Compare conditions

Put any two — or three — conditions side by side, adult or pediatric, to spot the look-alike differences fast, row by row.

Parkinsons Disease

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In one line

·The substantia nigra (a small dark spot deep in the brain that makes dopamine) loses its dopamine-making nerve cells, so the brain cannot send smooth movement signals anymore.

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Normal physiology

·The substantia nigra (a small dark cluster of cells deep in the midbrain) makes dopamine and ships it along a highway of nerves to the striatum (the brain's movement-control center). The striatum uses that dopamine to fine-tune every movement—starting it, stopping it, and keeping it smooth and quick.

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What goes wrong

·A sticky, misfolded protein called alpha-synuclein clumps together inside dopamine-making cells in the substantia nigra and kills them. Once 60 to 80 percent of the cells are dead, the striatum runs out of dopamine, and the brain can no longer send smooth movement signals.

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Hallmark signs

·Resting tremor (shaking when the limb is still)
·Bradykinesia (movements become slow and small)
·Rigidity (muscles feel stiff and resist when someone bends your arm or leg)
·Postural instability (trouble balancing, shuffling gait, tendency to fall backward)
·Masked face (reduced facial expression, less blinking)
·Micrographia (handwriting gets tiny and cramped)
·Soft, monotone voice (hypophonia)
·Loss of smell (hyposmia or anosmia, often years before motor symptoms)

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Red flags · escalate now

·Falls within the first year of symptoms (suggests a faster, broader brain disease rather than classic Parkinson's)
·Severe blood-pressure drops when standing, early bladder failure, or trouble swallowing within the first year (points to multiple system atrophy)
·Rapid progression with prominent dementia, hallucinations not caused by medication, or no response to levodopa (the main Parkinson's drug)
·Prominent downward-gaze palsy (can't look down) or backward falls early on (suggests progressive supranuclear palsy)
·Symptoms that begin symmetrically on both sides of the body at once (classic Parkinson's almost always starts on one side)

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Workup

·Clinical diagnosis using the Movement Disorder Society criteria
·Brain MRI without contrast
·DaTscan (ioflupane I-123 SPECT imaging of dopamine transporters)
·Levodopa challenge test (100/25 mg levodopa-carbidopa given once, exam repeated after 60 minutes)
·Autonomic function testing (tilt table, heart rate variability, thermoregulatory sweat test, bladder residual)
·Polysomnography (overnight sleep study) with video and EMG during REM sleep
·Serum ceruloplasmin and 24-hour urine copper (in patients under 50)
·Medication and toxin history review

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Treatment

·Levodopa-carbidopa, started at 100/25 mg three times daily and slowly increased every few days to find the lowest effective dose
·Dopamine agonists (pramipexole 0.125–1.5 mg three times daily, or ropinirole 0.25–8 mg three times daily) in patients under 65
·MAO-B inhibitor (rasagiline 1 mg daily or selegiline 5 mg twice daily)
·COMT inhibitor (entacapone 200 mg with each levodopa dose, or tolcapone 100–200 mg three times daily) added when wearing-off starts
·Physical therapy with LSVT BIG protocol, occupational therapy, and speech therapy with LSVT LOUD protocol
·SSRI or SNRI (sertraline, citalopram, venlafaxine) for depression; rivastigmine for dementia; pimavanserin 34 mg daily for hallucinations
·Deep brain stimulation (DBS) targeting the subthalamic nucleus or globus pallidus interna with implanted electrodes

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NCLEX trap

·Older antipsychotics block dopamine receptors (the spots on brain cells where dopamine lands and delivers its signal) and make Parkinson disease much worse — more stiffness, more tremor, more trouble walking. Use pimavanserin (blocks serotonin but not dopamine) or quetiapine (barely touches dopamine receptors) instead. These are safer for Parkinson disease.
·Never stop levodopa cold in Parkinson disease. Sudden withdrawal triggers a life-threatening crisis that looks like neuroleptic malignant syndrome: high fever (over 104°F), rigid muscles (like steel pipes), confused thinking, blood pressure swings, organ shutdown, and death. Always taper levodopa slowly over days to weeks.
·Parkinson disease is one-sided or very uneven (asymmetric) early on. If symptoms are equal on both sides from day one, think atypical parkinsonism like progressive supranuclear palsy, multiple system atrophy, or corticobasal degeneration. These do not respond well to levodopa.
·Acting out dreams (called REM behavior disorder) is a red flag for Parkinson disease. Alpha-synuclein (the sticky protein that clumps and kills brain cells in Parkinson) has already damaged cells in the pedunculopontine nucleus and other brainstem areas that normally keep muscles still during REM sleep. This can show up years before the tremor or stiffness appears.
·In Parkinson disease, constipation, depression, memory loss, and problems with blood pressure or bladder control are all parts of the same disease. Alpha-synuclein spreads through many brain areas (the gut, the limbic system for mood, the cortex for thinking, the autonomic centers for blood pressure and bladder) and damages them. These are not separate illnesses; they are all downstream effects of alpha-synuclein killing cells.
·Always start levodopa low and go slow in Parkinson disease. Slow titration (gradual increase over weeks) prevents nausea, dizziness, and dyskinesia (jerky, involuntary movements that look like dancing or squirming). The brain and body need time to adjust to the new supply of dopamine.

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