Atypical Parkinsonism and Clinical Features

Introduction

  • Speaker: Hugh Morris, neurology consultant with a specialization in atypical parkinsonism.

  • Overview of topics to cover:
      - Clinical features of atypical parkinsonian syndromes.
      - Brain systems related to atypical features in these conditions.
      - Physiological and neuroanatomical understanding of key conditions.

Atypical Parkinsonian Syndromes

Definition

  • Atypical parkinsonian syndromes, also known as Parkinson’s plus conditions, differ from classic Parkinson's disease.

  • They include conditions that are usually more aggressive and have a higher rate of progression.

Clinical Features to be Discussed

  • Gaze palsy (specifically supranuclear gaze palsies).

  • Apraxia (difficulty with skilled movements).

  • Bradykinesia (slowness in movement).

  • Gait disorders (abnormal walking patterns).

Progressive Supranuclear Palsy (PSP)

Overview

  • PSP is the most common atypical parkinsonian syndrome and a pure tauopathy characterized by tau protein deposition in the brain.

  • Clinical implications include rapid progression with significant loss of speech, swallowing, and walking ability, typically resulting in death within 6-8 years post-onset.

Diagnostic Criteria

  • Developed by the Luthor Society approximately 7 years prior.

  • Four clinical domains for diagnosis:
      - Ocular motor dysfunction (supranuclear palsy).
      - Postural instability (leading to frequent falls).
      - Akinesia (slowed movements).
      - Cognitive dysfunction (often frontal cognitive issues).

Common Features

  • Patients often present with visual symptoms that are initially mistaken for optical issues rather than eye movement control problems.

  • Characteristic symptoms:
      - Repeated falls (postural instability).
      - Signs of other Parkinsonisms (variable types of rigidity, tremor).
      - Cognitive dysfunction characterized by disinhibition and apathy.
      - Eye movement abnormalities, including square wave jerks and limited up and down movements.

Phenotypes of PSP

  1. PSP Richardson Syndrome (PSPRS): Classic form featuring ocular motor dysfunction and postural instability.

  2. PSP Parkinsonism: Presents more like typical Parkinson's but with unique characteristics.

  3. PSP with progressive gait freezing: Difficulty initiating walking, frequent freezing episodes.

Consequence of Misdiagnosis

  • Many patients initially diagnosed with Parkinson's disease actually have atypical parkinsonism, resulting in a delay in proper diagnosis and treatment.

Corticobasal Syndrome (CBS)

Overview

  • A tauopathy involving deposition of tau in the brain, particularly affecting the cortex and basal ganglia.

  • Primarily characterized by asymmetric symptoms where one side is more affected than the other.

Clinical Features

  • Symptoms include rigidity, dystonia, myoclonus, and particularly apraxia.

  • Apraxia: Difficulty executing learned skilled movements despite normal power and sensation.

  • Additional symptoms: alien limb phenomenon (affected limb moves involuntarily when eyes are closed).
        - This occurs due to loss of proprioceptive feedback from the parietal lobe.

Clinical Investigation

  • Testing for apraxia involves imitation of gestures; patients often show inability to copy simple movements.

  • Patients may have difficulty recognizing numbers traced on their hands, indicating loss of cortical sensation.

Differential Diagnosis

  • Similar symptoms can arise from other causes such as tumors, strokes, or Alzheimer’s disease affecting similar brain areas.

  • Biomarkers help exclude conditions like Alzheimer’s while diagnosing tau-related disorders like CBS.

Eye Movement Disorders

Eye Movement Systems

  • Eye movements can be classified into:
      - Saccadic eye movements: Rapid from point to point.
      - Smooth pursuit eye movements: Following a moving target.

Frontal Eye Fields and Brainstem Nuclei

  • Frontal eye fields initiate eye movements; communication with midbrain nuclei (third and fourth cranial nerve nuclei) control eye movement execution.

  • Supranuclear gaze palsy indicates issues above nuclei level.

Clinical Assessment of Eye Movements

  • Oculomotor apraxia: Patients may use head movements to initiate eye movement.

  • Videos demonstrate patients with both vertical and horizontal gaze difficulties.

Apraxia in Eye Movements

  • Patients struggle to initiate eye movements upon command but can respond reflexively to visual stimuli (demonstrated via videos).

  • Identification of specific midbrain lesions helps differentiate types of gaze palsy.

Bradykinesia

Comparison of Bradykinesia in Parkinson's Disease and PSP

  • Typical Parkinson's disease: noticeable slowness and decrement (progressively smaller movements).

  • PSP patients exhibit different patterns: small amplitude, almost imperceptible movements, possibly attributed to widespread brain damage.

Clinical Findings

  • Research outlined differences in finger tap dynamics between controls, PSP, and Parkinson’s patients.

  • Study results show PSP patients responding with reduced amplitude and minimal decrement compared to Parkinson’s disease patients.

Clinical Examples

  • Symptoms span from difficulty in performing finger taps to severe limitations in daily movements (observed through recordings).

Gait Disorders

Overview of Gait in Parkinson's Disease vs. PSP

  • Typical Parkinson's gait: stooped posture, reduced arm swing, small steps.

  • PSP patients generally maintain a more erect posture but may still present significant gait disorders due to balance issues.

Gait Freezing Phenomenon

  • Patients exhibit an inability to initiate steps, particularly in open spaces, freezing in place until a target prompts movement.

  • It's essential to recognize this behavior to develop effective therapeutic interventions.

Conclusion

Summary

  • Covered clinical diagnostic criteria for PSP including its phenotypes, distinctions between Corticobasal Syndrome and its symptoms, and their neurological implications.

  • Emphasized the importance of understanding the distinct characteristics of motor dysfunction in atypical parkinsonian syndromes.

Questions

  • Opportunity for audience to discuss or ask questions about presented materials.