2027 notes

2027 notes

Ataxia

Learning outcomes

  • outline the pathophysiology, prognosis and general management of conditions with cerebellar ataxia
  • Use the ICF framework to organise and prioritise problems, and set patient-centered goals for people with cerebellar ataxia
  • design appropriate assessment and treatment plans for people with cerebellar ataxia based on clinical reasoning and research evidence

Summary

  1. Ataxia is the loss of coordination NOT due to muscle weakness
  2. Pathophysiology and prognosis of ataxia depends on the cause of damage on the cerebellum
  3. Assessment: focus on these tests: finger-to-nose test, forearm supination-pronation test, rebound test, heel-to-shin test, berg balance scale
  4. Treatment: focus on restorative approaches (internal cues, balance, eye and muscle strength…), or else it is compensatory (external cues or equipment) or both

Definition

Ataxia: clumsiness or lack of balance or coordination that is not due to muscle weakness. (lack of coordination)

  • We need strength and coordination to work together to perform an action
  • If there is damage at the cerebellum, we must assess coordination first

Role of cerebellum

Function

  • Coordinates muscles and balance during activity and walking
    • The cerebellum detects any change in balance and movements, sends signals to the brain to adjust itself
    • Needs to time the movement of the muscles to achieve a smooth action, otherwise, it would be haphazard
    • Note the components of coordination
      • Amplitude
      • Speed (how fast)/timing (sequencing)
      • Force
      • Direction
  • Controls eye movements, speech and swallowing
  • Motor learning via practice and fine tuning
  • Higher level processing such as language and emotions

Classification of ataxia

  1. Acquired
    1. Due to external causes due to an event or a condition
    2. Acute (have a chance at recovery) or progressive/degenerative
    3. Examples: stroke, head trauma, tumour/cancer, multiple sclerosis, substance abuse
  2. Genetic
    1. Contains DNA that led to ataxia
    2. Often progressive/degenerative
    3. Examples: Friedreich's Ataxia, spinocerebellar ataxia
      1. Friedreich’s: damages the peripheral nerves, spinal cord and cerebellum
      2. SCA: family history (requires DNA testing)
  3. Idiopathic
    1. Unknown causes
    2. Example: multiple system atrophy

Specific causes and their presentations

  • Stroke
    • Occurs in the brainstem or cerebellum. Ischemia.
    • Stroke in the cerebellum vs stroke in the cerebrum has two different presentations as ataxic stroke may not present with the classical signs of slurred speech, hemiparesis, or arm drift.
    • Tests
      • Finger-to-nose: hold your index finger at arm’s length and tell them to touch their nose and reach out to touch your fingertip
        • will have incoordination, struggle with
      • Heel-to-shin: lift each leg separately and slide heel along the opposite shin
        • difficulty completing
  • Spinocerebellar ataxia
    • Rare inherited neurodegenerative heterogeneous autosomal dominant disease that mainly affects the cerebellum, hence a subset of inherited ataxia
    • Peripheral nerves, spinal cord and cerebellum are damaged
    • Needs wheelchair within 10-20 years of diagnosis
  • Friedreich’s ataxia
    • Rare inherited neurodegenerative gene
    • Lifespan is usually short but some live up to 50-60s
    • Video
      • Wide base of support
      • Unsustained horizontal nystagmus
      • Bilateral foot drop
      • Bilateral pes cavus (high arch)
      • Rapid hand opening-closing and finger tapping are slow but not ataxic
      • Supination-pronation of forearm is mildly ataxic
      • Finger-to-nose test shows mild ataxia as she approaches the target
  • Multiple system atrophy
    • Rare condition of the nervous system where there is gradual degeneration of the nerve cells in the brain -> impairment at the level of balance, movement and autonomic nervous system which controls basic functions such as breathing, digestion and bladder control
    • Lifespan is 7-10 years after first symptoms but the lifespan varies widely
    • Usually the death is not due to MSA but the secondary effects of the disease such as infection, blood clots in the lungs/embolism, or respiratory problems
    • Example: Type C
      • Facial masking increased
      • When holding arms out, they tend to drift further than before
      • Finger-to-nose progressed from unilateral to bilateral
      • Gait is more unsteady, requiring more assistance to walk

Pathophysiology of ataxia

  • Ataxic presentations differ based on the cerebellum lesions locations
    • Focal lesions follow the table
    • Diffused lesions where there are lesions at more than one site, there will be generalised symptoms
      • For vermis, there will be truncal ataxia, sparing of limbs, vertigo
      • For vestibulocerebellar, there will be gait ataxia, imbalance, vertigo
      • For lateral cerebellum hemisphere, there will be ipsilateral incoordination
    • Ataxia involves the cerebellum, its afferent or efferent pathways, vestibular system and proprioceptive pathways

Type

Neuroanatomy

Function

Ataxia or ataxic presentation

Cerebellar

Cerebellar hemisphere, including the dentate nuclei

Integration of sensory information and motor planning to perform a complex task

Ipsilateral limb ataxia (upper limb)

Dysarthria (scanning speech)

Dysdiadochokinesia

Dysmetria

Intention tremor (of the PROXIMAL limb) (essential=distal)

Midline cerebellar (vermis which includes fastigial nuclei, paravermis which includes the interposed nuclei, vestibulocerebellar)

Motor execution

Balance

Lower extremity coordination

Rapid and slow eye movements

Vestibular function

Truncal ataxia (can be made more apparent when asked to hold their arms in front or stand still)

Gait ataxia with imbalance (if removing visual cues makes it worse, refer to sensory ataxia instead)

Dysmetria

Ocular findings

Head bobbing

Vertigo

Posterior lobe (flocculonodular lobe)

Integration of information from the vestibular nuclei

Nystagmus

Postural instability

Gait ataxia

Frontal lobe of the cerebral cortex

Planning and initiating gait

Frontal ataxia (Bruns)

Magnetic gait (shuffling of feet, not lifting them off the ground)

  • Associated pathology affecting this structure can worsen ataxia

MSK (gluteal muscles)

Stabilising the hip during weight bearing

Waddling gait rather than ataxia

  • Related pathology here can worsen ataxia

Brainstem (vestibular nuclei, inferior olivary nuclei, pontine nuclei, cerebellar peduncles)

Transmits information to and fro the cerebellum

Ataxia associated with cranial nerve dysfunction and motor-sensory deficits

Sensory

Spinal cord (gracile and cuneate fasiculus, spinocerebellar tract/mossy fibres)

Sensory pathway conduction

Sensory ataxia

Sensory

Proprioceptive system and visual system

Proprioception and visual input

Sensory ataxia with Romberg’s sign (unable to stand still when eyes are closed and feet are together)

  • Pathology affecting this structure can worsen gait

Vestibular

Vestibular system (vestibular nerve, vestibular nuclei, labyrinth of the inner ear)

Sense of balance and spatial orientation

Equilibrium

Imbalance associated with vertigo and dizziness

Disequilibrium

Tinnitus and hearing impairments

Vertigo

Nystagmus

Prognosis of ataxia

  • Hereditary: usually a shorter lifespan, and if severe enough, life ends in childhood or early years
  • Progressive: symptoms worsen over time -> symptomatic treatment first
  • Acquired: find the underlying cause -> remove the triggers for better prognosis

Impairments in ataxia (ICF)

Elements of coordination

  • Amplitude
  • Speed (how fast) / timing (sequence of action)
  • Direction
  • Force

Usually the symptoms will appear ipsilateral to the cerebellar lesion

  • Example: Wallenburg syndrome/lateral medullary syndrome/posterior inferior cerebellar artery syndrome
    • Occurs when the vertebral artery or the posterior inferior cerebral artery is occluded -> infarction of lateral medulla
    • Typical presentation: motor, sensory, cognitive, speech and language deficits
    • Other presentations that rely on specific nuclei and fibres: vertigo, nausea, imbalance, sitting/postural instability, blurry vision, horizontal and/or rotational nystagmus, crossed hemisensory disturbance, reduction of ipsilateral facial pain, contralateral reduction in trunk pain and temperature sensation, temperature sensation deficits

Problems:

  • Dysmetria
    • Difficulty in achieving the desired amplitude/distance
    • Hypermetria: overshoot
      • Finger-to-nose test: press into the target as they cannot stop themselves in time
      • Eyes correcting overshoot to focus on the object
      • Large amplitude square wave jerks (1 saccade to the right, pause, 1 saccade to the left) are more specific to cerebellar ataxia
      • Ocular flutter (same as square wave but no pause) and opsoclonus (continuous and chaotic) -> cerebellar disease from paraneoplastic (neuroblastoma) or post-infectious syndromes
    • Hypometria: undershoot
      • Finger-to-nose test: pauses before the target and sometimes tries to reach further
      • Eyes taking a second to move to catch the object
    • You can have both hypermetria and hypometria
  • Dyssynergia
    • Incoordination of agonist, antagonist, and other synergistic muscles across a multi-joint system when performing a smooth action
  • Dysarthria/scanning speech
    • Difficulty in pronunciation and articulation of speech due to the muscles involved in speaking are not sequenced
  • Dysdiadochokinesia
    • Difficulty in performing rapid alternating movements
  • Rebound phenomenon
    • Difficulty regulating the force between an agonist and an antagonist (lack of check)
    • Normal: When resistance against the elbow flexion is suddenly removed, the limb will continue a short distance in the original direction of movement -> antagonist contracts after reaction time -> limb moves back in opposite direction
    • Ataxia: complete absence of this phenomena -> large distance by limb in original direction
  • Nystagmus: periodical rhythmic movements of the eye
    • Uncontrollable eye movement, usually a repetitive, slow movement in a specific direction followed by a quick adjustment to the centre
    • Focus on the motor beat and the linked coordination
      • Lateral gaze nystagmus: slow drift to midline and saccadic beating to the eccentric side
      • Upbeat nystagmus: lesion at the anterior aspect of the vermis
      • Downbeat nystagmus: lesion at the foramen magnum
  • Tremor
    • The constant oscillatory movement about a joint
    • Postural: during static sitting or standing, can be seen as truncal sway
    • Intention: during movement at the proximal limb. Tremors that happen at the end of movements are called terminal tremor.
      • Distal tremor is essential tremor

Parkinson’s disease vs cerebellar ataxia

Element

Parkinson’s disease

Cerebellar ataxia

Frequency

Regular

Irregular

Amplitude

Regular

Irregular

Limb tremor (resting)

Present

Absent

Ataxia: activity limitation

Ataxic gait: instead of thinking ‘is there an absence of coordination’, we should ask ‘how much incoordination is in this person’ = how much base of support?

  • Wide base of support
  • Irregular speed
  • Irregular step length and step width (amplitude)
  • Incoordination between hips, knees and ankle movements

Other examples of activity limitations

  • PT-focused
    • Bed mobility
    • Transfers
    • Sitting
    • Standing
    • Sit to stand
    • Walking (indoors and outdoors)
    • Stairs
    • Reaching and manipulation
  • OT-focused
    • Showering
    • Dressing
    • Toileting
    • Meal prep
    • Laundry
    • Cleaning
    • Grocery shopping

Non-motor symptoms

  • Psychiatric disorders
      • Depression
      • Anxiety is also a frequent complaint especially among patients with spinocerebellar ataxia
  • Cognitive deficits
    • This with classical cerebellar signs of motor syndromes can be explained by the disconnection at different levels of the cerebral-cerebellar circuit (Cerebral-cerebellar affective syndrome) (not about location but how it all works together)
      • Visuospatial memory
      • Language difficulties (anomia, agramatism)
      • Executive dysfunction
        • Poor planning, abstract reasoning
      • Personality changes
        • Affective swelling, disinhibition
      • Difficulty interpreting and producing logical sequences
  • Sleep disorders
      • Restless leg syndrome
      • Sleep apnea
      • Insomnia
      • Frequent daytime sleepiness can be found in some but mechanism unknown
      • Includes sleep hallucinations
  • Fatigue
    • Common symptom in neurodegenerative disorders
    • Common in multiple sclerosis, parkinson’s disease, stroke
  • Pain syndromes
    • Cramps are present in 80% of SCA patients, ¼ listed as their very first syndromes
    • 1-90 episodes a week
    • Cramps are chief complaints which is almost ⅓ of all cases
    • Lower extremities > face and trunk
      • cramps
  • Autonomic dysfunction
    • Seen in specific neurodegenerative diseases such as early multiple system atrophy
      • Symptomatic orthostatic dysfunction
      • Urinary and erectile dysfunction
      • Constipation

Assessments

They measure spatial accuracy (amplitude) and temporal accuracy (timing and speed)

General observation: eyeball pattern recognition

Assessment

Type

Results

Reason

General observation (eyeball pattern recognition)

Symptoms include

  • Hand incoordination
  • Gait disturbance/imbalance
  • Sitting or standing imbalance
  • Intention tremor
  • Slurred speech
  • Loss of sensation
  • Paresthesia

Serious or life-threatening causes

  • Headache
  • Nausea
  • Vomiting

Age and gender

Children: cerebellitis

Younger people (women): migraine

Onset

Acute: needs special attention as can be fatal

Chronic: primary tumor

Intermittent pattern: transient ischemic attack, multiple sclerosis, inherited episodic ataxia

Differential diagnosis

Mental status

Site of motor corrdination

Communicates with cerebrum for higher cortical functions

Cranial nerve examination

Abnormal pursuit and saccade

Extraocular dyskinsia

Facial and tongue fasciculations: SCA3

Severe tongue atrophy and fasciculations: SCA 36

Vestibular signs

Vertigo, slow nystagmus

Veer to ipsilateral

Hearing loss for inner ear issues

Cerebellar signs

Gait: tandem stance or walking are sensitive -> veer to same side, wide base in standing

Extrapyramidal signs

Chronic progressive ataxia

Indicates spread beyond cerebellum and brainstem

SCA and parkinsonism (once striatum is involved, it is not responsive to levodopa)

Strength

Symmetric proximal: myopathy

Distal muscle weakness: generalised neuropathy

Degree of ataxia can be explained by muscle weakness

Proprioceptive sensory system

Positive romberg sign

Worse when visual cues are removed

If pure cerebellar, no diff

Spinocerebellar tracts: sensory input to cerebellum, hence sensory ataxia

Heel-to-shin (NIHSS item 10)

Impairment

Finger-to-nose (NIHSS item 10)

Impairment

Rebound test

Impairment

Forearm supination-pronation test

Impairment

SARA

Impairment

Activity limitation

ICAR

Impairment

Activity limitation

Berg balance scale

Activity limitation

Impairments and activity levels

  • SARA

​​

  • ICARS

Activity scale

  • Berg balance scale

Research evidence (Assessment)

Article

Systematic review of psychometric properties of balance measures for cerebellar ataxia

Balance outcome measures in cerebellar ataxia: a Delphi survey

Authors

Stanley J winder

Catherine M smith

Leigh A hale

Leica S claydon

Susan L whitney

Poonam Mehta

Stanley J winder

Catherine M smith

Leigh A hale

Leica S claydon

Susan L whitney

Population

Mostly acquired ataxia (multiple sclerosis), needs more non-genetic ataxia

Cerebellar ataxia patients by 30 experts representing 10 countries

Intervention

Berg balance, activity-specific balance confidence scale

SARA

TUG

BBS

Available at low cost, require little equipment, and easy to perform

Outcome

COSMIN: consensus based standards for the selection of health status Measurement Instruments

Acceptable reliability and validity of measures but responsiveness is yet to be determined

But quality of methodology in studies is mostly poor

Quality of studies investigating psychometric properties of balance subcomponents: Poor to excellent

MCID not determined

75% consensus

But psychometric properties have not been tested in genetic ataxia and responsiveness have not been tested

Treatment approaches

  1. Restorative: impairment (80%)
    1. Eye and strengthening exercises, internal cues, balance
    2. Surgical and medical procedures for CNS recovery
      1. For stroke, they need this to be medically stable. To retore function, they will then need to rely on restorative methods
      2. Isoniazid pyridoxine, cannabis based medication, baclofen
      3. Thalamotomy, transcranial magnetic stimulation
  2. Compensatory: activity limitation and participation (20%)
    1. Environment such as tapes, visual, auditory, propriceptive
      1. Strategically placed weights to provide proprioceptive feedback and reduce tremors, improve motor functions and awareness of body position
    2. External such as walking aids
      1. Can be used to correct a movement and then be removed to facilitate restorative
      2. Parallel bars for walking

Combine restorative and compensatory

All depends on

  • Prognosis: acute vs degen
  • Severity: mild vs severe
  • Stage of rehab: early vs late

Other examples of treatment

Paper

Findings

Meaning

Consensus paper: ataxic gait, 2022

Training

  • Can adapt to perturbations at the waist or feet due to fast reflexes from neural pathways down from cerebellum
  • Can benefit from intense rehabilitation sessions
  • Benefits best from rehab that involves multi joint coordination and balance while receiving vestibular, somatosensory and visual inputs

Split belt treadmill paradigm for locomotive adaptation

  • Same speed -> adaptation period to ⅔:1 where slow foot takes a longer step -> same speed
  • Severe gait: unable to adapt walking patterns on treadmill or interlimb coordination but improved coordination in a leg
  • Mild-mod: similar interlimb coordination and step length

Robot assisted gait training

  • With conventional > just conventional: standing, balance function, ADL independence

Non-invasive brain stimulation + robotics + metaplasticity protocol: improvement in function of heel-to-shin, gait, sitting, and stance

Dynamic movement orthosis: soft and flexible, improves gait parameters without restriction (decrease in trunk oscillations and body sway, decrease in double support phase and swing variability, increase in swing phase, increase in pelvic and knee ROM, increase control of knee during swing

When training, focus on intense multi-factor rehab.

Mild-mod ataxia > severe ataxia in interlimb coordination and step length

But they all can adapt walking patterns

Robot (+ non invasive brain stim) + conventional is ok

DMO is good

Gait ataxia – specific cerebellar influences and their rehabilitations

2013

FACTORS CONTRIBUTING TO ATAXIC GAIT

Localisation of cerebellar functions

  • Vermis: upright posture, dynamic stability, extensor tone, extensor and flexor muscle activity, eye movements
  • Intermediate zone: precise limb movements (direction, amplitude and speed of agonist and antagonist movements)
  • Lateral zone: not as impt but is thought to adapt to new environment or when strong visual guidance is needed

Balance impairments

  • More impact than feet incoordination
  • Gait parameters in stride length and angles of the hip, knee and ankle

Intralimb coordination

  • Control of limb dynamics and intralimb variability: temporal variability
  • Balance: gait parameters like step width and lateral sway

Oculomotor dysfunction

  • Vision has a great impact on the gait
  • Saccadic and foot placement task could be improved by prior practice by making saccadic eye movements towards the target

Dual tasking (cognitive and motor)

  • Accentuates gait disorders in neurological patients in general
  • Lateral cerebellum has involvement in working memory and complex motor tasks
  • Mild ataxia patient’s gait disturbance is only apparent in complex gait tasks like tandem walking

Adaptation of walking pattern

  • Intermediate cerebellar (interposed nuclei and adjacent dentate nuclei) influences lower limb multi joint limb control (leg placement)
  • In split belt treadmill, cerebellar patients show normal reactive changes but cannot make predictive changes in temporal aspects of interlimb coordination

Ataxic gait rehab

  • Cause and site of lesion
    • Focal: unaffected parts compensate
      • Effects of neural plasticity are more effective as it is not competing with degeneration
      • site>extent of lesion: deep cerebellar nuclei lesion cannot be compensated
    • Degen: hard to treat due to progressive nature and influence on all parts of cerebellar
      • Train increasingly demanding tasks benefit them
        • Increasingly demanding gait and balance training: less walking aids used =postural stability
        • Training posture and gait: benefits could be meaningful and persisted after 1 year
      • Activate and demand control from visual, somatosensory and vestibular inputs to react to different circumstances

Systematic review of characteristics associated with cerebellar ataxia

2018

P: 21 studies of quantitative gait assessment with 408 ataxic and 403 normal

Findings:

  • Increase in speed (speed dependent changes also seen more as normal people age)
    • Increase: Cadence, step and stride length, swing phase %
    • Decrease: stance % and double leg support % (DLS)
  • Differences in speed ataxia vs normal (multiple sclerosis) related to falls risk
    • Fast: more sensitive to gait changes -> swing, stance and DLS
    • Slow: increased variability
  • Disease progression and gait
    • Increase: gait variability (can predict loss of independent gait), cadence, stride and step length, DLS phase
      • Postural instability
    • Decrease: swing

Rehabilitation of ataxic gait following cerebellar lesions: applying theory to practice

Stability of the Trunk in Patients with Degenerative Cerebellar Ataxia During Walking

2016

  • The older the person, the worse the trunk instability
  • The less the trunk instability, the worse the postural control and disease severity
    • Those who have greater instability adopt compensatory measures to co contract the agonist and antagonist muscles to stabilise the trunk
    • Compensatory mechanisms are energetically expensive

Evidences (treatment)

Article

Rehabilitation for individuals with genetic degenerative ataxia: a systematic review

Cerebellar ataxia rehabilitation trial in degenerative cerebellar disease

Authors

Sarah c Milne 2017

LOUISE A CORBEN

NELLIE GEORGIOU-KARISTIANIS

MARTIN B DELATYCKI

EPPLE M YIU

Miyai I

Ito M

Hattori n

Mihara m

Hatakenaka m

Yagura h

Sobue g

Nishizawa m

Population

17 publications: 5 RCTs

Degenerative ataxia

Moderate to low quality studies

42 pt with pure cerebellar degeneration

Exposure

Rehab included coordination and balance training , multi-faceted inpatient rehab, a cycling regime, balance exercises with technology assisted biofeedback, respiratory muscle training, treadmill training

2 studies examined adjuncts

2h inpatient physical and occupational therapy with focus on coordination, balance, ADLs on weekdays

1h on weekends

4 weeks

Outcome

Emerging evidence (15/17) that rehab can improve gait, function, balance and/or ataxia for genetic degenerative ataxia (consistent despite quality)

BUT less than half included assessment of long term outcomes and the follow up time frames varied

  • 1 RCT support inpatient rehab for ambulant individuals with pure cerebellar ataxia but more high-quality multisite RCTs needed for efficacy of rehab interventions
  • Esp for afferent ataxia and those who are non-ambulant
  • Therapies should include multifaceted interventions targeting more than one area of impairment

All except the feasibility study and compensatory OT intervention, has within group improvement in at least one outcome of gait, function, balance and/or ataxia

Miyai et el: most conclusive evidence (NHMRC level 2) for between-group improvements in ataxia, function, number of falls and balance after 4 weeks of inpatient rehab for those with more pure cerebellar ataxia

Assessment and rating of ataxia

  • Function independence measure
  • Gait speed, cadence
  • Functional ambulation category
  • Number of falls

significantly greater functional gains in ataxia, gait speed, ADLs

Short term benefits

BUT functional status declined to baseline in 24 weeks, but gains are still maintained in more than half