Huntington's Disease Case Study
Introduction
What is Huntington's Disease?
Huntington disease (HD) is an incurable, inherited disorder that occurs from gene mutation and results in the progressive degeneration of nerve cells in the brain[1].The basal ganglia is the primary location of degeneration, specifically the striatum located within it. The primary role of the basal ganglia is to coordinate movement so that it is smooth[2]. When the striatum degenerates, there is a decreased ability to inhibit unwanted movement[3]. This leads to an excessive amount of involuntary movement, known as chorea. HD affects the ability of individuals to move, think, and behave. HD typically first appears at the age of 30 to 40, however symptoms may present at any point in life[1]. HD that occurs before the age of 20 is called juvenile Huntington’s disease[1].
Pathophysiology[4]
HD has been found to occur from the mutation of the Huntington gene. The Huntington gene contains a repetition of the CAG trinucleotide protein that everyone is born with and is typically repeated anywhere between 10-35 times. The exact function of this gene is unknown, however it is believed to play a part in neural development. In HD, the mutated Huntington gene causes an increase in the number of repeats of the CAG trinucleotide, with more repetitions leading to a greater risk for the disease. It has been found that individuals with HD have the CAG trinucleotide repeat over 36 times, and in severe cases can be seen repeated over 120 times. This elongation of the protein is then fragmented into smaller sections, which accumulate on neurons within the brain and disrupt function. These neurons eventually die and the resulting neurodegeneration is associated with many of the symptoms commonly seen in Huntington’s.
Presentation
HD has been found to be heavily influenced by genetics. Everyone has the two copies of the Huntington gene, however those who have a mutation to at least one of these copies have a greater chance of experiencing the HD symptoms[5]. The inheritance of HD is autosomal dominant, which means that each child of a parent with HD has a 50% chance of inheriting the mutated copy, meaning that they have a 50% chance of inheriting the disease[6].
Signs & Symptoms[4]
Movement - chorea, dystonia, impaired gait/posture/balance, speech/swallowing, eye movement
Cognitive - difficulty organizing tasks, lack of impulse control, lack of awareness of their behaviours, troubles finding words, learning new information
Behavioural - depressive symptoms such as sadness, apathy, social withdrawal, insomnia, fatigue
Purpose of Discussing HD in a Case Study Format
The physiotherapy management of Huntington’s Disease is highly variable and highly dependent on the symptoms. This fictional case gives an opportunity for both physiotherapists and physiotherapy students to discuss and reflect about the route of assessment taken in order to prepare for clinical cases that may be observed. The discussions surrounding a simulated case allow for a significant learning opportunity for all involved, and overall an improvement in the approach to assessing and managing a case such as Huntington’s Disease.
Client Characteristics
Examination Findings
Subjective
History of Present Illness (HPI)
Past Medical History (PMHx)
Family History
Medications
Social History (SHx)
Health Habits (HH)
Current Functional Status (FnSt)
Functional History (FnHx)
Objective
Observation
Vital Signs
AROM & PROM
Strength
Neurological Scan
Balance
Ambulation
Cognitive Functioning
Outcome Measures
Berg Balance Scale (BBS)
Timed Up and Go (TUG) Test
Unified Huntington's Disease Rating Scale (UHDRS)
Montreal Cognitive Assessment (MoCA)
Short Form 36 (SF-36)
Clinical Impression
Problem List
Diagnosis
Interventions
Patient Centered Goals
Intervention Approaches & Techniques
Interdisciplinary Care Team Management
Physiotherapy
Occupational Therapy
Social Worker
Psychologist
Speech Language Pathologist
Physician
Outcome Reassessment - 6 Months Post-Referral
Berg Balance Scale (BBS)
Timed Up and Go (TUG) Test
Referrals
Discharge Planning
Discussion
Case Summary
Broader Implications
Self-Study Questions
References
- ↑ 1.0 1.1 1.2 Folstein SE. Huntington's Disease: A Disorder of Families. The Johns Hopkins University Press. 1989
- ↑ Reiner A, Dragatsis I, Dietrich P. Genetics and neuropathology of Huntington's disease. Int Rev Neurobiol. 2011;98:325-72. Doi 10.1016/B978-0-12-381328-2.00014-6.
- ↑ Waldvogel HJ, Kim EH, Tippett LJ, Vonsattel JP, Faull RL. The Neuropathology of Huntington's Disease. Curr Top Behav Neurosci. 2015;22:33-80. doi: 10.1007/7854_2014_354.
- ↑ 4.0 4.1 Roos RA. Huntington's disease: a clinical review. Orphanet J Rare Dis. 2010 Dec 20;5:40. doi: 10.1186/1750-1172-5-40
- ↑ Myers RH. Huntington's disease genetics. NeuroRx. 2004 Apr;1(2):255-62. doi: 10.1602/neurorx.1.2.255
- ↑ Conneally PM. Huntington disease: genetics and epidemiology. Am J Hum Genet. 1984 May; 36(3): 506-26. Doi: https://doi.org/10.1016/0888-7543(89)90062-1
