal disorders. TCRs monitoring may be useful to support the diagnosis of atypical parkinsonisms especially when clinical evidence is uncertain.
Copyright © 2011. Published by Elsevier Ireland Ltd.
PubMed ID#: 21396886 (see pubmed.gov for this abstract only)