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Research

Update on Research into Dystonia at St Vincent's University Hospital and Trinity College Dublin funded by Dystonia Ireland and the Health Research Board.

The Research Team
For the last two years both Dystonia Ireland and the Health Research Board have funded cooperatively a research project in adult onset primary torsion dystonia. The term, Adult Onset Primary Torsion Dystonia (AOPTD), describes the most frequent type of dystonia, which includes a number of conditions including cervical dystonia (spasmodic torticollis), focal hand dystonia (writer’s cramp), blepharospasm, oromandibular dystonia and spasmodic dysphonia.

The principal investigator is Prof Richard Reilly, Department of Neural Engineering at TCD with team members Prof Michael Hutchinson, Dr David Bradley, Dr Okka Kimmich  at SVUH, Dr Robert Whelan in the Department of Neural Engineering at TCD and r Fiona Molloy, Consultant Neurophysiologist Beaumont Hospital.

Recently Dr Sean O’Riordan has joined the team since he took up the post of Consultant Neurologist  at St Vincent’s University Hospital in September 2010. Dr O’Riordan was the first Dystonia Research Fellow at SVUH from 2001-2003 and successfully completed his MD thesis based on his research.

Present Research

Temporal Discrimination
We have established that temporal discrimination is impaired both in people with the different forms of AOPTD and a proportion of their relatives. Temporal discrimination  refers to the ability to see two visual stimuli (flashing lights), or feel two sensory stimuli, (a mild electric twitch) as being separate in time. We test people by asking them to say whether two stimuli are synchronous (appear at the same time) or separated in time. By widening the time interval between the stimuli we can determine the threshold at which the two stimuli are seen as two separate stimuli. This is called the Temporal Discrimination Threshold (TDT). Normally the TDT is less than 50 milliseconds (a twentieth of a second). In people with AOPTD the TDT is greater than this and often 100-200 milliseconds (one tenth to one fifth of a second). This does not have any practical relevance in everyday life, but for research it is very important because we have found that in families where there are two or more people with AOPTD we can find other family members with abnormal TDTs who do not have AOPTD.

We feel that the abnormal TDT is a marker for the carriage of a gene which in a small proportion of people can result in AOPTD but which does not cause any problem in most people who inherit the gene. Probably only one sixth of people who inherit the gene which causes AOPTD actually develop a movement disorder.  We call the prolonged TDT in someone who is a first degree relative of a person with AOPTD an endophenotype.

Endophenotype
The prolonged TDT in unaffected relatives of people with AOPTD (the endophenotype) can be used to discover the gene or genes which cause AOPTD. In order to determine the relevance of the abnormal TDT we are studying patients with AOPTD and their relatives in a special MRI scanner using a technique called functional MRI (fMRI). By using this technique we can determine the region of the brain responsible for the problem with temporal discrimination. Prof Reilly and other members of the team perform a fMRI study over a one hour period on a volunteer to examine brain function while the person in the scanner carries out some simple tests. So far approximstely 50 people have had fMRI scans and this phase of the study should be finished by December 2010.

Searching for genes
For the last five-six years we have been collaborating with Prof. Laurie Ozelius, Bachmann Strauss Professor, Mount Sinai School of Medicine, New York. Prof Ozelius was responsible with clinicians in New York for the discovery of the DYT1 gene in early onset generalized dystonia and has been very active in dystonia research for many years. So far in five Irish families rigorously assessed clinically and by TDT, we have been unsuccessful in highlighting a genetic abnormality. The work goes on; it is hoped, and perhaps expected, that by using a new and difficult technique called exome sequencing that we might be successful in this collaborative effort.

Thank you for all your support.
None of this work, outlined above and resulting in papers published below, would be possible without the unstinting support of people with dystonia and their families. We are conscious of the generous voluntary work which has financially supported this research and the particular help given to the research team by Maria Hickey and her committee who head up Dystonia Ireland. Many people with AOPTD and their relatives have given freely of their personal time and travelled distances to take part in the research; we deeply appreciate their commitment and are deeply grateful to their help in carrying this research through to successful conclusions. We are not there yet, but we are well on the way.

Michael Hutchinson

Research papers from our group on dystonia (2004-2010)

Bradley D, Whelan R, Walsh R, O’Dwyer J,  Reilly R, Hutchinson S, Molloy F, Hutchinson M. Comparing endophenotypes in adult-onset primary torsion dystonia. Movement Disorders 2010;25:84-90.

Bradley D, Whelan R, R Walsh R, Reilly RB, Hutchinson S, Molloy F, Hutchinson M. Temporal discrimination threshold: VBM evidence for an endophenotype in adult-onset primary torsion dystonia. Brain 2009;132; 2327–2335

Walsh RA, Whelan R, O'Dwyer J, O'Riordan S, Hutchinson S, O'Laoide R, Malone
K, Reilly R, Hutchinson M. Striatal morphology correlates with sensory abnormalities in unaffected relatives of cervical dystonia patients. J Neurol 2009;256:1307–1313

Clot F, Grabli D, Cazeneuve C, Roze E, Castelnau P, Chabrol B, Landrieu P, Nguyen K, Ponsot G, Abada M, Doummar D, Damier P, Gil R, Thobois S, Ward AJ, Hutchinson M, Toutain A, Picard F, Camuzat A, Fedirko E, Sân C, Bouteiller D, Leguern E, Durr A, Vidailhet M, Brice A; the French Dystonia Network. Exhaustive analysis of BH4 and dopamine biosynthesis genes in patients with Dopa-responsive dystonia. Brain 2009;132:1753-63

Walsh R, Hutchinson M. Molding the sensory cortex: spatial acuity improves after botulinum toxin treatment for cervical dystonia. Movement Disorders 2007;22:2443-2446.

Walsh R, O’Dwyer JP, Sheikh IH, O’Riordan S, Lynch T, Hutchinson M. Sporadic adult onset dystonia: sensory abnormalities as an endophenotype in unaffected relatives.  J Neurology Neurosurgery and Psychiatry 2007;78: 980-3

O'Rourke K, O'Riordan S, Gallagher J, Hutchinson M.  Paroxysmal torticollis and blepharospasm following bilateral cerebellar infarction. Journal of  Neurology. 2006;253:1644-5

O’Dwyer JP, O’Riordan S, Saunders-Pullman R, Bressman SB, Molloy FM, Lynch T Hutchinson M. Sensory abnormalities in unaffected relatives in familial adult onset dystonia. Neurology 2005;65:938-940

O’Riordan S, Ozelius LJ, de Carvalho Aguiar P, Hutchinson M, King M, Lynch T. Inherited myoclonus-epilepsy: further evidence of an association? Movement  Disorders  2004;19:1456-59

O’Riordan S, Raymond D, Lynch T, Saunders-Pullman R Bressman SB, Daly L, Hutchinson M. Age at onset as a factor in determining the phenotype of primary torsion dystonia. Neurology 2004;63:1423–1426

O'Riordan S, Lynch T, Hutchinson M. Familial adolescent-onset scoliosis and later segmental dystonia in an Irish family. Journal of  Neurology 2004;251:845-8

O'Riordan S, Hutchinson M. Cervical dystonia following peripheral trauma--a case-control study. Journal of Neurology. 2004;251:150-5

Prizes Received for Dystonia Research.
1) Richard Walsh; Uschi Tschabitscher Prize for Young Neurologists at the European Federation of Neurological Societies, Glasgow, 2006.
R Walsh, JP O’Dwyer, IH Sheikh, S O’Riordan, T Lynch, M Hutchinson. Spatial discrimination thresholds in unaffected relatives of patients with sporadic adult onset primary torsion dystonia: further evidence of an endophenotype.

2) David Bradley; Uschi Tschabitscher Prize for Young Neurologists at the European Federation of Neurological Societies, Florence, 2009.
D Bradley, R. Whelan, R Walsh, RB Reilly, S Hutchinson, F Molloy, M Hutchinson. Temporal Discrimination Thresholds in familial AOPTD Pedigrees-use of a new endophenotype.

3) David Bradley; Harold Miller Prize for best platform presentation at the Irish Neurological Association meeting in Dublin, 2009.
D Bradley, R. Whelan, R Walsh, RB Reilly, S Hutchinson, F Molloy, M Hutchinson. Temporal Discrimination Thresholds in familial AOPTD Pedigrees-use of a new endophenotype.

4) Drs David Bradley and Richard Walsh won the Lundbeck Neuroscience Bursary, in conjunction with the Irish Institute of Neuroscience, in December 2007 in recognition of their research projects and were awarded €10,000 which was spent on new equipment for the laboratory.

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