Movement Disorders & Parkinson's Disease Overview

Movement Disorders Overview

• Movement disorders are a group of neurological conditions causing abnormal involuntary movements.
• Parkinson's disease (PD) is a chronic, progressive neurodegenerative disorder.
• PD is characterized by a loss of dopaminergic neurons in the substantia nigra pars compacta and locus coeruleus

Parkinson's Disease (PD)

• Named after James Parkinson, who published "An Essay on the Shaking Palsy" in 1817.
• PD is a chronic progressive neurodegenerative disease affecting movement.
• It's characterized by a loss of dopaminergic neurons in the substantia nigra.
• PD diagnosis requires a careful neurological examination, blood tests, an MRI scan, and PET/SPECT scans.

Pathophysiology of PD

• Significant loss of dopamine in the substantia nigra is a key factor.
• This leads to an imbalance between dopamine and acetylcholine levels in the basal ganglia.
• Various pathways including mitochondrial dysfunction/oxidative stress, impaired ubiquitin-proteasomal system, and aberrant protein accumulation contribute to PD development.
• The presence of Lewy bodies, which are eosinophilic cytoplasmic inclusions, is a hallmark of the disease.
• α-synuclein aggregation into Lewy bodies is critically involved.

Epidemiology of PD

• Incidence increases dramatically with age, with onset typically occurring in the 50-60+ age group.
• Overall incidence is reported as 15-25/100,000.
• 4-10% of individuals develop PD before reaching 40 years of age; this is referred to as young-onset PD.
• Juvenile-onset PD is defined by symptom presentation prior to 20 years old.
• PD is slightly more common in males.
• Environmental factors such as exposure to pesticides, toxins, and well water, and possibly a family history, may contribute as risk factors.

Clinical Picture of PD

• Typical PD presents with an insidious onset and a progressive course, starting unilaterally then becoming bilateral.
• Key symptoms include bradykinesia, resting tremors, rigidity, and postural instability.
• Other features include difficulty with initiating and performing voluntary movements. Loss of postural reflexes and emotional expression may occur. Problems with gait, including shuffling and short steps are also common.

Non-Motor Impairments in PD

• PD often involves non-motor impairments, including:
• Autonomic dysfunction (e.g., orthostatic hypotension, sweating dysfunction, sphincter dysfunction, and erectile dysfunction)
• Cognitive and neurobehavioral abnormalities (e.g., dementia, depression, anxiety, hallucinations)
• Sleep disorders (e.g., REM behavior disorder)
• Sensory abnormalities (e.g., olfactory dysfunction, paresthesia, akathisia)

Diagnostic Testing for PD

• Careful neurological examination is crucial.
• Blood tests can exclude other causes of tremors.
• MRI brain scans identify any secondary causes.
• PET and SPECT scans measure dopamine levels in the striatum differentiating PD from similar conditions.

Differential Diagnosis of Parkinsonism

• Parkinsonian tremors: Distinguishing Essential Tremors, Psychogenic Tremors, and other conditions
• Secondary parkinsonism: Differentiating vascular parkinsonism (risk factors, predominant rigidity, pyramidal signs, predominantly affects lower limbs), Post-encephalitic parkinsonism (any age, presence of pyramidal signs, mental changes, other neurological deficits) , Post-traumatic parkinsonism (repetitive head trauma), Drug-induced parkinsonism,Wilson disease, or Hydrocephalic parkinsonism.

Management of PD

• Drugs: L-dopa and dopamine agonists, MAO inhibitors, and COMT inhibitors
• Gene therapy: Potential therapies using viral vectors.
• Surgical Interventions: Stereotactic ablative surgery (thalamotomy, pallidotomy, subthalamotomy or deep brain stimulation (DBS)).
• Physiotherapy is a supplemental treatment to manage movement, balance, muscle stiffness, and discomfort.

Goals of Medical PD Treatment

• There's currently no cure for Parkinson's disease.
• Treatment aims to alleviate symptoms rather than stopping the disease's progression.
• The aim is to provide symptomatic relief.
• Treatment's goal is to temporarily restore function and enhance quality of life.
• Individual responses to medications vary. Specific treatments for specific cases can be discussed based on individual needs.

Movement Disorders Classification

• Akinetic-rigidity syndrome: conditions associated with impaired movement, rigidity. Parkinson's, post-encephalitic parkinsonism, etc.
• Hyperkinetic-hypotonic syndrome: conditions with abnormal involuntary movements. Chorea, Hemiballism, Athetosis, Dystonia, Myoclonus, Tics, etc.

Specific Movement Disorders

• Chorea: Irregular, sudden, brief, and unexpected movements. Common causes include medications (tardive dyskinesia), Huntington's Disease, Hemiballism, post-infectious (Streptococcal), and pregnancy, etc.
• Sydenham's chorea: particular type of chorea linked with rheumatic fever. Primarily affects children, with onset appearing months after the infection.
• Hemiballismus: Violent and sudden, large-amplitude, unilateral movements typically due to a stroke in the subthalamic nucleus.
• Athetosis: Slow, continuous, writhing movements primarily affecting the extremities, often associated with damage to the putamen.
• Dystonia: Sustained, involuntary muscle contractions leading to abnormal postures and movements potentially occurring in generalized or focal forms (Blepharospasm (eyes), Oromandibular dystonia (face and mouth), Spasmodic dysphonia (voice), Writer's cramp).
• Myoclonus: Sudden, shock-like muscle contractions, either focal, multifocal or generalized; may arise from various conditions ranging from epileptic or non-epileptic.
• Tics: Intermittent, repetitive, stereotyped movements or sounds. Mostly in children, resolves spontaneously, however, medical intervention may be required for severe or socially impairing cases.