Parkinsonism

Parkinson’s Disease

•    Core features: bradykinesia + resting tremor + rigidity + postural instability.

•    Other features: micrographia, hypophonia, shuffling gait, reduced arm swing, facial masking (hypomimia).

•    Pathology: loss of dopaminergic neurons in substantia nigra pars compacta; Lewy bodies (α-synuclein).

•    Treatment:

o    Levodopa (+ dopa decarboxylase inhibitor): most effective for 

                                bradykinesia/rigidity; long-term risk of dyskinesias, motor fluctuations.

o    Dopamine agonists (e.g., ropinirole, pramipexole): risk of impulse control disorders.

o    MAO-B inhibitors (e.g., selegiline): mild symptomatic benefit.

Atypical Parkinsonism (Parkinson-plus syndromes)

•    Multiple System Atrophy (MSA):

o    Early autonomic dysfunction (e.g., postural hypotension, erectile dysfunction).

o    Cerebellar or pyramidal signs.

•    Progressive Supranuclear Palsy (PSP):

o    Early postural instability and falls.

o    Vertical gaze palsy (esp. downgaze).

•    Corticobasal degeneration:

o    Asymmetric rigidity, apraxia, "alien limb" phenomenon.

Tremor

Essential Tremor

•    Type: action/postural tremor (e.g., holding cup).

•    Improves with alcohol, worsens with stress.

•    Rx: propranolol (first-line), primidone.

Parkinsonian Tremor

•    Type: resting tremor, "pill-rolling."

•    Improves with voluntary movement.

Chorea

Huntington’s Disease

•    Genetics: autosomal dominant, CAG trinucleotide repeat on chromosome 4.

•    Clinical triad: chorea, psychiatric symptoms (depression, irritability), cognitive decline.

•    Anticipation: earlier onset in successive generations.

•    MRI: caudate nucleus atrophy ("boxcar ventricles").

Sydenham’s Chorea

•    Post-streptococcal (Group A beta-haemolytic Strep)

•    Associated with rheumatic fever (Jones criteria).

•    Self-limiting, supportive treatment ± penicillin prophylaxis.

Dystonia and Myoclonus

•    Dystonia: sustained or intermittent muscle contractions → abnormal postures or repetitive movements.

o    Causes: idiopathic, medication-induced (dopamine blockers), Wilson’s disease.

•    Myoclonus: sudden, brief, shock-like involuntary movements.

o    Causes: metabolic (e.g., uraemia), post-hypoxic, epilepsy-related, medications.

Wilson’s Disease

•    Inheritance: autosomal recessive (ATP7B gene mutation).

•    Pathophysiology: defective copper excretion → copper accumulation in liver, brain, cornea.

•    Clinical:

o    Hepatic: chronic liver disease, acute hepatitis, fulminant liver failure.

o    Neuropsychiatric: dystonia, dysarthria, tremor, behavioural changes.

o    Kayser–Fleischer rings (copper deposition in Descemet’s membrane).

•    Investigations: ↓ serum ceruloplasmin, ↑ urinary copper excretion, hepatic copper quantification.

•    Treatment: chelation (penicillamine), zinc (blocks absorption), liver transplant in fulminant cases.

Extra Revision Pearls

•    Essential tremor clue → improves with alcohol

•    Early falls clue → PSP (vs Parkinson’s)

•    Vertical gaze palsy clue → PSP

•    Chorea + behavioural symptoms clue → Huntington’s

•    Young liver disease + neuropsychiatric clue → Wilson’s

•    Pill-rolling clue → Parkinson’s