Flashcards in CN LANGE - Disorders Of Equilibrium I Deck (94):
Equilibrium depends on continuous ...?
3. Proprioceptive somatosensory input.
+ Integration in the brainstem and cerebellum.
Disorders of equilibrium result from diseases that affect:
1. Central or peripheral vestibular pathways.
2. The cerebellum.
3. Sensory pathways involved in proprioception.
Disorders of equilibrium - Usually present with one of two problems:
What is vertigo?
The ILLUSION of movement of the body OR the environment.
Vertigo may be associated with other symptoms, such as ...?
1. Impulsion (a sensation that the body is being hurled or pulled in space).
2. Oscillopsia = visual illusion of moving back and forth.
5. Gait ataxia.
Vertigo must be distinguished from ...?
NONvertiginous dizziness - Which includes sensations of:
NOT associated with an illusion of movement.
In contrast to vertigo, the non vertiginous dizziness is produced by conditions that ...?
Deprive the brain of:
--> May culminate in loss of consciousness.
The 1st step in the DDx of vertigo is to ...?
LOCALIZE the pathologic process to the PERIPHERAL or CENTRAL vestibular pathways.
Peripheral vs Central vertigo - Vertigo:
P --> Often intermittent, severe.
C --> Often constant, usually less severe.
Peripheral vs Central vertigo - Nystagmus:
P --> Always present, unidirectional, never vertical.
C --> May be absent, uni- or bidirectional, may be vertical.
Peripheral vs Central vertigo - Hearing loss or tinnitus:
P --> Often present.
C --> Rarely present.
Peripheral vs Central vertigo - Intrinsic brainstem or cerebellar signs:
P --> Absent.
C --> Typically present.
Peripheral vertigo - Definition:
Peripheral vestibular lesions =
1. Affect the labyrinth of the inner ear.
2. Affect the vestibular division of the vestibulocochlear (VIII) nerve.
Central vertigo - Definition:
Vertigo of CNS origin:
1. Lesions of brainstem vestibular nuclei or their connections.
2. Symptom of complex partial seizures by a cerebral cortical lesion (rare).
Central vertigo - Nystagmus may differ in character ...?
In the 2 eyes.
Central vertigo may be accompanied by intrinsic brainstem or cerebellar signs, such as:
1. Motor or sensory deficits.
3. Extensor plantar respones.
5. Limb ataxia.
Ataxia - Definition:
Incoordination OR clumsiness of movement that is NOT the result of muscle weakness.
Ataxia - 3 etiologies:
3. Sensory (proprioceptive) disorders.
Ataxia can affect ...?
1. Eye movement.
2. Speech (producing dysarthria).
3. Individual limbs.
4. The trunk.
5. Stance or gait.
Vestibular ataxia - Etiology:
The same CENTRAL/PERIPHERAL lesions that cause PERIPHERAL/CENTRAL vertigo can also produce vestibular ataxia.
Vestibular ataxia - Nystagmus:
Frequently present and is typically UNILATERAL and most pronounced on gaze AWAY from the side of vestibular involvement.
Vestibular ataxia - Any dysarthria?
Vestibular ataxia is ...?
GRAVITY-DEPENDENT = Incoordination of the limbs becomes apparent only when the patient attempts to stand or walk.
Cerebellar ataxia - Definition:
1. Lesion of the cerebellum.
2. Its afferent/efferent connections in the cerebellar peduncles, red nucleus, pons, or spinal cord.
What can occasionally mimic disorder of a cerebellar hemisphere?
UNILATERAL FRONTAL DISEASE --> CONTRALATERAL cerebellar hemisphere.
--> Because of the crossed connection between the frontal cerebral cortex and the cerebellum.
Cerebellar ataxia - The clinical manifestations consist of irregularities in the:
of VOLUNTARY movements.
Cerebellar ataxia - Hypotonia:
Reduced muscle tone --> Defective posture maintenance.
--> Limbs are easily displaced by a relatively small force - When shaken by the examiner exhibit an INCREASED RANGE of excursion.
Cerebellar ataxia - Range of arm swing?
Similarly increased (hypotonia).
Cerebellar ataxia - Tendon reflexes take on a ...?
PENDULAR QUALITY, so that several oscillations of the limb may occur after the reflex is elicited.
Cerebellar ataxia - Rebound movement of the limb:
When muscles are contracted against resistance that is then removed, the antagonist muscle fails to CHECK the movement and compensatory muscular relaxation does NOT occur promptly --> REBOUND MOVEMENT OF THE LIMB.
Cerebellar ataxia - In addition to hypotonia, cerebellar ataxia is associated with ...?
INCOORDINATION of VOLUNTARY movements.
Cerebellar ataxia - What does incoordination of movements mean?
1. Simple movements are delayed in onset.
2. Decreased rates of acceleration/deceleration.
3. Rate + Rhythm + Amplitude + Force (RRAF) of movements FLUCTUATE --> Jerky appearance.
Cerebellar ataxia - Clinical manifestations:
1. Terminal dysmetria ("overshoot") when the limb is directed at a target.
2. Intention tremor as the limb approaches the target.
3. ASYNERGIA = More complex movements may be decomposed into a SUCCESSION of individual movements rather than a single smooth motor act.
--> Movements that involve rapid changes in direction or greater physiologic complexity, such as walking, are most severely affected.
Cerebellar ataxia - Eye movement abnormalities:
Because of the cerebellum prominent role in the control of eye movements --> OCULAR ABNORMALITIES = Frequent consequence.
1. Nystagmus + related ocular oscillations.
2. Gaze paresis.
3. Defective saccadic and pursuit movements.
Cerebellar ataxia - Anatomic basis of clinical signs - Midline lesions:
Vermis + Flocculonodular lobe + Associated subcortical (fastigial) nuclei --> Control of AXIAL FUNCTIONS:
1. Eye movements.
2. Head and trunk posture.
Cerebellar ataxia - Midline cerebellar disease results in a clinical syndrome characterized by ...?
1. Nystagmus + Other disorders of ocular motility.
3. Titubation = Oscillation of the head and trunk.
4. Instability of stance.
5. Gait ataxia.
Cerebellar ataxia - Midline lesions - Selective involvement of the superior cerebellar vermis, as in ...?
ALCOHOLIC cerebellar degeneration --> produces primarily GAIT ATAXIA (as predicted by the somatotopic map of the cerebellum).
The cerebellar hemispheres - Role:
1. Help maintain tone in the ipsilateral limbs.
2. Also regulate ipsilateral gaze.
Disorders affecting one cerebellar hemisphere cause ...?
1. IPSILATERAL hemiataxia + limb hypotonia.
2. Nystagmus and transient IPSILATERAL gaze paresis (inability to look voluntarily TOWARD the affected side).
Involvement of the medial (paravermian) portion of either cerebellar hemisphere can also produce ...?
Cerebellar ataxia - Diffuse disease:
Toxic, metabolic, and degenerative conditions affect the cerebellum diffusely.
--> The clinical picture combines the features of midline + bilateral hemisphere disease.
Cerebellar connections in the SUPERIOR cerebellar peduncle - Afferents/Efferents:
Afferent: Ventral spinocerebellar.
Efferent: Cerebellorubral, cerebellothalamic, cerebelloreticular.
Cerebellar connections in the MIDDLE cerebellar peduncle:
Cerebellar connections in the INFERIOR cerebellar peduncle:
Afferents: Vestibulo, cuneo, nucleo, reticulo, olivo, arcuato- CEREBELLAR + Dorsal spinocerebellar.
Sensory ataxia - Definition:
Results from disorders that affect the PROPRIOCEPTIVE pathways in:
1. Peripheral sensory nerves.
2. Sensory roots.
3. Posterior columns.
4. Medial lemnisci.
2 rare causes of CONTRALATERAL sensory hemiataxia:
1. Thalamic lesions.
2. Parietal lobe lesions.
Sensation of joint position and movement (kinesthesis) originate in ...?
Pacinian corpuscles + unencapsulated nerve endings in joint capsules, ligaments, muscle, and periosteum.
The sensations of joint position and movement (kinesthesis) are transmitted via ...?
Heavily myelinated A fibers of primary afferent neurons, which enter the dorsal horn of the spinal cord and ascend uncrossed in the posterior columns.
Sensory ataxia from polyneuropathy or posterior column lesions typically affects the ...?
GAIT + LEGS in symmetric fashion.
--> Arms are involved to a LESSER EXTENT or spared entirely.
Sensory ataxia - Examination reveals ...?
1. Impaired sensation of joint position in the affected limbs.
2. Vibration sense is also commonly disturbed.
3. Vertigo, nystagmus, dysarthria = ABSENT.
Clinical patterns of cerebellar ataxia - 4 locations:
1. Midline = Nystagmus, dysarthria, head and trunk titubation, gait ataxia.
2. Superior vermis = Gait ataxia.
3. Cerebellar hemisphere = Nystagmus, ipsilateral gaze paresis, dysarthria, ipsilateral hypotonia, ipsilateral limb ataxia, gait ataxia, falling to side of lesion.
4. Diffuse (Pancerebellar) = Nystagmus, bilateral gaze paresis, dysarthria, bilateral hypotonia, bilateral limb ataxia, gait ataxia.
Cerebellar ataxia - Midline involvement - Causes:
Cerebellar ataxia - Superior vermis lesions - Causes:
1. Wernicke encephalopathy.
2. Alcoholic cerebellar degeneration.
Cerebellar ataxia - Cerebellar hemisphere lesions - Causes:
Cerebellar ataxia - Pancerebellar (diffuse) involvement - Causes:
1. Sedative drug intoxication.
3. AD spinocerebellar ataxias.
4. Paraneoplastic cerebellar degeneration.
6. Infectious/Parainfectious encephalomyelitis.
What is equilibrium?
The ability to maintain orientation of the body and its parts in relation to external space.
History - Symptoms and signs - True vertigo must be distinguished from ...?
A light-headed or a presyncopal sensation.
History - Vertigo is typically described as spinning, rotating or moving, but when the description is vague, the patient should be asked ...?
If the symptom is associated with a SENSE OF MOVEMENT.
The circumstances under which symptoms occur may also be diagnostically helpful:
Vertigo = Brought on by changes in head position.
Orthostatic hypotension = Symptoms upon arising after prolonged recumbency.
Symptoms associated with vertigo may help to localize the site of the causal lesion:
1. Hearing loss or tinnitus --> Peripheral vestibular apparatus (labyrinth or VIII nerve).
2. Dysarthria, dysphagia, diplopia, or focal weakness or sensory loss affecting the face or limbs points to a likely central (brainstem) lesion.
Ataxia associated with vertigo suggests ...?
A vestibular disorder.
Ataxia associated with numbness or tingling in the legs is common in patients with ...?
Patients with sensory ataxia may be less steady in ...?
In the DARK + Mor difficulty in DESCENDING than ascending stairs.
History - Onset and time course - SUDDEN onset of disequilibrium occurs with ...?
Infarcts/hemorrhages in the brainstem/cerebellum --> Lateral medullary syndrome, cerebellar hemorrhage/infarction.
EPISODIC disequilibrium of acute onset suggests:
1. TIAs in the basilar artery distribution.
2. Benign positional vertigo.
3. Meniere disease.
4. Vestibular migraine.
Disequilibrium from TIA is usually accompanied by ...?
1. Cranial nerve deficits.
2. Neurologic signs in the limbs.
CHRONIC/PROGRESSIVE disequilibrium is most suggestive of ...?
1. Toxic or nutritional disorder (eg B12 or vitE def./ NO exposure).
2. Inherited spinocerebellar degeneration (if evolution over months-years).
The medical history should be scrutinized for diseases that affect the sensory pathways or cerebellum:
B12 + Syphilis --> Sensory pathways.
Hypothyroidism + Paraneo + Tumors --> Cerebellum.
The medical history should be scrutinized for drugs that impair vestibular or cerebellar function:
2. Sedative drugs.
The family history - A hereditary degenerative disorder may be the cause of chronic, progressive cerebellar ataxia:
1. Spinocerebellar degeneration.
2. Friedreich ataxia.
General physical examination - Clues to the underlying disorder - Orthostatic hypotension:
1. Tabes dorsalis.
3. Spinocerebellar degeneration.
General physical examination - Clues to the underlying disorder - Skin:
1. Oculocutaneous telangiectasia (ataxia-telangiectasia).
2. Dry, brittle hair (hypothyroidism).
3. Lemon-yellow coloration (B12 def.).
General physical examination - Clues to the underlying disorder - Pigmented corneal (Kayser-Fleisher rings):
General physical examination - Clues to the underlying disorder - Skeletal abnormalities:
1. Kyphoscoliosis (Friedreich ataxia).
2. Hypertrophic or hyperextensible joints in tabes dorsalis.
3. Pes cavus in certain neuropathies.
4. Abnormalities at the craniocervical junction may be associated with Arnold-Chiari malformation or other congenital disorders involving the posterior fossa.
Neurologic exam - Mental status exam - Acute confusional state + ataxia suggests:
1. Ethanol or sedative drug intoxication.
2. Wernicke encephalopathy.
Neurologic exam - Mental status exam - Dementia with cerebellar ataxia:
5. Spinocerebellar degenerations.
Neurologic exam - Mental status exam - Dementia + sensory ataxia suggests:
1. Syphilitic taboparesis.
Mental status exam - Amnesia + cerebellar ataxia:
Chronic alcoholism (Korsakoff syndrome).
Stance and gait - Observation of the stance and gait is helpful in distinguishing among vestibular, cerebellar, and sensory ataxia. In ANY ataxic patient, the stance and gait are ...?
1. Wide-based + unsteady.
2. Reeling or lurching movements.
Patients with vestibular ataxia tend to fall ... the side of the lesion in Romberg.
The gait in cerebellar ataxia is ...?
Wide-based, often with staggering quality that can suggest drunkenness.
--> Oscillation of the head or trunk (titubation) may be present.
Cerebellar ataxia - Gait - With unilateral cerebellar hemisphere lesion, there is a tendency to deviate ...?
TOWARDS the side of the lesion, when the patient tries to walk in a straight line or circle, or marches in place with eyes closed.
Cerebellar ataxia - Gait - Tandem gait:
Sensory ataxia - The gait is also ...?
WIDE-based + Tandem gait is poor.
--> Feet are lifted high off the ground and slapped down heavily (steppage gait) to enhance proprioceptive input.
In sensory ataxia - Stability may be dramatically improved by ...?
Letting the patient use a cane or lightly rest a hand on the examiner's arm for support.
Gait ataxia may also be a manifestation of ...?
Conversion disorder or malingering.
Conversion disorder or malingering - The most helpful observation in identifying factitious gait ataxia is that ...?
Such patients may exhibit wildly reeling or lurching movements from which they are able to recover without falling.
Cranial nerve exam:
Abnormalities of extraocular (III, IV, VI) and VIII nerve function typically presents with vestibular disease and often present with lesions of the CEREBELLUM.
Nystagmus - an involuntary oscillation of the eyes - is characterized in terms of ...?
1. The position of gaze in which it occurs (gaze-evoked nystagmus).
2. Its amplitude.
3. Direction of the fast phase.
Pendular nystagmus usually due to visual impairment beginning in ...?
INFANCY - Same velocity in BOTH directions.
Jerk nystagmus has ...?
Fast (vestibular-induced) + slow (cortical) phases.
The direction of jerk nystagmus is defined by the direction of the fast component.
Peripheral vestibular disorders produce what jerk nystagmus?
UNIDIRECTIONAL + HORIZONTAL that is maximal on gaze AWAY from the involved side.
Central vestibular disorders - Nystagmus;
1. UNI- or BIDIRECTIONAL.
2. HORIZONTAL or VERTICAL.
3. Gaze paresis.