# Clinical Cases: Basal Ganglia ## Case 1: Parkinson's Disease ### Patient Presentation **Demographics:** 68-year-old male, retired engineer **Chief Complaint:** Progressive tremor of right hand and slowness of movement over 18 months **History of Present Illness:** The patient first noticed a fine tremor in his right hand approximately 18 months ago, initially appearing only when he was at rest watching television. Over the past year, the tremor has become more prominent and he has developed difficulty buttoning his shirt and using utensils. His wife reports that he has become noticeably slower in all his movements and his handwriting has become smaller and more difficult to read. He has also noticed stiffness in his right arm and leg, and his posture has become more stooped. He denies any cognitive changes, hallucinations, or significant mood disturbance. No history of head trauma, antipsychotic use, or exposure to toxins. Family history is negative for movement disorders. **Physical Examination:** - General: Alert, oriented, mildly hypomimic (reduced facial expression) - Mental status: MMSE 29/30, no evidence of dementia - Cranial nerves: Reduced blink rate, hypophonic speech, otherwise intact - Motor: - Resting tremor of right hand (4-5 Hz, pill-rolling type), suppressed with movement - Mild resting tremor of right foot - Cogwheel rigidity in right upper and lower extremities - Bradykinesia demonstrated by finger tapping with progressive decrease in amplitude - Strength 5/5 throughout - Sensory: Intact to all modalities - Reflexes: 2+ throughout, plantar responses flexor bilaterally - Gait: Reduced right arm swing, shortened stride length, mild shuffling, no festination - Postural reflexes: Mildly impaired on pull test **Workup:** - Brain MRI: No evidence of vascular parkinsonism, normal pressure hydrocephalus, or structural lesion. Mild age-appropriate atrophy. - DaTscan (dopamine transporter imaging): Reduced uptake in left putamen consistent with presynaptic dopaminergic deficit **Diagnosis:** Idiopathic Parkinson's disease, Hoehn and Yahr Stage 2 **Treatment:** - Started carbidopa-levodopa 25/100 mg three times daily with meals - Physical therapy referral for gait training and balance exercises - Occupational therapy for fine motor skills - Follow-up in 6 weeks to assess response and titrate medication **Clinical Pearl:** The cardinal motor features of Parkinson's disease can be remembered by the mnemonic TRAP: Tremor (at rest), Rigidity (cogwheel type), Akinesia/Bradykinesia, and Postural instability. Asymmetric onset is characteristic, and excellent response to levodopa supports the diagnosis. Red flags suggesting Parkinson-plus syndromes include early falls, poor levodopa response, early dementia, prominent autonomic failure, and symmetric presentation. --- ## 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 ![Basal ganglia imaging](case_01_image.jpg) **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.