Neuroscience · Year 2 · from Neuroscience
Case 2: Huntington's Disease
Patient Presentation
Demographics: 42-year-old female, accountant
Chief Complaint: Involuntary movements and personality changes over 2 years
History of Present Illness: The patient was brought in by her husband who reports she has developed jerky, involuntary movements affecting her arms, legs, and face over the past two years. Initially, these were subtle fidgeting movements she seemed to incorporate into normal gestures, but they have become more pronounced and are now interfering with her work and daily activities. Her husband also notes significant personality changes: she has become irritable, apathetic, and has made several impulsive financial decisions that are uncharacteristic. She has been forgetting appointments and struggling with work tasks that were previously easy for her. The patient's father died at age 52 with similar symptoms and was diagnosed with a "movement disorder." Her paternal grandmother also had involuntary movements before her death.
Physical Examination:
- General: Alert, appears fidgety with nearly continuous involuntary movements
- Mental status: MoCA 22/30 with deficits in executive function and recall; poor insight into symptoms
- Cranial nerves: Intact, motor impersistence noted (difficulty maintaining tongue protrusion and eye closure)
- Motor:
- Choreiform movements: Random, flowing, dance-like movements involving face (grimacing, eyebrow raising), trunk, and all four limbs
- Movements incorporated into voluntary actions (parakinesia)
- Tone: Mildly reduced (hypotonic)
- Strength: 5/5 throughout
- Sensory: Intact
- Reflexes: 2+ throughout, plantar responses flexor
- Gait: Wide-based, lurching quality with incorporated choreiform movements
- Psychiatric: Flat affect with occasional inappropriate laughter
Workup:
- Brain MRI: Bilateral caudate atrophy with "box-car" appearance of frontal horns of lateral ventricles; mild generalized cortical atrophy
- Genetic testing: HTT gene analysis revealed 45 CAG repeats (normal < 36; disease-causing >= 40)
Diagnosis: Huntington's disease
Treatment:
- Tetrabenazine 12.5 mg twice daily initiated for chorea, with plan to titrate slowly
- Neuropsychiatric evaluation
- Genetic counseling for the patient and family members (50% risk to each child)
- Social work referral for long-term care planning
- Depression screening with consideration of antidepressant therapy
- Referral to Huntington's Disease Society of America support group
Clinical Pearl: Huntington's disease results from CAG trinucleotide repeat expansion in the huntingtin gene on chromosome 4. The triad of motor (chorea), cognitive (executive dysfunction progressing to dementia), and psychiatric (depression, irritability, psychosis) features is characteristic. Anticipation causes earlier onset and more severe disease in successive generations due to expansion of the CAG repeat during transmission. Genetic counseling is essential given the autosomal dominant inheritance and profound implications for family members.
Clinical Image
Image Description: MRI or CT demonstrating basal ganglia structures. In Parkinson's disease, routine MRI is typically normal but DaTscan shows reduced dopamine transporter uptake. In Huntington's disease, characteristic caudate atrophy produces enlarged frontal horns of the lateral ventricles ("box-car" ventricles).
Attribution: Image from Radiopaedia (https://radiopaedia.org/), Creative Commons Attribution-NonCommercial-ShareAlike 3.0 license.