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Cerebellar Disorders

Terms in this set (19)

Deficits of the cerebellum are ipsi/contra?

Acute lesions accompanied by nausea/vomiting due to _____?
ipsilateral due to double crossing

vertigo
Cerebellar inputs: what is the pathway?

Motor

Visual, sensory, motor

Proprioceptive
Motor: information from spinal cord -> Ventral spinocerebellar tract -> sup. cerebral peduncle -> cerebellum

Visual, sensory, motor: information from cortex -> pontine nuclei -> middle cerebral peduncle -> cerebellum

Proprioceptive: information from limbs -> fasciculus gracilis/cuneatus -> dorsal spinocerebellar tract & cuneocerebellar tract -> inferior cerebral peduncle -> cerebellum
Cerebellar outputs: what is the pathway?

For movement

head/eye control & posture

unconscious motor control (muscle tone)
For movement: cerebellum -> VL thalamus -> primary motor & supplementary motor cortex -> ventral & lateral corticospinal tract -> movement

head/eye control & posture: cerebellum -> vestibular nuclei -> head/eye control & posture

unconscious motor control: cerebellum -> medullary & pontine reticular formation -> medullary & pontine reticulospinal tract -> unconscious motor control
Ataxia can be caused by ipsilateral cerebellar lesions. 2 types.

Cause of trunkal ataxia

Cause of appendicular ataxia

Appropriate tests? Positive signs?
uncoordinated muscle movements = problems with speed, range, force, timing

Vermian lesion = trunkal ataxia = walk like drunk, Romberg test (stand straight feet together and close eyes)

Cerebellar hemisphere lesion (lesion of ipsilateral lateral hemispheres = Appendicular ataxia = difficulty coordinating an extremity. Manifests as dysmetria / dysrhythmia

Dysmetria = over/undershoot of a limb during movement TOWARD a target = (unable to complete finger-nose-finger, heel to shin),

Dysrhythmia = abnormal rhythm and timing of a movement = (can't do finger tap test),

Dysdiadochokinesia = abnormal speed/rhythm when tapping hand with palm / dorsum alternatively = (can't do hand flip test)
Tremor: 3 types

Definition

Types:

Location of lesion causing each type
Tremor = involuntary, rhythmic oscillation of a body part

Postural tremor = tremor occurring when a limb is held in a particular position = lesion of ipsilateral lateral hemispheres = check for tandem gate (be able to walk one foot after the other)

Action/intentional tremor = tremor that occurs when limb is in motion = lesion of ipsilateral lateral hemisphere

Titubation (yes or no "shake) = tremor of trunk or head = lesion of vermis
Essential tremor = shake in head/voice
Ocular dysmetria:

Definition

Cause

Types of eye movements
overshoot (hypermetric saccades) or undershoot of eyes when patient focuses on target

lesion = flocculonodular lobe lesion (part of lateral hemispheres)

Eye movements: flocculonodular lobe

Saccades = quick, voluntary movement of eyes onto target, mediated by cortex - frontal & parietal eye fields

Slow eye movements = involuntary movement of eyes mediated by cerebellum, vestibular nuclei & pathways, and extraocular motor nuclei
Nystagmus

Definition

Cause

Lesion

Types

Examples:
rhythmic oscillation of the eye, mediated by the cortex

Slow phase

Fast phase = named after this phase = example "right beating nystagmus" means that the fast phase is to the right and slow phase is to the left

Cause: deficit of the "slow eye movement" system

Lesion: flocculonodular lobe

Types: Horizontal, vertical, or rotary nystagmus
-PURELY Vertical = look up and beats up or look down or beats down = ALWAYS a CNS lesion (brainstem or cerebellar injury) like stroke or hemorrhage

-Direction-changing nystagmus is CENTRAL = the nystagmus beats in EVERY direction that patient looks = two separate lesions on both sides of CNS

-Horizontal/rotary = CENTRAL or PERIPHERAL nervous system lesion = nystagmus that ONLY beats in ONE direction

Examples:
R beating horizontal nystagmus on R gaze, upgaze, downgaze
Clinical: Slow saccades

Definition

Where is lesion?

Mechanism of action

Scanning (ataxic) speech

Hypotonia of ipsilateral limb
Slow saccades = slowness in eye movements when trying to QUICKLY look at target

Lesion: flocculonodular region (cerebellum) = problem with VOR suppression

MOA:---> VOR is designed to move eyes to OPPOSITE side of head movement. If you wanted eyes to move to the SAME side of head movement you must suppress VOR. Ex. If head moves L and you want eyes to move L then you must suppress L VOR. This is done by L cerebellum.
Clinical: Hypotonia of ipsilateral limb

Cause:

Where is lesion?
Lesion: Ipsilateral cerebellar lesion = they fall towards side of lesion

Cause: b/c cerebellum influences corticospinal tracts
Clinical: Scanning (ataxic) speech

Where is lesion?
slow effortful speech with difficulty articulating

Lesion: lateral hemispheres (cerebellar)
Differential diagnoses of cerebellar dysfunction:

3 types of dysfunction

Presence of dysmetria/ataxia on finger to nose or heel to shin

How do we clinically deduce cerebellar disorders? What are some causes of each method?
vestibular dysfunction = vertigo, difficulty walking, nystagmus, nausea and vomiting
NO dysmetria or ataxia on finger to nose or heel to shin

Corticospinal tract dysfunction = IPSILATERAL hypotonia & weakness often MISTAKEN for ataxia

Impaired proprioception = patients have a sensory ataxia = nerves in feet are dying off = (proprioceptive loss in feet makes walking difficult)

Example of lesion localization: right dysmetria on finger to nose means that it is a right cerebellar lesion

Clinical deduction for cerebellar disorders:
-determine if the process is ACUTE or CHRONIC
-localize the lesion

Acute causes: stroke, alcohol intoxication, drug overdose, multiple sclerosis

Chronic causes: essential tremor, spinocerebellar ataxia, tumor (astrocytoma), chronic alcoholism
Case:
70 y/o man w HTN developed acute onset nausea vomiting and unsteadiness. Exam shows dysarthria, dysmentria on R FTN & HTS testing and R dysdiadochokineseia. Upon standing, fell to R.

Localize symptoms/signs and give most likely diagnosis.

Pathogenesis?
Case: Cerebellar stroke

Symptoms are acute in onset = ischemic / hemorrhagic

Localize: Nausea and vomiting & unsteadiness -> could be vestibular or cerebellar

Dysarthria = corticobulbar, vestibular, cerebellar, CN X, XII, or their nuclei

Dysmetria on R & dysdiadochokinesia = R cerebellar hemisphere lesion

Falling to the R = R cerebellar hemisphere lesion

Diagnosis: bc symptoms are acute we suspect R cerebellar stroke (lateral & flocconodular lobes) and vermian lesion due to the stroke

Test: MRI of brain bc it will show R cerebellar stroke

Pathogenesis: a cerebellar stroke can happen in any of the cerebellar arteries: PICA, AICA, or SCA
Strokes:

Types: 2

Mechanisms: 2
Strokes:

Types:
1) ischemic = deprivation of blood

2) hemorrhagic = ruptured vessel

Mechanisms:
1) medium sized arteries (PICA, SCA, AICA) = atherosclerosis = diseased vessels due to occlusion

2) small arteries = arteriosclerosis = thickening of the vessels
Case:

45 y/o housewife falls in shower while washing hair 1 week ago. Husband notices she's clumsier than usual with unsteadiness of gait over the past year.

Exam shows dysmetria bilateral, inability to tandem, and + Romberg signs

Is it acute or chronic?

Localize

Cause?
Case: Alcoholism

Chronic because husband noticed over past year.

Localize:
1) falling in shower (like a Romberg test) because the patient closes eyes while washing hair -> VERMIS

** at this point, + Romberg means nothing because it could be vestibular, cerebellar, or proprioception of feet induced **

2) Dysmetria bilateral -> bilateral cerebellar hemispheres

3) Inability to tandem -> VERMIS or proprioceptive loss

Localize: chronic lesion of cerebellar vermis & cerebellar hemispheres

Diagnosis / Cause: Alcoholism = chronic alcohol leads to degeneration of vermis and cerebellar hemispheres. Tumor could also cause this.

MRI of brain should show atrophy of cerebellar vermis >> cerebellar hemispheres >> degeneration of folia, purkinje cells, and vermis
Case:

45 yo male presents with slowly progressive unsteadiness of hands / shaking of head. Worsens when working with hands. Father / sister have similar condition.

Acute or chronic?

Localize

Cause?

Diagnosis
Case: Essential tremor

Lesion is chronic

Because it worsens when he uses his hands then its indicative of INTENTION tremor & bilateral

Because it is bilateral then it must be ESSENTIAL tremor

Essential tremor is AUTOSOMAL DOMINANT

Cause: neurodegenerative = gradual loss of Purkinje cells

Localize: cerebellar hemispheres & vermis
Case:

13 yo boy has 2 mo history of AM headaches, nausea, slurred speech, unsteadiness. During past week, had difficulty concentrating at school, difficulty writing with RIGHT hand, and blurred vision.

Exam shows papilledema (increased intracranial pressure causing swelling of ocular nerves), horizontal & vertical nystagmus, R hand dysmetria on FTN, + Romberg, wide-based unsteady gait.

Acute or chronic?

Localize

Cause?

Diagnosis
Case: Astrocytoma = most common brain tumor in children

Chronic due to 2 mo history

Localize:
1) Right hand dysmetria = R cerebellar hemisphere
2) Unsteadiness/wide-based gait/+Romberg -> vermis
3) Vertical Nystagmus -> CNS -> cerebellum & vestibular nuclei
4) Papilledema/HA/nausea&vomiting/concentration difficulty -> caused by the increased intracranial pressure (ICP)

Cause: slow growing lesion that is effecting the ipsilateral / Right cerebellum & increasing ICP = either a tumor or mass lesion

Diagnosis: R cerebellar tumor which IN THIS AGE POPULATION is most likely an ASTROCYTOMA
Case:

35 yo female has slowly progressive difficulty walking, shaking of arms when doing tasks, slowing and slurrying of speech since age 20. 2/4 siblings affected. Mother died at 60 of similar disease to aspiration pneumonia.

Exam shows dysmetria bilateral, truncal ataxia, slowed saccades, end-gaze nystagmus.

Acute or chronic?

Localize

Cause?

Diagnosis
Case: Spinocerebellar ataxia = slowed degeneration of the nerves

Chronic

Localize:
1) Dysmetria bilateral -> bilateral cerebellar hemispheres
2) Truncal ataxia -> vermis
3) Nystagmus / slowed saccades -> flocculonodular lobe

Cause: autosomal dominant - CAG repeats (triplet expansion) - > neurodegeneration of purkinje cells which affects ALL portions of cerebellum and patients die due to difficulty swallowing.

Diagnosis: Spinocerebellar ataxia
Case:

Symptoms: sudden onset vertigo, N/V, falling to the right. R dysmetria on FTN & HTS. R beating nystagmus on R gaze. L beating horizontal nystagmus on L gaze, vertical nystagmus on upgaze.

Acute or chronic

Localize

Diagnosis

Regions under attack:
Case: Multiple Sclerosis

Acute

Localize:
1) N/V, falls to R & R dysmetria = R cerebellar hemisphere
2) Direction changing nystagmus / vertical nystagmus = CENTRAL = cerebellum

Diagnosis: Multiple sclerosis = autoimmune/inflammatory disorder affecting CNS white matter.

Regions under attack:
1) cerebellar white matter (middle cerebellar peduncle)
2) medial longitudinal fasciculus = white matter tract that mediates eye movements
3) spinal cord = can result in complete or incomplete cord lesion
Pt suffered stroke of cerebellum. Exam shows:

Right FTN dysmetria
Right HTS dysmetria
Inability to suppress VOR when trying to follow object crossing in front of him from R to L.

Localize each symptom.

What was damaged by the stroke?
Pt suffered stroke of cerebellum. Exam shows:

Right FTN dysmetria = Right cerebellar hemisphere

Right HTS dysmetria = Right cerebellar hemisphere

Inability to suppress VOR when trying to follow object crossing in front of him from R to L = LEFT Vermis because this is the one that needs to be suppressed.

What was damaged by the stroke?
--> RIGHT lateral cerebellar hemisphere and LEFT vermis
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