Movement disorders overview

Cerebellar Disease

• Symptoms: Impaired coordination, bradykinesia, involuntary movements (hyperkinesias), tremor, chorea/dystonia, nystagmus, impaired gait.
• Extrapyramidal Tracts: Pathways involved in reflexes (e.g., head/trunk movement in response to noise), locomotion, complex movements, and postural control. Modulated by the cerebellum, basal ganglia, vestibular nuclei, and parts of the cerebral cortex.
• Mechanics: The premotor cortex initiates movement. Corticospinal and corticobulbar tracts control gross voluntary muscle movement. Basal ganglia facilitate wanted motions and suppress unwanted ones. The cerebellum uses feedforward (anticipatory) and feedback (corrective) mechanisms during movement. Sensory system (proprioception) and thalamus relay information.
• Causes: Vascular (posterior circulation issues), infectious (abscesses, viral cerebellitis, Creutzfeldt-Jakob disease), neurological (demyelination), neoplastic (tumors), degenerative (spinocerebellar ataxias, multi-system atrophy), intoxication (alcohol, phenytoin), metabolic (myxoedema, hypoglycaemia, hypoxia, vitamin B1 deficiency).
• Symptoms (Cerebellar Dysfunction): Ataxia, decomposition of complex movements, impaired balance (possible acute loss of extensor muscle control).
• Signs (Cerebellar Dysfunction): Pendular reflexes (hypotonia), dysdiadochokinesia (impaired rapid alternating movements), action/intention tremor, rebound phenomenon, nystagmus.

Parkinson's Disease

• Aetiology: Unknown. Possible factors include gene mutations, environmental factors (smoking, herbicides), and meperidine analogue toxicity.
• Pathology: Loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc). Remaining cells contain Lewy bodies. The disease progresses to affect other brain regions.
• Prevalence: Approximately 190 per 100,000 (1% of people >60).
• Sex Ratio: 3:2 (male to female).
• Onset Age: Typically >50 years old.
• Familial cases: 5% of Parkinson's cases are familial.
• Risk Factors: Genetics, environmental factors (rural living, chemical exposures, infections), age (higher risk with increasing age), male sex more common than female sex.
• Symptoms (Early): Subtle dexterity decline, tremor (pill-rolling), reduced arm swing on affected side, soft voice, reduced facial expression (hypomimia), reduced sense of smell, sleep disturbances, autonomic issues (sweating, constipation), generalized lassitude, weakness, and malaise.
• Symptoms (Later): Rigidity (cogwheel, lead pipe), bradykinesia (difficulty initiating movement affecting facial expression, speech, swallowing, and gait), shuffling gait, flexed posture, possible depression, dementia.

Huntington's Disease

• Description: Rare autosomal dominant disorder with progressive neuronal loss in the striatum, frontal, and parietal cortex. Associated with GABA, acetylcholine, and dopamine pathways.
• Onset: Adulthood (30-50 years old).
• Symptoms: Chorea (irregular, jerky involuntary movements) which may be accompanied by or replaced by dystonia and parkinsonism symptoms. Early irritability, loss of interest, cognitive decline, memory issues, speech problems, behavioral disturbances (affective illness, depression, bipolar).
• Prognosis: Death typically 15-20 years after onset due to complications such as aspiration pneumonia or suicide.

Vertebrobasilar Arterial Insufficiency (VBAI)

• Causes: Atheroma (plaque buildup) or dissection (tearing) of the artery.
• Symptoms (5 D's, 3 N's): Dizziness, dysphagia (difficulty swallowing), dysarthria (speech difficulty), diplopia (double vision), drop attacks; nausea, numbness, nystagmus; ataxia.

Posterior Inferior Cerebellar Artery (PICA) Occlusion

• Description: Common type of brainstem stroke, also called lateral medullary infarct or Wallenberg's syndrome.
• Symptoms: Cerebellar signs (vertigo, ipsilateral hemiataxia, dysarthria), ipsilateral facial pain (CN5), contralateral loss of pain and temperature sensation in the extremities (crossed syndrome), ptosis (drooping eyelid), meiosis (constricted pupil), interruption of descending sympathetic fibers.

Dandy-Walker Syndrome

• Description: Rare congenital malformation causing dilation of ventricles (especially the fourth ventricle), underdeveloped or separated cerebellar hemispheres, and enlarged posterior fossa.
• Symptoms: Delayed motor development, progressive enlargement of the skull (or back of head), increased intracranial pressure (ICP) symptoms (irritability, vomiting), signs of cerebellar dysfunction, cranial nerve dysfunction.
• Treatment: Shunt for hydrocephalus, treatment of associated symptoms.

Tremor

• Description: Rhythmic, regular oscillation of a body part. Common locations include hands, jaw, tongue, and head.
• Types: Resting, postural, intention, end-point.
• Essential Tremor: Most common. Familial link, slowly progressive postural or kinetic tremor of both upper limbs. Can also affect the head, voice, jaw, lips, and face. Starts in one extremity, progresses to both. Can be intermittent or emotionally triggered, variable amplitude. Improves with relaxation and sleep. Little impact on activities of daily living (ADLs).
• Abnormal Tremor: Parkinsonian tremor (rest tremor, "pill-rolling" motions), cerebellar tremor (intention tremor), postural tremor, end-point tremor, drug-induced/metabolic tremor (e.g., adrenaline, alcohol withdrawal, hyperthyroidism), psychogenic tremor.

Arnold-Chiari Malformation

• Chiari II: Cerebellum and brainstem impacted, always with myelomeningocele (spina bifida). Common symptoms include hydrocephalus at birth and syringomyelia. May present with occipital pain, weakness.
• Types III/IV: Rare, profound neurological deficits.
• Treatment: Hydrocephalus shunt, decompression surgery (if asymptomatic, surgery not needed).