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Introduction

  • Presenter: Hugh Morris, neurology consultant with interest in atypical parkinsonism.

  • Overview of Topics: Clinical features of atypical parkinsonian syndromes, motor systems, brain systems related to atypical features, specific focus on:
      - Gaze palsy (specifically supranuclear gaze palsies)
      - Apraxia
      - Bradykinesia
      - Gait disorders

  • Aim: Understand physiology and neuroanatomy underlying these features.

Atypical Parkinsonian Syndromes

  • Definition: Atypical parkinsonian syndromes (also referred to as Parkinson's plus syndromes) differ from prototypic Parkinson's disease.

  • Prevalence: Atypical conditions like Progressive Supranuclear Palsy (PSP) occur in about 10% of cases initially thought to be Parkinson's.

  • Rapid Progression: Symptoms lead to loss of speech, swallowing, and walking abilities, often resulting in death within 6 to 8 years of symptom onset.

  • Malignant Nature: Conditions often misdiagnosed as Parkinson's, indicative of their aggressive nature.

Progressive Supranuclear Palsy (PSP)

  • Description: Most common atypical Parkinsonian syndrome, classified as a pure tauopathy with tau protein deposition as key pathology.

  • Pathology: Presence of neurofibrillary tangles in neurons and astrocytes.

Clinical Diagnostic Criteria (Luther Society Criteria)

  • Four diagnostic domains:
      1. Ocular motor dysfunction - the defining feature of PSP.
      2. Postural instability - results in frequent falls.
      3. Akinesia - slowing of movement.
      4. Cognitive dysfunction - often includes frontal cognitive impairments.

Common Symptoms of PSP

  • Ocular Symptoms:
      - Difficulties in eye movements particularly affecting reading, emphasis on gaze palsies.
      - Gaze palsied patients may initially seek help from opticians due to poor vision without physical abnormalities.

  • Postural Instability:
      - Frequent falls, assessed using the pull test indicating balance issues.

  • Bradykinesia:
      - Patients may experience freezing of gait, particularly when attempting to initiate movement.

  • Cognitive Dysfunction:
      - Frontal cognitive dysfunction causing disinhibition, apathy, and executive function difficulty.

PSP Phenotypes

  • PSP Richardson syndrome (PSPRS): Characterized by all typical symptoms and features including ocular motor and motor phenotypes.

  • Other types: PSP Parkinsonism and PSP with progressive gait freezing.

Corticobasal Syndrome

  • Description: Another tauopathy involving deposition of tau proteins, primarily impacting cortex and basal ganglia.

  • Clinical Features:
      - Asymmetrical symptoms more dominant on one side of the body.
      - Rigidity, dystonia, myoclonus, and difficulty with purposeful movements (Apraxia).
      - Alien limb phenomenon - patients experience their limbs moving involuntarily due to loss of proprioceptive feedback.

Apraxia in Detail

  • Definition: Inability to perform skilled movements despite normal motor power; often linked to frontal and parietal lobe damage.

  • Diagnostic Methods: Testing patients with simple gestures, revealing coordination issues despite intact sensation and power.

  • Other features: Loss of cortical sensory function, challenges in recognizing objects by touch.

  • Variant conditions may produce similar features, emphasizing the importance of neuroanatomy vs. pathology.

Exclusion Criteria for Corticobasal Syndrome

  • Importance of brain scans:
      - MRI necessary to eliminate the possibility of strokes, tumors, or alternative conditions mimicking symptoms (e.g., Alzheimer’s).

Clinical Signs and Eye Movements

  • Understanding Eye Movement Disorders:
      - Saccadic and smooth pursuit movements are controlled by different pathways in the brain.
      - The frontal eye fields initiate voluntary eye movements, while brainstem nuclei execute them (e.g., rostral interstitial nucleus of the medial longitudinal fasciculus).

Supranuclear Gaze Palsy

  • Definition: Impairment relating to deficits above ocular motor nuclei.

  • Distinction of eye movement types: difficulty accessing voluntary control while controlled reflexive movements remain intact.

  • Apraxia of eye movements as a significant clinical feature.

Clinical Evaluation of Patients

  • Eye movement tests demonstrating gradual impairment in initiating commands due to cortical involvement.

  • Distinctions between normal reflexive responses and voluntary control.

Bradykinesia

  • Definition: Characterized by generalized slowness across all movements, differing patterns in PSP versus Parkinson's disease.

  • Characteristics in PSP:
      - Fast, small amplitude movements with minimal decrement, contrasting with Parkinson's where movements progressively slow and decrease in size when serially repeated.
      - Research suggests different anatomical correlates affecting movement patterns in both conditions.

Gait Disorders

  • Comparison between typical Parkinson's gait and PSP gait disorders:
      - Typical Parkinson's gait: stooped posture, reduced arm swing, small steps.
      - PSP gait characteristics: erect posture, larger steps, frequent need for corrective foot placement.

  • Specific gait challenges observed in PSP, such as freezing episodes and their environmental triggers.

Observations from Clinical Videos

  • Examples of both gait types benefiting from targets to guide movement, highlighting the complex nature of motor control in these conditions.

Conclusion

  • Summary of learning goals:
      - Differentiation between diagnosis and clinical features of PSP syndromes.
      - Understanding how various brain regions contribute to clinical signs of neurodegenerative diseases.

  • Closing thanks for attention.