The Movement Disorder Society Task Force recently published a proposal for new diagnostic criteria for 3 Huntington disease categories, including manifest Huntington disease, presymptomatic Huntington disease, and prodromal Huntington disease. The full description of these categories was published in Movement Disorders Clinical Practice.
An informal consensus from the task force suggested that current motor diagnostic criteria of Huntington disease should consider adding nonmotor signs, including cognitive signs. Cognitive disorders tend to be more difficult to diagnose; however, members of the task force suggested using criteria from the Diagnostic and Statistical Manual, Fifth Edition (DSM-V), for major neurocognitive disorder or minor neurocognitive disorder in manifest Huntington disease. The National Institute of Neurological Disorders and Stroke Common Data Elements for Huntington disease, cognitive domain, was also highlighted as a useful resource.
The authors also proposed prodromal Huntington disease as a new diagnostic category. As executive dysfunction is a common cognitive change in the prodromal period of Huntington disease, the task force suggested “motor diagnostic confidence of 2 plus clear cognitive (although possibly subtle) cognitive changes” is sufficient for diagnosing prodromal Huntington disease. The treatment of motor or emotional features of prodromal Huntington disease may be important, as is counseling on family and social issues.
For the presymptomatic Huntington disease category, the task force suggested that “it is important to establish a category for individuals who have the CAG expansion but as of yet have no signs or symptoms related to [Huntington disease].” Relevant patients would display no cognitive changes or motor signs on exam, but may be candidates for future disease-modifying treatment to delay or prevent onset of symptoms.
A category for premanifest Huntington disease is also included in the task force proposal. This is defined as the period before manifest Huntington disease that includes both presymptomatic and prodromal periods.
Because Huntington disease is a clinical diagnosis, the authors wrote that the proposed diagnostic categories should be primarily based on the patient’s clinical status, rather than genetic or diagnostic testing.
The task force highlights that although the proposed criteria are the result of holistic considerations of a selective group of publications and expert opinion, they were based on an informal consensus process that lacks validation in terms of accuracy and usability in future studies.
“The currently proposed criteria are primarily designed for research because they use the research-based examination,” the task force noted. They add that “as clinical trials of disease-modifying therapy are advancing rapidly and early intervention may be most beneficial, we believe that clinical application should come soon, and that it is especially timely to include the prodromal [Huntington disease] diagnosis.”
Ross CA, Reilmann R, Cardoso F, et al. Movement disorder society task force viewpoint: Huntington’s disease diagnostic categories. Mov Disord Clin Pract. 2019;6(7):541-546