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Fahn-Marsden-Rating-Scale

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Fahn–Marsden Rating Scale

G Bernard,Montreal Children’s Hospital,Montreal,QC,Canada S Chouinard,University of Montreal,Montreal,QC,Canada

R Saunders-Pullman,Albert Einstein College of Medicine,New York,NY,USA

ã2010Elvier Ltd.All rights rerved.

Glossary

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Dystonia –Sustained muscle contractions of agonists and antagonists causing involuntary twisting movements and postures.

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Reliability –Consistency of the asssment or measurement of a given tool (e.g.,a scale),at different times or by different evaluators.

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Validity –Degree to which a test (e.g.,a scale)measures what it is intended.

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Definition and History

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Dystonia is a hyperkinetic movement disorder character-ized by sustained twisting and posturing mo

vements,which may affect single or multiple body areas.While there are characteristic electrophysiologic features of dystonia,such as muscle agonist–antagonist cocontrac-tion,the do not yet allow quantification of verity of dystonia in different body sites.Further,the features of dystonia are not static and vary according to activity.In order to better characterize the clinical cour,and to asss the efficacy of treatments,scales to capture both the verity of the dystonia (including the dynamic fea-tures)and the functional disability of the dystonia are needed.Scales may encompass dystonia affecting all body sites,such as the Fahn–Marsden (F–M)rating scale,which may be ud for generalized,gmental,or focal dystonia,or may be focud on one body area,such as cervical dystonia.p0010

Both the structure and validity and reliability of the F–M rating scale were first reported in 1985.The scale was subquently first ud in the context of a therapeutic trial with trihexyphenidyl for the treatment of torsion dystonia.

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The F–M rating scale is compod of two ctions:a movement scale bad on the neurological examination and a disability scale bad on the patient’s opinion of his disability in activities of daily l

iving.The movement scale is further divided in nine body regions:eyes,mouth,speech and swallowing,neck,right arm,left arm,trunk,right leg,and left leg.Individual scores are obtained for each body region;from 0to 8for the eyes,mouth,and neck,and from 0to 16for the other body parts.The individual scores are calculated for each body region

using a formula that takes a provoking factor,a verity factor and a weighting factor into account.The eyes,mouth,and neck are ‘down-weighted’becau when involved,the regions were not suggested to cau as much disability.The provoking factor is scored from 0to 4as following:0–No dystonia,1–Dystonia on particular action,2–Dystonia on many actions,3–Dystonia on action of a distant body part (overflow)or intermittently at rest,and 4–Dystonia at rest.For speech and swallowing,the provoking factor is slightly different,and is bad on frequency.The verity factors are scored similarly for all regions except speech and swallowing.Some site-specific criteria apply according to the specific abnormal movement or posture caud by the dystonia (e.g.,bending of the trunk with truncal dystonia,blinking or spasms of eye closure with blepharospasm).In general,the verity factors range from 0to 4,with 0–No dystonia,1–Slight dystonia,2–Mild dystonia,3–Moderate dystonia,and 4–Severe dystonia,with different ratings for speech and swallowing.Once individual scores for each body part are calculated,they are summed to obtain the movement scale score.The scale ranges from minimum of 0to maximum of 120.

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For the disability score,ven activities of daily living are rated according to the patient’s perception of his/her disability:speech,writing,feeding,eating,hygiene,dress-ing,and walking.The scores are from 0to 4(except for walking,from 0to 6),and scores are task specific.In general,scores are determined according to the following scale:0–Normal,1–Slight difficulty,2–Some difficulty,3–Marked difficulty,and 4–Severe difficulty,unable to perform the activity.The scale for walking is slightly different,ranging from 0to 6;with a score of 6assigned if the subject is wheelchair bound.Once the scores for all the individual activities of daily living are obtained,they are summed to obtain the total disability score,which ranges from 0to 30.

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Metrics of the Scale:Reliability and Validity

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The validity of the scale asss how well the scale reflects a gold standard rating.As clinical asssment of dystonia remains the de facto ‘gold standard,’the validity of the motor portion of the scale reflects how well the scores correlate with the clinical impression of dystonia

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verity.For example,when the dystonia is perceived as vere by an experienced neurologist,a valid scale would lead to a high score.The conver is true for a dystonia perceived as mild by the clinician.On the other hand,the reliability of the scale corresponds to how reproducible the score is,among different examiners (interrater reli-ability),but also from the same examiner at different times (intrarater reliability).

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The validity and reliability of the F–M rating scale were first evaluated by Burke and colleagues in 1985.The validity was evaluated by comparing the F–M score with the global clinical impression of verity and with the disability score.The reliability was assd by first,com-paring evaluations of the 10patients on two occasions by two examiners (intrarater validity)and cond,by exam-ining the correlation of the ten evaluations of the three examiners.The scale was shown to be both reasonably valid and reliable for patients with primary torsion dysto-nia.However,only a small number of patients were assd,and becau dystonia is so heterogeneous,the broader spectrum of dystonia was not tested.Further,the degree of agreement for individual body sites was not reported.

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Two large multicenter studies have since evaluated the F–M scale.Comella and colleagues evaluated the reli-ability of the scale using 20videotaped patients,and 25dystonia experts,and compared the scale to the UDRS (Unified Dystonia Rating Scale)and GDS (Global Dystonia Rating Scale).They concluded that all three scales were internally consistent,showed good to excel-lent interrater reliability (intraclass correlation coeffi-cient,0.71–0.78),but that the provoking factor in the F–M demonstrated less interrater agreement than the motor verity ratings.Further,they found that the GDS (which includes rating for proximal and distal limbs pa-rately,and does not include subject

ive speech and swal-lowing ratings,and does not include weighting factors)was easier to administer than the F–M.Krystkowiak and colleagues further demonstrated reliability in a prospec-tive asssment of the F–M scale ud to track verity and disability of primary generalized dystonia treated with deep brain stimulation.

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Applications of the Scale

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The F–M scale was first ud to asss the efficacy of trihexyphenidyl as a treatment for primary and condary dystonia.It is now primarily ud to asss the efficacy of deep brain stimulation surgery in both primary and cond-ary dystonia,usually in cas with generalized dystonia.

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Problems with the Scale

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As noted,the F–M rating scale has veral limitations.The major drawback in using the F–M scale is lack of ea in administration,which relates to parately determining provoking and verity factors.The GDS was developed as an alternative to the F–M,and has been shown to be at least as reliable and valid but simpler and easier to apply.The UDRS was developed to address the F–M scale’s limitations regarding the flexibility to report specific sites as the rated areas are smaller and more defined,and shows great promi.The F–M scale is also limited in its applicability for some dystonia plus syndromes and condary dystonias as it is focud on dystonia,and additional movement disorders,such as myoclonus and features of condary dystonia,such as that due to Wilson dia,or spasticity associated with other forms of c-ondary dystonia are not captured.In the situations,dia specific scales,such as the Wilson Dia Scale,may be more applicable.

See also:Basal Ganglia (00015);Animal Models for Dystonia (00095);Dystonia (00104);DYT 1(00109);DYT11,DYT15–Myoclonus-Dystonia (00111);Dyt12–Rapid Ont Dystonia Parkinsonism (00112);DYT2-Autosomal Recessive Generalized Dystonia (00114);Dyt4Autosomal Dominant Type Dystonia or Whispering Dysphonia (00116);DYT 5(00117);Hypnic Jerks (00126);Dystonia in Amish-Mennonite and Mennonite Families (00128);Generalized Primary Torsion Dystonia (00134);Wilsons Dia (00430).