Ataxia and Gait Disorders Flashcards
In very general terms, what are the two types of ataxia?
cerebellar ataxia sensory ataxia (loss of position sense)
How can you tell where in the cerebellum a lesion has occurred?
vermal lesion = truncal and gait ataxia
hemispheric - ipsilateral limb ataxia
How does an acute cerebellar hemorrhage or infarct typically present?
abrupt onset of vertigo, vomiting and inability to walk
the level of arousal may be depressed if there is compression of the fourth ventricle with hydrocephalus or if there is pressure on the brainstem
What is the most common cause of acquired cerebellar degeneration?
long-standing alcohol abuse
What part of the cerebellum bears the brunt of the damage in alcoholic cerebellar degeneration?
the vermis, so you typically get progressive gait and truncal ataxia evolving over weeks to months
Postinfectious cerebellitis after varicella or other viral infection typically presents in kids ages 2-7. What is the prognosis?
good - the illness lasts a few weeks and recovery is usually complete
Paraneoplastic cerebellar degeneration typically causes a pancerebellar syndrome. What are the typical cancers for this process?
gynecological or small cell lung cancer
What are the two most common antibodies seen in paraneoplastic cerebellar degeneration?
anti-yo and anti-hu (but not specific)
How does Friedreich Ataxia usually present?
progressive ataxia affecting the arms more than legs with severe dysarthria - onset usually in childhood with loss of reflexes, spasticity, extensor plantar responses and impaired vibration and positional sense
The episodic ataxia syndromes are characterized by brief episodes of ataxia, vertigo, nausea, and vomiting. What is EA-1 a mutation of and what additional feature is associated in the interim between ataxia attacks?
mutations in a voltage gated potassium channel
interattack skeletal muscle myokymia
What is EA-2 a mutation of what and how does it differ clinically from EA-1?
mutation in the pore-forming alpha1 subunit of the PQ-type voltage gated calcium channel
ataxia attacks are longer, lasting several minutes, with interictal nystagmus
a progressive irreversible ataxia may develop late in the disease
When do the autosomal dominant spinocerebellar degenerations present?
typically in early adulthood with an insidious onset of progressive impairment of gait and dysarthria, often with cognitive decline as a late feature
Most of the defects identified in the SCAs are what?
CAG trinucleotide expansions
Which SCA is allelic to EA-2?
SCA6
What disorder is characterized by the triad of ataxia, areflexia and ophthalmoplegia?
Miller Fisher Syndrome
What is the ataxia due to in Miller Fisher Syndrome?
proprioceptive loss, not cerebellar dysfunction
What is the likely pathogenesis of Miller Fisher Syndrome?
It’s probably a variant of Guillain Barre - most likely mediated by a postinfectious immune process because IgG anti-GQ1b antibodies are detectable in the serum of over 90% of people with this syndrome
Describe a hemiparetic gait.
affected leg is stiff and does not flex at the hip, knee or ankle
the leg is circumducted, with a tendency to scrape the floor with the toes
arm is held in flexion and adduction and doe snot swing freely
Describe a spastic (paraparetic gait.
It’s basically a bilateral hemiparetic gait, so both legs have increased adductor tone with the legs tending to cross during walking (a scissoring gait)
Describe an akinetic-rigid gait.
posture is stooped with flexion of the shoulders, neck and trunk
gait is narrow-based, slow and shuffling with small steps and reduced arm swing. arms are carried flexed slightly ahead of the body. Often difficulty with gait initiation
Why do you see festination, propulsion (small steps forward) and retropulsion (small steps backward) in an akinetic-rigid gait?
the postural reflexes are impaired, so these movements are used in an effort to preserve equilibrium
What is the usual diagnosis for an akinetic-rigid gait?
idiopathic Parkinson disease, but can also be seen in other extrapyramidal disorders
How does the gait of progressive supranuclear palsy differ form that of PD?
the posture tends toward extension rather than flexion
Describe a frontal gait
posture if flexed with feet slightly apart.
gait initiation is impaired and the word “magnetic” is used to describe the patient’s difficulty in lifting the feet off the ground.
the patient advances with small, shuffling steps
with increasing severity, the patient may make abortive stepping movements in one place without being able to move forward
What is a waddling gait characteristic of?
hip girdle weakness
Describe a waddling gait
weakness of the abductors and consequent failure to stabilize the weight-bearing hip causes the pelvis and trunk to tilt toward the opposite side during walking
Where is the location of the lesion for a hemiparetic gait?
brainstem or cerebral hemisphere
Where is the lesion in a paraparetic gait?
spinal cord with demyelination, transverse myelitis or compressive myelopathy
or it could be bihemispheral in the cerebellum, but this is less likely
Describe the gait that occurs with sensory ataxia.
the patient can’t determin his/her position in space, so the gait becomes cautious
it is wide-based and steps are slow
contact with the ground is made with the hell and the forefoot strokes the floor with a slapping sound (slapping gait)
What’s the fancy term for a psychogenic gait?
astasia-abasia
yes, that’s seriously a term
What is the inheritance pattern for Freiderich’s ataxia/
autosomal recessive
Where does the FXN gene reside and what is the mutation?
chromosome 9
it’s an expanded GAA trinucleotide repeat (expanded to at least 66 units)
this severely reduces the amount of frataxin protein produced in cells
What are some associated symptoms of Freiderich’s Ataxia besides the neurological symptoms?
sensorineural hearing loss, diabetes mellitus and impaired glucose tolerance, hypertrophic cardiomyopathy and arrhythmias
