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Introduction

  • Speaker: Hugh Morris, Neurology Consultant with interests in atypical parkinsonism

  • Objective: To discuss clinical features of atypical parkinsonian syndromes and their neuroanatomical correlates.

Atypical Parkinsonism Overview

  • Definition: Atypical parkinsonian syndromes are conditions that exhibit symptoms similar to Parkinson's disease but have distinct clinical features and prognosis.

  • Common Types:
      1. Progressive Supranuclear Palsy (PSP)
      2. Corticobasal Degeneration (CBD)

Expected Learning Outcomes

  1. Understanding gaze palsy, specifically supranuclear gaze palsies.

  2. Examination of apraxia, bradykinesia, and gait disorders in these conditions.

  3. Comprehension of underlying brain systems involved in these manifestations.

Clinical Features of Atypical Parkinsonian Syndromes

  • Presentation involves a combination of motor symptoms and cognitive challenges.

  • Emergence typically follows initial diagnosis as Parkinson's disease, potentially misleading diagnosis, and delayed treatment.

Progressive Supranuclear Palsy (PSP)

  • Definition: PSP is recognized as the most common atypical parkinsonian syndrome.

  • Pathology: Classified as a pure tauopathy involving deposition of tau protein leading to neurofibrillary tangles in neurons and astrocytes.

  • Prognosis: Rapid decline; patients typically experience significant life-limiting symptoms and a lifespan of approximately 6-8 years post-onset.

Clinical Diagnostic Criteria for PSP

  • Based on the Luthar Society clinical diagnoses, the diagnostic features for PSP include four key domains:
      1. Ocular motor dysfunction
      2. Postural instability
      3. Akinesia (slowing of movement)
      4. Cognitive dysfunction

  • Ocular Motor Dysfunction: Characteristic issue involves gaze palsy, particularly effects on vertical eye movements; Patients often feel visual impairments that stem from erroneous eye movement control.

  • Postural Instability: Frequent falls and balance problems, suggesting significant impairment in motor control.

Phenotypes of PSP

  • The principal phenotype is PSP Richardson syndrome (PSPRS) characterized by:
      1. Vertical gaze palsy
      2. Frequent falls
      3. Symptoms of akinesia.
      4. Other variants include PSP Parkinsonism and PSP with progressive gait freezing.

Corticobasal Degeneration (CBD)

  • Definition: Another form of tauopathy, involves degenerative changes primarily in the frontal and parietal cortices, and the basal ganglia.

  • Symptoms: Asymmetric motor symptoms prevalent; includes rigidity, dystonia, myoclonus, and notably apraxia.

Apraxia

  • Definition: A disorder characterized by difficulty in carrying out skilled movements, despite having the physical capacity to do so.

  • Two key types elaborated:
      1. Ideomotor Apraxia: Difficulty performing learned movements upon command.
      2. Limb Kinetic Apraxia: Difficulty with the fractional movements or moving individual fingers.

  • Testing for Apraxia: Involves asking patients to perform familiar movements, observing for delays or inaccuracies.

Specific Features of Apraxia

  • The sequencing of movements can become confused, where actions often compensate with the unaffected side.

  • Patients may demonstrate alternative movement strategies (like using fingers instead of tools).

Gait Disorders in Atypical Parkinsonism

  • Bradykinesia: Notable in both PSP and Parkinson's disease but distinct in presentation:
      - Patients with PSP may display a different type of bradykinesia characterized by small, rapid movements lacking the gradual slowing seen in Parkinson's patients.

Gait Patterns

  • Parkinson's Disease Gait: Characteristically stooped posture, reduced arm swing, small steps, and progressive decrement in stride size over time.

  • PSP Gait: Patients appear erect with larger steps and pronounced balance issues, often needing assistance or mobility aids.

Neurological Underpinnings

  • Discussed concept of supranuclear gaze palsies, ocular apraxia, and variations in pathways and brain structures essential for normal motor control.

  • Importance of the frontal eye fields, brainstem nuclei, and their roles in coordinating voluntary eye movements versus reflexive ones.

Gait Freezing Phenomenon

  • Definition: A specific issue within PSP where patients may freeze or refuse to initiate steps, often exacerbated by environmental changes or transitions.

  • Treatment trials using cholinesterase inhibitors and neurosurgical interventions for addressing gait disorders have proven largely ineffective.

Summary of Learning Points

  • Reviewed additional features associated with PSP and CBD, emphasizing clinical appreciation for differential symptoms.

  • Encouraged identification of the nuanced differences in gait and bradykinesia between atypical parkinsonism and typical Parkinson's disease.

Conclusion

  • Acknowledged that the exploration of atypical parkinsonism requires a considered approach to diagnosis — based on clinical presentation and differential pathology.

  • Ongoing understanding of individual brain areas in this context remains crucial for future therapeutic endeavors and patient management.