Ataxia

Aka: Ataxia, Incoordination, Muscular Incoordination

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II. Definitions

  1. Ataxia
    1. Failure to produce smooth intentional movements (Incoordination)
  2. Disequilibrium
    1. Disturbance of postural balance
  3. Dyskinesia
    1. Difficulty performing voluntary movement
    2. Includes hyperkinesia (too much movement) and hypokinesia (too little movement)

III. Pathophysiology

  1. Ataxia is a Movement Disorder (in the hyperkinesia sub-category)
  2. Cerebellar lesions affect the ipsilateral body
  3. Mechanisms by which Cerebellum coordinates movement
    1. Vestibular system inputs (head position in relation to body)
    2. Visual cortex
    3. Extremity proprioception

IV. Causes: Cerebellar or Central Nervous System

  1. Cerebellar lesion or neoplasm
  2. Intracranial Hemorrhage
    1. Arteriovenous Malformation (even without bleeding)
    2. Cerebellar Hemorrhage
  3. Cerebrovascular Disease
    1. Cerebellar infarction
    2. Vertebrobasilar Insufficiency
    3. Vertebral Artery Dissection
  4. Infection
    1. Meningoencephalitis
    2. Cerebellar Abscess
    3. Viral Cerebellitis (children)
      1. See Ataxia in Children
      2. Acute Demyelinating Encephalomyelitis (ADEM)
      3. Acute Cerebellar Ataxia
  5. Post-infectious
    1. Acute Cerebellar Ataxia
    2. Guillain-Barre Syndrome (or Miller Fisher Syndrome variant)

V. Causes: Extra-cerebellar or systemic

  1. Autoimmune Conditions
    1. Acute Disseminated Encephalomyelitis
    2. Hashimoto Thyroiditis (or Encephalitis)
    3. Celiac Sprue
    4. Multiple Sclerosis
  2. Vitamin Deficiency
    1. Vitamin B12 Deficiency
    2. Thiamine deficiency
  3. Toxic ingestion
    1. Alcoholic Cerebellar Degeneration
      1. Chronic Ataxia (especially gait and legs, and to a lesser extent arms, speech, eyes)
      2. Associated with Memory Loss and Polyneuropathy
      3. Contrast with the acute Alcohol related Ataxia of Thiamine deficiency (Wernicke's Encephalopathy)
    2. Carbon Monoxide Poisoning
    3. PesticidePoisoning
    4. Arsenic Poisoning
    5. Lead Poisoning
    6. Mercury Poisoning
  4. Metabolic Disease
    1. Hypoparathyroidism
    2. Hypothyroidism
    3. Hyperthermia

VI. Causes: Anatomic

  1. Frontal Lobe Lesion (affects cortico-cerebellar connections)
    1. Frontal Lobe lesions or neoplasms (e.g. meningioma, glioma)
      1. Frontal Ataxia may present with falling backwards
      2. Associated with Perseveration, Incontinence and slowed thinking
    2. Anterior Cerebral Artery syndrome
      1. Results in ischemic Frontal Lobe stroke
    3. Hydrocephalus (e.g. Normal Pressure Hydrocephalus)
      1. Frontal horns of the Lateral Ventricles enlarge and affect leg-related fibers
      2. Associated with Memory Loss and Incontinence
  2. Sub-cortical Lesion (affects cortico-cerebellar connections and pyramidal tracts)
    1. Multiple Cerebrovascular Accidents
      1. Associated with emotional lability, Dysarthria and Dementia
    2. Ataxic Hemiparesis
      1. Lacunar Infarct in the Internal Capsule or pons
  3. Brainstem Lesion (affects cerebellar tracts)
    1. Cerebrovascular Accident
    2. Multiple Sclerosis
  4. Cerebellar Lesions
    1. See Cerebellar causes above (e.g. Cerebellar Hemorrhage, Cerebellar infarction, Cerebellar Neoplasm)
    2. Spinocerebellar Degeneration (e.g. Friedrich's Ataxia)
    3. Alcoholism (chronic Alcoholic Cerebellar Degeneration or Acute Thiamine Deficiency)
    4. Acute cerebrellitis (viral or post-viral)
  5. Spinal cord (affects Posterior Columns or pyramidal tracts)
    1. Cervical Spondylosis
      1. Cervical Myelopathy with neck and arm pain
    2. Multiple Sclerosis
    3. Vitamin B12 Deficiency
      1. Affects Posterior Columns and lateral columns
      2. Progresses from generalized weakness and Paresthesias to leg stiffness and Ataxia
    4. Syringomyelia
    5. Spinal cord tumor
    6. Spinocerebellar degeneration
    7. Tabes Dorsalis (Tertiary Syphilis)
    8. Amyotrophic Lateral Sclerosis (ALS)
  6. Peripheral Nerve (affects dorsal roots and polyneuritis)
    1. Guillain-Barre Syndrome
  7. Muscle (affects Muscle Weakness)
    1. Myopathy (e.g. Polymyositis, Hypothyroidism, Muscular Dystrophy)
    2. Acute Muscle-related causes of Ataxia
      1. Toxins (see above)
      2. Sickle Cell Crisis
      3. Systemic Lupus Erythematosus
    3. Chronic rare Muscle-related causes of Ataxia
      1. Charcot-Marie-Tooth Disease
      2. Ramsey Hunt Syndrome
      3. Huntington's Chorea

VII. Symptoms

  1. Ataxia-related chief complaints
    1. Dizziness
    2. Weakness
    3. Incoordination
    4. Falls
    5. Fine motor or gross motor difficulties

VIII. Precautions

  1. Confirm with patient and family what changes are new

IX. Exam

  1. Cranial Nerve Exam
  2. Motor Exam
  3. Alternating hand movements
    1. See Rapid Alternating Movements (Diadochokinesia)
  4. Gait Exam
    1. Observe for listing or falling to one side (Cerebellar Gait)
    2. Also observe for falling to one side while sitting with eyes open (truncal Ataxia)
    3. See Gait and Balance Evaluation in the Elderly
    4. See Gait Evaluation in Children
  5. Coordination testing
    1. Observe for for dysmetria, overshooting target or Intention Tremor
    2. Finger-Nose-Finger
    3. Heel-Knee-Shin
  6. Proprioception (Peripheral Nerve or sensory deficit)
    1. Romberg Sign
  7. Vestibular Exam
    1. See Nystagmus
    2. Observe for opsoclonus (rapid, jerking saccades of the eyes independent of head position changes)
  8. Speech Exam
    1. Listen for halting, hesitancy or garbled speech
    2. Listen for scanning speech (breaking up words on their syllables)

X. Signs

  1. Cerebellar Gait
    1. Staggering, wide-based, unsteady gait
  2. Dysmetria
    1. Abnormal Finger-Nose-Finger
    2. Typically seen in hemispherical lesions
  3. Truncal Ataxia
    1. Unable to sit or stand without support
    2. Due to midline cerebellar disease (vermis)
  4. Dysdiadochokinesia (DDK)
    1. Inability to perform Rapid Alternating Movements
  5. Proprioception disorder
  6. Abnormal Nystagmus

XI. Imaging

  1. Indications for emergent imaging
    1. Acute Ataxia (onset within prior 72 hours)
    2. Altered Level of Consciousness
    3. Asymmetric or focal neurologic deficits (including Cranial Nerve deficits)
    4. Traumatic Injury
  2. CT Head
    1. Mass effect suspected
    2. Hydrocephalus
    3. Intracranial Hemorrhage
    4. Acute Head Injury
  3. MRI Brain
    1. Most cases of Pediatric Ataxia
    2. Posterior fossa lesion suspected
    3. Chronic Ataxia

XII. Diagnostics

  1. Lumbar Puncture
    1. Indicated for suspected CNS Infection
    2. Obtain CNS Imaging first if any concern for mass lesion
  2. Toxicology Screening (including Blood Alcohol Level)
    1. Highest yield in children with Ataxia
  3. Pulmonary Function Tests
    1. Guillain-Barre Syndrome suspected

XIII. Management

  1. Neurology Consultation
  2. Emergent neurosurgery Consultation indications
    1. Cerebellar Hemorrhage
    2. Cerebellar infarction
    3. Obstructive Hydrocephalus
  3. Empiric medications
    1. Thiamine 100 mg IV daily (adult dose)
    2. CNS Infection suspected (esp. children with Seizure)
      1. Acyclovir and Antibiotics for suspected Meningitis and Encephalitis
    3. Acute Demyelinating Encephalomyelitis (ADEM) suspected
      1. See Ataxia in Children
      2. Methylprednisolone 20-30 mg/kg/day (up to 1 gram daily) for 3-5 days, then taper over 4-6 weeks
      3. IVIG and Plasmaphoresis have been used in refractory cases

XIV. References

  1. Streich and Huff (2015) Crit Dec Emerg Med 29(2): 2-9
  2. Weiner and Levitt (1989) Ataxia, Neurology for the House Officer, 4th ed, Williams and Wilkins, p. 124-8
  3. Salas (2010) Emerg Med J 27(12): 956-7 [PubMed]

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