Neurology Quiz: Ataxia Disorders

Ataxia

Ataxia is the loss of coordination of voluntary movements

It may or may not be accompanied by disequilibrium, but does not include motor weakness

Cerebellum

The cerebellum is a part of the brain responsible for coordinating movement

• It has three main lobes:

vestibulocerebellum (archicerebellum)

flocculonodular lobe

spinocerebellum (paleocerebellum)

anterior lobe

cerebrocerebellum (neocerebellum)

posterior lobe

The cerebellum maintains balance and postural control

It assists in error detection and modulating muscle tone

It plays a vital role in coordination, fine movement, action preparation, and timing.

It receives input from cortical, sensory, and proprioceptive areas, then projects this information to the thalamus

Damage to the cerebellum can cause significant motor impairment

The cerebellum receives sensory input and guides movement in a feedback and feed-forward manner

Feedback control systems continuously compare desired output to actual output to make adjustments during the movement

Feedback & Feed-forward Control

Feedback controllers continuously adjust the actual output to match the desired output

Feed-forward controllers send precise commands without feedback, allowing quicker movement execution

Coordination and Comparator

The cerebellum acts as a comparator checking voluntary signals against sensory signals from movement

Corrective feedback is provided to motor pathways if a mismatch is found

A cerebellar lesion may prevent the cerebellum from correcting movement errors leading to dysmetric movements

Compensator and Adaptive Control

The cerebellum acts as a compensator by adjusting reflexes to anticipate future movement

This is part of an adaptive feed-forward control system using prior sensory and motor output for prediction

Cerebellum Functions

Regulation of equilibrium

Maintaining muscle tone, affecting axial & proximal limbs. A lesion can lead to hypotonia.

• Regulation (coordination) of voluntary movements- uses mechanisms including:

Comparator and error correction

Damping mechanism

Planning movement sequence & timing

Damping mechanism- the cerebellum sends braking signals to prevent overshooting of movements

A damaged cerebellum may result in intention kinetic tremor

Ataxia Types

Cerebellar ataxia

Sensory ataxia

Vestibular ataxia

Mixed ataxia

Hysterical ataxia

Cerebellar Ataxia Causes

Lesions to the cerebellum and/or its connections

Vestibulo-cerebellar dysfunction

Spino-cerebellar dysfunction

Cerebro-cerebellar dysfunction

Idiopathic (age-related)

Symptomatic (vascular, inflammatory, traumatic, or tumor)

Heridofamilial (Friedreich's or Marie's ataxia)

Ataxia Symptoms (Friedreich's and Marie's)

Age of onset: Friedreich's is in the 1st decade. Marie's is in the 2nd and 3rd decades

• Cerebellar manifestations/deficits:

Friedreich's: mainly archicerebellar (walking & balance issues); spinocerebellar & pyramidal tract affected. Minimal or no deficits in deep reflexes & no impaired sensation.

Marie's: mainly neocerebellar (incoordination); pyramidal tract affected. Deep reflexes tend to be exaggerated, but sensation is preserved.

Sensory Ataxia

Can be observed in hereditary ataxias like Friedreich's

Can occur in other conditions like peripheral neuropathy, posterior column issues, brainstem lesions, thalamic syndrome, or parietal lobe lesions

Vestibular Ataxia

Ataxia due to lesions in the vestibular division of the 8th cranial nerve (e.g., Meniere's disease, labyrinthitis, acoustic neuroma)

Symptoms commonly include vertigo, tinnitus, and deafness.

Cerebellar Syndromes

Archicerebellum (vestibulocerebellum syndrome)- symptoms include problems with balance & posture (swaying, falling) and wide-based gait

Paleocerebellum-spinocerebellum syndrome- causes hypotonia & hyporeflexia impacting posture and coordination

Neocerebellum (cerebrocerebellum) syndrome- also causes hypotonia & hyporeflexia, affecting distal and proximal issues

Ataxia Symptoms- Other

Asthenia (generalized weakness) is a less common symptom, most prominent in patients with extensive & deep lesions

• Incoordination:

Dysmetria: inability to judge range/direction of movement

Intention tremor (kinetic tremor): oscillation of movement that increases toward the end of the movement; seen in ongoing movements, not at rest.

Titubation: tremor affecting the head, upper trunk, and legs, follows lesion of the vermis

Postural truncal tremor: tremor affecting legs and lower trunk related to lesions of anterior cerebellar lobe.

Decomposition of complex movements: distinct sequences rather than smooth movements

Rebound phenomenon: patient cannot quickly stop ongoing movement, limb forcefully moves or hits body

Dysdiadochokinesis: slow, irregular, and clumsy movements of rapidly alternating movements (such as pronation/supination)

Ataxia problems- Other

Problems with balance (postural sway, poor equilibrium)

Instability around pelvis which interferes with weight-bearing control

Orofacial dysfunction: nystagmus and dysarthria

Issues with visual fixation, head/trunk control, leading to problems with gait (wide-based or drunken gait)

Evaluation Principles

Bilateral assessments needed, even for unilateral lesions

Assess functional capabilities in a quiet environment, consideration of patient's age and emotional state

Examination of functional activity to include assistance needed and time to complete

Ataxia Assessment

Motor assessment (muscle tone, muscle tests)

Sensory assessment (superficial and deep sensation)

Range of motion (ROM)

• Orofacial function (facial expression, lips, jaw closure, swallowing, speech) Coordination of movement assessed through:

Coordination (basic functional capabilities with equilibrium subtypes)

Alternate/reciprocal motion

Movement composition/synergy

Movement accuracy (e.g., dysmetria)

Fixation/limb holding

Equilibrium & postural holding

Special tests: Finger-to-nose, finger-to-finger, finger-to-doctor's finger, heel-to-knee, tandem gait, and Romberg's Test

Gait Assessment

Categorize gait according to lesion site (e.g., wide-based/drunken to unsteadiness/deviation to one side/zigzag):

Evaluate gait by speed, direction changes, balance loss frequency/distance walked & assistance needs

Goals of Treatment

Postural stability

Functional gait

Accuracy/coordination of limb movements

Treatment Principles

Graduated from simple to complex

Focus on proximal stability progressing to distal segments

Compensation aids and devices/assistive techniques when needed

Home exercise programs & recreation activities

Methods to improve proprioception

PNF techniques (rhythmic stabilization, reversal techniques, approximation)

Resistive exercises on varied surfaces (with eyes open/closed)

Using weighted objects, balance boards, and balls

Specific Techniques of PNF

Slow reversal (isotonic contraction of agonist and antagonist)

Slow reversal hold (isotonic contraction of antagonist followed by isometric contraction of antagonist then same agonist sequence)

Repetition of Assessment

Non-equilibrium tests, modification of range/speed/eye status during tests

Combined PNF patterns (bilateral symmetrical, bilateral asymmetrical, reciprocal same diagonal, reciprocal opposite diagonal).

Training of Coordination (5 phases)

Perception (correct performance) through sensory input (tactile & visual)

Precision (simplifying movements)

Perceptual practice (repetitive activity)

Peak performance- determine and practice movements below peak to prevent fatigue

Progression- revise performance as improvement occurs, transition to a functional goal

Vertigo Treatment Exercises

Vertigo is a sensation of body rotation, often paired with substitution and adapting vestibular function.

Vestibular habituation exercises

Cawthorne Cooksey exercises

Vestibular Habituation Training

Repeated stimulation of receptors causing vertigo

Determine position/movement eliciting vertigo

Select/practice movements which elicit vertigo

Repeat exercises five times twice daily

Maintain vertigo-eliciting positions until resolved

Cawthorne Cooksey Exercises

Graduated head and eye movements to train visual & somatosensory systems for vestibular adaptation

Exercises progress from least to most likely to elicit vertigo

Repeat 10-20 times per day, progressing from slow to faster movements

Methods for decreasing tremors/nodding/titubation

Tonic holding

Alternative isometric exercises

Weight-bearing exercises

Approximation

Weights on ankles/wrists

Rhythmic stabilization

Alternative isometric exercises

Asthenia Treatment

Graduated resistive exercises to strength muscles resisting gravity

Endurance exercises

Gait Training

Walk in parallel bars or using a walker

Use mobility aides, canes etc to allow reciprocal movement of arms & legs

Properly time leg/arm movements

Use of supportive aids

Use supportive equipment when restorative physical treatment is insufficient to improve function levels

Orofacial Training (Mirror)

Laryngeal wall movement

Jaw tapping for stimulation of swallowing

Tongue vibration

Applying ice to the face for relaxation

Deep breathing before speaking increases sound volume

Test your knowledge on ataxia disorders, including Friedreich's ataxia and Marie's ataxia. This quiz covers clinical manifestations, symptoms, and treatment goals related to these conditions. Gain insights into the various types of ataxia and their unique features.