Movement Disorders Viva

Long Case Viva Defence

Candidate's opening statement (model answer)

"Mr Robert Hayes is a 73-year-old retired electrician with Parkinson's disease diagnosed 11 years ago, presenting with worsening function from motor fluctuations, dyskinesia, hallucinations and falls. ^[1]

His past history includes:

• Idiopathic Parkinson's disease, diagnosed age 62, initially tremor-dominant and levodopa-responsive, now with wearing off and dyskinesia
• Hypertension, well-controlled on ramipril
• No prior psychiatric history, no cognitive impairment until recently
• Independent in activities of daily living until 12 months ago, now requiring assistance with dressing ^[1]

His current medications are:

• Levodopa/carbidopa 100/25 six times daily
• Entacapone 200 mg with each levodopa dose
• Ropinirole prolonged-release 8 mg daily
• Rasagiline 1 mg daily
• Ramipril 5 mg daily ^[1]

His main problems are:

1. Wearing off — each levodopa dose now lasts only 2 hours, with disabling off periods
2. Peak-dose dyskinesia — choreiform movements of trunk and arms 1 hour after each dose, more disabling than the off periods
3. Visual hallucinations — formed, detailed, people and animals, with retained insight, in the evenings
4. Freezing of gait with falls — three falls in the last month, twice on turning
5. Cognitive decline — MoCA 24/30, with frontal-executive features
6. Polypharmacy — four dopaminergic agents from three drug classes, increasing hallucination risk ^[1]

My integrated plan is to restructure his dopaminergic therapy around the dominant complaint of dyskinesia by reducing individual levodopa dose size and increasing frequency, add amantadine for the dyskinesia, wean the dopamine agonist to reduce the hallucination burden, add a cholinesterase inhibitor for cognition and psychosis, institute cueing strategies and physiotherapy for the freezing of gait, and initiate multidisciplinary review and advance care planning." ^[1]

Examiner probing questions and model answers

Q1: "He is on ropinirole and has developed hallucinations. Walk me through your pharmacological approach to the hallucinations." ^[1]

"My approach follows a stepwise framework. First, I exclude delirium — I would check for infection, particularly urinary tract and respiratory, check electrolytes including sodium and calcium, and review all his medications for anticholinergic load. Many 'PD hallucinations' seen in clinic are unmasked delirium. Once delirium is excluded, I address the dopaminergic therapy. The principle is to reduce the drugs with the highest neuropsychiatric burden first. The dopamine agonist ropinirole carries the highest risk of hallucinations, so I would wean and stop it first, transferring the dopaminergic load to levodopa. I would wean slowly over weeks to avoid the dopamine agonist withdrawal syndrome — drug-craving, depression, anxiety and pain that can mimic addiction withdrawal. I would also consider stopping the rasagiline if hallucinations persist. If these measures are insufficient, I would add a cholinesterase inhibitor — rivastigmine, which is licensed for PD dementia and improves both cognitive function and psychotic features, particularly in patients with co-existing cognitive impairment as he has. If an antipsychotic is genuinely unavoidable, the only evidence-based options are pimavanserin — a selective 5-HT2A inverse agonist, FDA-approved for PD psychosis but unavailable here in Australia — or low-dose quetiapine 12.5 to 25 mg at night, off-label, with caution. I must explicitly avoid haloperidol, chlorpromazine, risperidone and olanzapine, which cause catastrophic worsening of parkinsonism. I would counsel the family about the residual risk of quetiapine and document the discussion." ^[1]

Q2: "What is the role of dopamine agonist withdrawal syndrome, and how do you avoid it?" ^[1]

"Dopamine agonist withdrawal syndrome is a recognised complication of rapid agonist discontinuation, particularly with non-ergot agonists like pramipexole and ropinirole. It presents with drug-craving, anxiety, panic, depression, diffuse pain, diaphoresis and orthostatic hypotension, and can persist for weeks to months. It resembles — and may share mechanisms with — stimulant addiction withdrawal. To avoid it, I wean agonists slowly, reducing the dose by no more than 10 to 20 percent per week, and I transfer the dopaminergic load to levodopa in parallel to maintain total dopaminergic stimulation. I warn the patient and family about the syndrome in advance, monitor closely during the taper, and pause or reverse the taper if severe symptoms emerge. In patients who develop refractory withdrawal, a temporary increase in levodopa or a switch to a different agonist formulation may be required." ^[1]

Q3: "He has fallen three times this month. How do you assess and manage his falls?" ^[1]

"Falls in advanced Parkinson's disease are multifactorial and I approach them systematically. The contributors in this patient are: freezing of gait (which he describes as feet glued to the floor on turning, a levodopa-resistant axial symptom), possible orthostatic hypotension (he is on ramipril and four dopaminergic agents, both of which lower blood pressure), cognitive impairment (which reduces dual-tasking and attentional reserve for gait), and deconditioning. My assessment starts with a lying and standing blood pressure — looking for a drop of 20 systolic or 10 diastolic within 3 minutes of standing — a falls-focused history (circumstances, footwear, home hazards, time of day relative to medication), a cognitive assessment, a vision check, and a structured gait observation including the pull test. Management is multimodal: first, optimise the on-state to reduce off-period freezing; second, reduce causative medications — I would stop the ramipril if he is hypotensive and accept a higher blood pressure target; third, refer to a PD-specialist physiotherapist for cueing strategies — visual lines on the floor, a laser-cane, marching to a metronome set at his preferred cadence — and a PD-specific exercise programme; fourth, an occupational therapy home assessment for grab rails, removal of rugs, lighting; fifth, consider a walker, though I would be cautious as freezing can paradoxically worsen with a frame. I would screen his vitamin D and treat deficiency, and I would discuss a personal alarm and falls-prevention education with the patient and wife." ^[1]

Q4: "His wife asks whether deep brain stimulation would help him. How do you respond?" ^[1]

"I would counsel the family carefully. Deep brain stimulation is highly effective for the motor fluctuations and dyskinesia of advanced Parkinson's disease — the EARLYSTIM trial (PMID 23406026) showed significant quality-of-life benefit even in patients with early motor complications. However, three features of this patient make him a less suitable candidate. First, his cognitive decline — a MoCA of 24/30 is at the threshold, and significant dementia is a contraindication because DBS can worsen cognition, particularly verbal fluency and frontal-executive function. Second, his active visual hallucinations indicate neuropsychiatric vulnerability — STN-DBS in particular can worsen mood, apathy and impulsivity. Third, his freezing of gait is largely levodopa-resistant, and DBS does not help — and may worsen — axial symptoms like gait freezing, speech and postural instability that reflect non-dopaminergic disease progression. If a DBS referral were to be considered, I would insist on a formal neuropsychological assessment, a psychiatric review, and a multidisciplinary DBS team assessment. If he were to proceed, GPi-DBS would be preferred over STN-DBS given the better neuropsychiatric profile (Follett, PMID 20519680). I would be honest with the family that, on current assessment, device-aided therapy with levodopa-carbidopa intestinal gel or apomorphine infusion may be more appropriate than DBS given his cognitive and psychiatric profile, and that the priority for now is the medical restructuring I have outlined." ^[1]

Q5: "Why does he have visual hallucinations, and what does it tell you about his disease trajectory?" ^[1]

"Visual hallucinations in Parkinson's disease reflect a combination of factors: the cumulative dose and class of dopaminergic therapy, particularly dopamine agonists which stimulate mesolimbic D3 receptors; disease progression with alpha-synuclein pathology spreading from the brainstem into the limbic system and cortex (Braak stages 4 to 6); dysfunction of the visual association pathways and retina; REM sleep intrusion; and emerging cognitive impairment. The hallucinations are a marker of advanced disease and, importantly, they predict the development of dementia — patients with PD psychosis develop dementia earlier and more often than those without. They also signal a need to reassess the prognosis with the family, to simplify the medication regimen, and to consider advance care planning. The trajectory is now one of a patient transitioning from a predominantly motor disease to a multisystem neurodegenerative disease dominated by cognitive, psychiatric and axial motor features that are less responsive to dopaminergic therapy. This is the point at which the goals of care shift from motor optimisation to quality of life, cognition, falls prevention, and dignity." ^[1]