# 30 - Motor symptoms

# Motor symptoms

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The Maudsley® Prescribing Guidelines in Psychiatry
CHAPTER 10
Huntington’s disease
Huntington’s disease (HD) is a genetic neurodegenerative disease with an estimated 
prevalence of 4.88 individuals per 100,000 worldwide, and a higher incidence in Europe 
and North America.1 The mutant Huntington protein causes neuronal dysfunction and 
death through several mechanisms, resulting in a triad of motor, cognitive and neuropsychiatric symptoms.2 There are currently no disease-­modifying treatments3,4 so 
symptomatic therapies are used to improve quality of life (Box 10.3).
There are few controlled studies to guide practice in this area,3 although some direction can be drawn from published expert opinion and clinical experience. A summary 
of the available literature is given in this section. Readers are directed to the reports 
cited for details of dosage regimens and further information about tolerability. Clinicians 
who treat patients with HD are encouraged to publish reports of both positive and 
negative outcomes to increase the primary literature base.
Motor symptoms
Motor disturbances follow a biphasic course  – an initial hyperkinetic phase with 
prominent chorea which tends to plateau over time, and a later hypokinetic phase 
characterised by bradykinesia, dystonia, balance and gait disturbance.7 With regard 
to chorea, the goal of treatment is not to obliterate movements but to reduce their 
severity to achieve better tolerability.5 Treatment pathways are available to guide management.8 First-­line treatments include tetrabenazine (licensed) or SGAs (unlicensed) 
(Table 10.9).8 Monotherapy is preferred to prevent an increased risk of adverse effects 
and complicating the management of non-­motor symptoms.8
Box 10.3  General principles of pharmacological symptom management in Huntington’s disease5,6
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■Tailor management to the needs of the individual patient (treatment is typically initiated when 
symptoms become bothersome, interfering or socially stigmatising)
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■Check whether existing medications are causing or exacerbating symptoms before commencing 
new treatments
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■Prioritise treatment to target the most troublesome symptoms first, with consideration of 
comorbid features
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■Balance therapeutic benefit with the potential for adverse effects
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■Start with a low dose and titrate according to tolerability and response (patients are relatively 
more sensitive to cognitive and motor adverse effects which may also be difficult to distinguish 
from disease progression)
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■Regularly follow up with patients to address changes in treatment (because symptomology 
evolves with disease progression)