| EM guidemap - Ataxia, incoordination and dysequilibrium |
Click on any of the headings or subheadings to rapidly navigate to the relevant section of the guidemap
Definitions and general principles
- ataxia
- dyssynergia
- dysmetria
- dysdiadochokinesis
- hypotonia
- nystagmus
- dysarthria
- tremor and titubation
- Romberg's test
- posterior circulation stroke syndromes
- cerebellar damage in chronic alcoholism
- causes of sensory ataxia
| Introduction |
- this guidemap is mainly focused on problems of ataxia and incoordination due to cerebellar disease, and it offers an emergency physician basic guidance on how to problem-solve clinical cases of ataxia and incoordination using elementary clinical knowledge and selective diagnostic testing
- dysequilibrium is a loss of balance without an abnormal sensation in the head, occurring only when the patient is standing or walking; it disappears upon sitting down, and is often caused by disorders of the motor system
- when a patient presents to an ED with vague symptoms of incoordination,
dysequilibrium and/or an inability to walk, it is imperative that an emergency
physician perform a thorough clinical evaluation of the cerebellar system,
so that he can optimize his chances of successfully problem-solving the
clinical problem
| Definitions and general principles |
- some common symptoms of cerebellar disease include:-
- headache
- nausea and vomiting
- gait unsteadiness
- dizziness or postural insecurity
- double vision
- blurred vision
- limb clumsiness
- limb weakness (hypotonia)
- kinetic or postural tremor
- dysarthria
- signs of cerebellar disease include:-
- gait ataxia
- disturbed stance
- limb dysmetria
- limb dysynergia
- kinetic (intention) tremors
- dysarthria
- past-pointing
- excessive rebound
- impaired check
- dysdiadochokinesis
- head tilt or titubation
- hypotonia
- nystagmus
- ocular dysmetria or ocular dysynergia
- gaze palsies
Ataxia is fundamentally a disturbance of muscle incoordination, which is not the result of muscle weakness or loss of muscle tone, or the intrusion of abnormal muscle movements
- implicit in the definition of ataxia is the presumption that muscle strength is not impaired, or not sufficiently impaired, to cause muscle incoordination
- the ataxic patient has problems with the accuracy and organization of voluntary muscle actions, resulting in uncoordinated movements involving the trunk and/or limbs and/or speech and/or eye movements
- the incoordination consists of irregularities in the rhythm, rate, and amplitude of voluntary movements => voluntary movements become jerky and erratic
- cerebellar gait disturbances involve disturbances in stance and gait => see the gait disorders, drop attacks and frequent falls guidemap for further details
- ataxia may primarily involve the trunk (truncal ataxia) and the patient may not be able to sit or stand unsupported (astasia); truncal ataxia is usually due to midline cerebellar disease, and associated limb ataxia due to lateral cerebellar hemisphere disease may not be present
- incooordination of walking (gait ataxia) that is so severe that the patient cannot walk is called abasia, and the term astasia-abasia is used if the the patient's balance is so impaired that the patient cannot maintain his balance when either sitting or walking
- persistent incoordination of the truncal axial musculature may produce body tilts, pelvic tilts or head tilts
- severe lower limb dysmetria and dysynergia (due to lateral cerebellar hemisphere disease) may rarely produce an inability to walk, and mimic cerebellar gait ataxia (due to midline cerebellar disease)
Dysynergia is an inability to smoothly perform the elements of a movement in the appropriate space and the correct time, and errors in the speed and sequence of the component parts of a movement causes a breakdown of a multi-joint movement into its constituent parts
- a patient with dysynergia cannot complete a smooth motor act, and the motor act decomposes into a series of fragmented individual movements so that smooth movements becomes erratic and irregular
- dysynergia can also involve eye movements, so that smooth pursuit eye movements, which normally occur when the eyes track a slowly moving object moving across the field of vision, become disrupted and fragmented
- ocular dysynergia is best tested by asking the patient to follow the slow movement of a visual target across the visual field (eg. physician's finger held 18 - 36" in front of the patient's face and slowly and smoothly moved from one side to the other side, and up and down) => a failure of either eye to move promptly, or smoothly - "broken-up" or "catch-up" stepped pursuit eye movements - suggests ocular dysynergia
(* the examiner's finger must not move too fast because smooth pursuit performance decays with age, inattention, and use of alcohol or certain drugs)
- bidirectionally stepped smooth pursuit defects can suggest diffuse brain disease or drug intoxication (because both the cerebral cortex and cerebellum are involved in pursuit eye movements), while unidirectionally stepped pursuit defects suggests brainstem-cerebellar disease
- in brainstem-cerebellar disease the pursuit steps tend to be frequent so that the overall envelope of pursuit closely approximates the trajectory of the slowly moving visual target => only slight oscillation of the eye might be visible during smooth pursuit testing, while cerebral cortex lesions cause pursuit step defects that are large and poorly controlled and easily recognized
Limb dysmetria is an inability to place and position a limb correctly, in both range and direction, across the plane of more than one joint
- a dysmetric limb mainly has difficulties with the initiation and termination of limb movements, and a limb with terminal dysmetria often moves beyond the target (hypermetria), or fails to reach the target (hypometria) during a voluntary movement; hypermetria is more suggestive of cerebellar disease than hypometria
- past-pointing refers to terminal limb dysmetria, and can be seen during finger-nose testing with the upper arm abducted to 90 degrees => elbow movement is tested by asking the patient to sequentially touch his nose and then touch a target held about 18 - 36" directly in front of his face => upper limb hypermetria will cause the patient's finger to strike his face because the patient cannot control the amplitude of the elbow movement
- another test of past-pointing is Barany's pointing test => the patient is asked to hold both arms extended horizontally in front => the examiner's finger touches the patient's extended forefinger => the patient is instructed to move the arm downward and then upward again to exactly reach the examiner's finger => after a few practice trials with preserved vision, the patient is asked to repeat the procedure with eyes closed => failure to control the limb causing past-pointing suggests terminal dysmetria
- a limb with severe dysmetria may oscillate widely as corrective movements are made during the limb movement to correct for errors made during the original limb trajectory => the large oscillations may suggest a severe intention tremor, which is also commonly present in cerebellar disease
- lower limb dysmetria is tested by heel-knee testing in the supine position => the one leg is elevated and the heel is placed on the opposite knee => the heel is then run smoothly down the leg to the top of the foot
- severe leg dysmetria will cause the heel to overshoot and miss the knee, and/or oscillate widely as it runs down the leg to finally overshoot the foot in an uncontrolled manner
(* poor performance of the heel-knee test is not necessarily a sign of cerebellar disease, because it is a difficult test to perform - especially for frail elderly patients)
- limb dysmetria is usually due to disease of the cerebellar hemispheres and the most common pattern is for limb dysmetria to be present ipsilateral to the side of the cerebellar hemisphere lesion, but it can also be contralateral to the lesion => localization is not completely reliable
- with diffuse or degenerative cerebellar disease, the dysmetria is bilateral with little right-left asymmetry
The failure to demonstrate abnormalities of cooordination when the patient is lying in bed should never be considered as excluding cerebellar disease, because gross gait ataxia - due to midline cerebellar disease or cerbellar tonsillar herniation - may still be present
- dysmetria can also involve the extraocular eye muscles, and voluntary rapid eye movements towards a fixed target in space can either overshoot the target (hypermetric saccade) or undershoot the target (hypometric saccade)
(* saccades are rapid eye movements by which we voluntarily shift the line of sight between objects of interest)
- ocular dysmetria is tested by asking the patient to suddenly look at a fixed object in space, and observing for symmetry of the rapid voluntary eye movements (saccades) => a dysmetric eye may overshoot the visual target (hypermetria) and then show a short series of corrective step-saccades back towards the target, or the dysmetric eye may undershoot the visual target (hypometria) and have to undergo a short series of additional "catch-up" step-saccades to fixate on the target
(* with ocular dysmetria, the eyes appear to transiently oscillate about the visual target with movements of progressively smaller amplitude as fixation is established; opsoclonus - also called saccodomania- refers to to a disturbance of conjugate gaze in which the eyes manifest frequent involuntary rapid saccadic movements of varying amplitude and direction and the "dancing eyes" of saccodomania, which can persist during sleep, suggest diffuse cerebellar disease eg. paraneoplastic cerebellar degeneration; ocular flutter refers to paroxysmal side-to-side movements of the eyes that can often accompany ocular dysmetria in patients with cerebellar disease)
- the most distinctive type of cerebellar ocular dysmetria involves saccadic overshoot, and is best seen when the patient returns his eye position to primary forward gaze after conjugate gaze deviation => the eye temporarily oscillates as the patient attempts to re-fixate his vision on a visual target directly ahead
- hypermetric saccades are near-pathognomonic for lesions of the midline cerebellum (fastigial nuclei and dorsal vermis), while hypometric saccades can also be found in other (non-cerebellar) posterior fossa disorders
- formal saccadic testing is best done by sitting opposite the patient and then i) verbally instructing the patient to look to the left and then to the right (observing for dysfunction of on command saccades); ii) asking the patient to look at visual targets (examiner's fingers held alongside the examiner's head) in a self-paced manner (observing for dysfunction of self-paced saccades), and iii) asking the patient to only look at the finger which is actively moving at any moment (observing for visually elicited saccades)
- patients with basal ganglia or frontal lobe disorders may show difficulty in initiating saccades in response to a verbal command or when self-paced, but saccades to suddenly appearing visual targets (eg. flickering of the examiner's fingers during testing of visually elicited saccades) can be normal
- patients with cerebellar disease have abnormal saccades in response to all testing modalities (although the degree of abnormality may vary according to the modality of testing)
(* terminal ocular dysmetria causes jerky eye movements only at the end of a rapid voluntary eye saccade; by contrast, ocular dysynergia produces jerky eye movements continuously during a slow, smooth eye pursuit movement)
Dysdiadochokinesis refers to the fragmentation of rapid alternating muscle movements seen in cerebellar disease
- dysrhymokinesis refers to a disrupted rhythm of fine motor movements eg. finger or foot tapping
- dysdiadochokinesis is best tested by asking the patient to slap his thigh with the palm of his hand and then flipping the hand over to slap the thigh with the back of his hand, while the examiner listens for the regular smoothness of repetitive discrete slaps of the hand against the thigh and also observes the smoothness and rhythm of the repetitive wrist movements
- dysrhythmokinesis is best tested by asking the patient to attempt to play an imaginary piano in the air in front of his body and assessing the speed, smoothness, and regularity of rapid finger movements; or by asking the patient to tap his fingertips rapidly and smooothly against a tabletop while resting his palm on the table
- dysdiadochokinesis and dysrhythmokinesis - like limb dysmetria - is usually seen in diseases of the cerebellar hemisphere, and is usually ipsilateral to the side of the pathology
- acute cerebellar hemisphere disease often produces diffuse hypotonia, which results in defective maintenance of posture; the hypotonia disappears in a few days or weeks
- unilateral hemisphere disease may produce ipsilateral limb hypotonia
- hypotonia may be detected by noting that the limbs can easily be displaced with little force, and that arm excursion during walking is increased
- patellar tendon reflexes become pendular, and the limb oscillates for a number of oscillations before stopping
- changes in mucle tone are usually associated with impaired check and rebound, and these signs are elicited by having the patient extend the arms directly forward and keep them in one plane as the examiner taps the wrist with enough force to move the wrist slightly => exaggerated movements of the arm +/- slight oscillations suggest an impaired check and rebound phenomenon
(* another indication of impaired check is the inability to stop a strenuous contraction of a limb muscle eg. the examiner asks the patient to keep his arm flexed while the examiner attempts to straighten the arm while holding onto the wrist => the flexed forearm will strike the upper arm in an uncontrolled manner when the examiner suddenly releases the actively flexed forearm without warning)
- the nystagmus in cerebellar disease can consist of many different types and be difficult to classify
- gaze-evoked nystagmus is the most common type of cerebellar nystagmus
- in gaze-evoked nystagmus the patient develops jerking eye movements on conjugate gaze to the side or vertically, with the fast component in the direction of eye movement and the slow phase towards the primary eye position
(* the amplitude of the fast component of the nystagmus is often greater with conjugate movement of the eyes towards the side of unilateral cerebellar pathology; however, strictly midline or diffuse cerebellar disease can also produce gaze-evoked nystagmus)
- sometimes the fast component of the nystagmus, that is evoked by conjugate deviation of the eyes, may suddenly change direction without any change in direction of the eyes (rebound nystagmus)
(* rebound nystagmus is very suggestive of cerebellar disease, but it is non-localizing and may even be seen in drug intoxications causing diffuse cerebellar dysfunction eg. phenytoin intoxication)
- a transient rebound nystagmus may also occur when the patient returns his eyes to the primary gaze position, and the rapid phase of the nystagmus is opposite the side from which the gaze is directed (eg. the patient who has been looking to the left develops a transient nystagmus to the right when the eyes are returned to the primary forward gaze position)
- gaze-paretic nystagmus, which is due to impaired central "gaze-holding" mechanisms, appears in lesions of the cerebellum or brainstem-cerebellar connections when the patient is looking in the same direction as the lesion, and has the same pattern as gaze-evoked nystagmus
- spontaneous downbeat vertical nystagmus or upbeat vertical nystagmus in primary forward gaze can occur, and normal optokinetic nystagmus may be dampened or disrupted
(* downbeat nystagmus is usually seen with disorders affecting the cerebellum or cervicomedullary region, while upbeat nystagmus is usually seen in cerebellar vermis lesions or intra-axial midline brainstem lesions)
- other more bizzare forms of nystagmus can also be seen eg. periodic alternating nystagmus, pendular nystagmus, divergent nystagmus, pure torsional nystagmus on vertical gaze
(* see the nystagmus guidemap for more details on nystagmus)
- gaze apraxia (problems re-directing gaze with normal extraocular apparatus function) is seen in certain hereditary ataxic syndromes, and the patient has to turn his whole head to drag his eyes onto a visual target
- gaze paresis can occur with cerebellar lesions, but it more commonly reflects an expanding posterior fossa lesion and secondary abducens nerve compression
- skew deviation of the eyes (one eye higher than the other eye on primary forward gaze, or eccentric gaze) can also be seen in cerebellar disease
- an inability to suppress the vestibulo-ocular reflex (VOR) is often present in cerebellar disease, and the VOR is tested by asking the patient to elevate the arms in front of him and fixate one thumb while slowly rotating the upper body; the normal subject can maintain fixation and the eyes do not drift away from the point of fixation during movements of the head relative to the body
- cerebellar dysarthria is usually of the spluttering-staccato type
- cerebellar spech is usually slow and slurred with unusual rhythms, and has inappropriate emphases of pitch and loudness, and articulatory impreciseness
- if the speech becomes so disturbed in rhythm and emphasis that it becomes unintelligible, it is referred to as scanning speech
- cerebellar dysarthria is thought to be due to pathology of the left paravermal zone of the cerebellum
- poor penmanship often accompanies cerebellar dysarthria and writing requires excessive concentration
- both static and kinetic tremors occur with cerebellar damage and much of the amplitude of the tremor may arise from instability of the proximal muscles of the involved limb
- the most common cerebellar tremor is a side-to-side kinetic tremor that worsens when the limb approaches the target (intention tremor)
- titubation usually refers to the head, and the rhythmic oscillations may be side-to-side, or forward-and-back or even rotatory
- the titubation may also affect the trunk
(* see the tremor guidemap for more information
on cerebellar and other tremors)
| Clinical evaluation and medical decision-making |
- the history-taking and physical examination should primarily be geared towards differentiating cerebellar ataxia from the two other common causes of ataxia - sensory ataxia and vestibular ataxia
- the clinician should search for clinical clues
that may suggest a particular pathophysiology, so that he can at least
determine the likely topographic diagnosis (site of the pathology)
| Clinical clue table - differentiating vestibular, cerebellar and sensory ataxia |
| History/exam | Vestibular | Cerebellar | Sensory |
| Vertigo |
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| Deafness, tinnitus |
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| Associated nausea, vomiting and diaphoresis |
|
|
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| Limb paresthesia or numbness |
|
|
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| Ataxia worse in the dark |
|
|
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Cerebellar signs
|
|
|
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| Nystagmus |
|
|
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| Peripheral proprioceptive sensory deficit |
|
|
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| Romberg's test |
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|
(* see the nystagmus guidemap for much greater detail on differentiating peripheral from central nystagmus; see the appendix for details on Romberg's test)
- after completing a neuro-otological examination, it should be possible to decide whether the ataxic patient has clinical signs to suggest a gait ataxia due to cerebellar disease, vestibular disease or proprioceptive sensory loss disease
- if the ataxic patient does not have any abnormal cerebellar signs or a cerebellar ataxic gait, or severe vertigo or peripheral nystagmus or deafness suggestive of vestibular disease, or evidence of proprioceptive loss in the lower limbs suggestive of sensory ataxia => specifically look for signs of basal ganglia disease, frontal lobe disease, hydrocephalus, or UMN pathology
- if the patient has an ataxic gait disorder, the presence of altered muscle tone (rigidity), bradykinesia, rest tremor, and/or spasticity, and/or urinary incontinence and/or dementia suggests the possibility of an extra-pyramidal syndrome, frontal lobe lesion, normal pressure hydrocephalus or upper motor neuron lesion => see the gait disorders, drop attacks and frequent falls guidemap for further problem-solving information
- if the symptoms and signs suggest cerebellar disease, the likely etiology depends on whether the clinical presentation is acute or chronic, and whether the pattern of cerebellar signs suggests midline cerebellar pathology, cerebral hemisphere pathology, or diffuse cerebellar pathology
- midline cerebellar pathology affecting the flocculonodular lobe often produces the following combination of signs
- unsteadiness of gait and stance when sitting or standing or walking
- severe truncal ataxia + no incoordination of the extremities while in bed
- postural sway is omnidirectional, and visual stabilization of posture is absent (absent Romberg's sign) => severe postural sway is present even with the eyes open
- dysarthria +/-
- impaired saccadic slow pursuit eye movements
- gaze-evoked, rebound, and downbeat nystagmus; impaired optokinetic nystagmus
- inability to suppress the VOR
- fine coordinated limb movements are relatively well preserved
- severe disturbance of standing and walking with relatively preserved fine coordinated movements of the upper limbs
- anteroposterior body sway of 3Hz
- visual stabilization of posture is preserved and closing the eyes increases the body tremor (presence of Romberg's sign)
- patient rarely falls because the body tremor is opposite in phase in the head, trunk and legs resulting in minimal shift in the center of gravity
- dysarthria +
- impaired dysmetric saccades
- severe ipsilateral limb ataxia (dysmetria and dysynergia)
- ipsilateral deviation of gait
- ipsilateral hypotonia (if acute)
- ipsilateral dysdiadochokinesis
- ipsilateral past-pointing
- dysarthria ++ (if left hemisphere)
- nystagmus +/-
- ocular dysmetria +/-
- bilateral limb ataxia + ataxia of stance and gait
- dysarthria ++
- multiple oculomotor disturbances (nystagmus, ocular dysynergia, ocular dysmetria and gaze palsies)
- extra-cerebellar signs (pyramidal and extra-pyramidal)
- drug intoxications (phenytoin, isopropyl alcohol, ethanol, carbamazepine, barbiturates, lithium, phencyclidine)
- volatile solvents (toluene, gasoline-additives)
- heavy metals (lead, manganese, mercury, thallium)
- cerebellitis (recent viral infection - varicella, mumps, infectious mononucleosis; bacteria, HIV)
- acute disseminated encephalomyelitis (recent immunisation or recent viral infection)
- Wernicke's encephalopathy (altered LOC, external ophthalmoplegia, ataxia, nystagmus)
- vertebro-basilar artery insufficiency
- vertebral artery dissection
- cerebellar hemorrhage or cerebellar infarction
- Miller-Fisher variant of Guillane-Barre syndrome (ataxia, external opthalmoplegia, areflexia)
- trauma (primary cerebellar trauma, subdural or epidural hematoma in the posterior fossa)
- alcoholic cerebellar degeneration (history of chronic alcohol use)
- phenytoin-induced cerebellar degeneration (history of chronic phenytoin use)
- multiple sclerosis (suggested by recurrent and multi-focal neuropathology)
- hypothyroidism (signs of myxedema - cold, dry skin and hair loss)
- paraneoplastic cerebellar degeneration (history of known malignancy, unexplained weight loss or cachexia)
- cancer patients taking cytosine arabinoside or 5-fluorouracil (causes cerebellar degeneration)
- hereditary spinocerebellar ataxias
- rare metabolic diseases (Hartnup disease, maple syrup urine disease, pyruvate carboxylase deficiency)
- Friedrich's ataxia (pes cavus, kyphoscoliosis, cardiomyopathy, posterior myelopathy, peripheral neuropathy, extensor plantar responses, spasticity, optic neuropathy)
- ataxia-telangiectasia (choreo-athetosis, loss of leg proprioception, areflexia, mental retardation, skin and conjunctival telangiectasia)
- Wison's disease
- acquired hepatolenticular degeneration
- Creutzfeldt-Jacob disease
- posterior fossa tumor (eg. medulloblastoma in children)
- posterior fossa malformations (eg. Arnold-Chiari malformation)
- multiple sclerosis
- transient vertebrobasilar ischemic attacks
- foramen magnum compression (Arnold-Chiari malformation)
- intermittent obstruction of the ventricular system
- dominantly inherited periodic ataxia
- certain clinical patterns may also suggest a likely diagnosis - localised cerebellar involvement (eg. unilateral cerebellar hemisphere involvement) suggests localised cerebellar pathology (eg. tumor or abscess or hemorrhage); while pancerebellar involvement suggests a disease causing diffuse effects (eg. drug intoxication if symptoms are acute; hereditary cerebellar degenerative disease or paraneoplastic cerebellar degeneration if the symptoms are subacute or chronic)
- the presence of a positive Romberg's test + polyneuropathy in an acutely ataxic patient, who also has definite cerebellar signs => suggests a combined cerebellar + polyneuropathy disorder, due to volatile solvents used in industry and by drug addict "huffers"; or multifocal neurological disorders like multiple sclerosis and Friedrich's ataxia if the presentation is less acute
- the combination of acute ataxia + myelopathy + altered LOC suggests an acute disseminated encephalomyelitis secondary to recent infection or immunization; the combination of myelopathy + peripheral neuropathy + ataxia suggests Friedrich's ataxia
- the combination of cerebellar ataxia + neuropathy + pyramidal signs + extrapyramidal signs + cognitive defects suggests a cerebellar degenerative disorder
- the presence of an acute cerebellar syndrome + acute brainstem signs suggests a posterior circulation stroke syndrome, or rapidly expanding posterior fossa lesion eg. bleed into a cerebellopontine angle tumor
(* pure cerebellar lesions do not cause disturbances in sensation; crossed sensory disturbances with a loss of pain sensation on one side of the face and on the opposite side of the body are common in patients with a brainstem lesion; involvement of the brainstem is also suggested by signs such as dysphagia due to lower cranial nerve involvement, facial nerve palsies, Horners syndrome, vertigo +/- hearing loss, and pyramidal long tract signs => see the appendix for further details on different patterns of posterior circulation stroke syndromes)
- the presence of an acute cerebellar syndrome + acute headache + altered LOC suggests a rapidly expanding posterior fossa lesion (eg. cerebellar hemorrhage, bleeding into a cerebellar tumor, third ventricle cyst + obstructive hydrocephalus) and/or cerebellar tonsillar herniation => an immediate MRI or CT scan is indicated
- a history of subacute headache that is worse in the morning, and on bending and coughing + subacute ataxia => suggests increased intracranial pressure due to posterior fossa pathology => MRI or CT scan indicated
(* the headache associated with a slowly expanding posterior fossa mass can be located in the occipital area or anteriorly behind the eyes)
- a diagnostic workup in the ED for a stable patient with an acute cerebellar syndrome can be initiated following consultation with a neurologist, and the workup may include blood tests (including heavy metals, serum ETOH and anticonvulsant drug levels), neuroimaging to exclude posterior fossa lesions, and CSF examination to exclude viral lymphocytic meningoencephalitis or acute disseminated encephalomyelitis - depending on the particular clinical features of the patient's clinical presentation
- chronic alcoholic patients may develop gait ataxia due to a variety of reasons (70% of cases are due to diffuse cerebellar degneration), and it is difficult to sort out the likely cause of the ataxia => see the table of cerebellar damage in chronic alcoholism for guidance
- the presence of ataxia + any of the following signs suggests a genetic disorder
- developmental delay
- episodic alteration in consciousness
- recurrent neurological symptoms
- associated movement disorders or seizures
- sudden episodes of ataxia precipitated by startle, emotions or movement
- family history of similar symptoms in a sibling or close relative
- neurologic or developmental regression
- skin lesions or rashes, or musculoskeletal abnormalities
- multi-system involvement (in addition to the CNS)
| Appendix |
- the test is primarily used to differentiate sensory ataxia from cerebellar ataxia
- Romberg's sign detects proprioceptive sensory loss by demonstrating loss of postural control in darkness
- the test is usually performed by having an examiner observing the patient's postural stability when standing with the feet close together, initially with eyes open and then with eyes closed
- Romberg's sign is present when a patient is able to stand with feet together and eyes open, but sways or falls with the eyes closed
- the test is classically positive in patients with proprioceptive loss because they are dependent on visual cues to remain in a state of postural equilibrium; however, patients with bilateral vestibular damage are also dependent on visual cues for balance and they may also have a positive Romberg's sign
- some patients* with cerebellar ataxia also have a positive Romberg's sign and they are also dependent on visual cues for maintenance of postural balance while standing
(* the pathology lies in the anterior vermis and paravermis of the anterior lobe - spincocerebellum - and is commonly due to alcohol damage; the patient has an anterior-posterior sway with a frequency of 3Hz; the patient rarely falls because the body tremor is opposite in phase in head, trunk, and legs, resulting in minimal shift of the center of gravity)
Posterior circulation stroke syndromes
- ischemic strokes involving the cerebellum often involve the brainstem, because the arteries supplying the cerebellum also supply the medulla and brainstem
- the different stroke patterns are very difficult to remember, and the following information may be used as a "memory-jogging" aid if the need arises
Superior cerebellar artery occlusion
5 distinct clinical patterns are seen
Classic SCA syndrome
- rarely seen
- ipsilateral limb dysmetria
- ipsilateral Horner's syndrome
- contralateral pain and temperature loss
- contralateral 4th cranial nerve palsy
- ipsilateral loss of emotional expression in the face
- unilateral or bilateral hearing loss
- ataxia
- +/- choreiform or athetoid movement disorders
- +/- coarse tremors
- occurs in 25% of cases of SCA occlusion
- some of the following clinical features may be present
- visual field defect, vomiting, dizziness, dipoplia, limb clumsiness, weakness, paresthesia, drowsiness
- +/- cortical blindness, memory loss or confusion, paralysis of visual fixation (Balint's syndrome)
- multimodal sensory loss
- contralateral Horner's syndrome
- ipsilateral hemianopia
- appendicular ataxia
- abulia, behavioural changes
- unilateral spatial neglect
- memory loss
- transcortical motor aphasia
- vertical gaze palsy
- third nerve palsy + contralateral limb movement disorder (Benedikt's syndrome)
- third nerve palsy + contralateral limb dysmetria (Claude's syndrome)
- third nerve palsy + contralateral limb weakness (Weber's syndrome)
- +/- pseudo sixth nerve palsy, tonic deviation of gaze, palpebral retraction, pupillary disturbances, drowsiness, hallucinosis, confusion, ipsilateral Horner's syndrome, contralateral pain and temperature loss, internuclear ophthalmoplegia
- due to embolic obstruction of the rostral end of the basilar artery
Cerebellovestibular syndrome
- due to partial SCA territory involvement
- headache, gait difficulty, dizziness, vomiting
- appendicular ataxia
- gait ataxia
- nystagmus
- dysarthria
- some brainstem signs
- due to anterior-rostral cerebellar involvement
- may mimic the dysarthria-clumsy hand lacunar syndrome
- ipsilateral limb dysmetria
- ipsilateral axial lateropulsion and gait unsteadiness
- dysarthria
- exceedingly rare
- 4 distinct clinical pictures
Classic AICA syndrome
- often mistaken for a lateral medullary syndrome; however, certain signs are unusual in lateral medullary syndrome (facial palsy, deafness, tinnitus, multimodal sensory impairment over the face)
- vertigo, vomiting, tinnitus, speech difficulty
- ipsilateral facial palsy
- ipsilateral 5th cranial nerve sensory loss
- ipsilateral Horner's syndrome
- ipsilateral appendicular dysmetria
- contralateral pain and temperature sensory loss over trunk and limbs
- +/- ipsilateral conjugate gaze palsy, dysphagia, ipsilateral limb weakness
- due to massive ventromedial involvement of the basis pons together with cerebellar infarction in the territory of all three cerebellar arteries
Isolated vertigo
- mimics acute labyrinthitis
Isolated cerebellar signs
- variable cerebellar signs
Posterior inferior cerebellar artery occlusion
- the PICA supplies the cerebellum and dorsal and lateral medulla
- three distinct clinical syndromes
Dorsal lateral medullary syndrome
- Wallenberg's lateral medullary syndrome may be complete or incomplete
- vertigo
- nystagmus
- 5th, 9th and 10th cranial nerve palsies
- ipsilateral Horner's syndrome
- appendicular ataxia
- contralateral pain and temperature loss
- ocular dysmetria, dysynergia and palsies
- vertigo, headache
- gait ataxia
- limb ataxia
- horizontal nystagmus
- ipsilateral axial lateropulsion
- mimics labyrinthitis and presents with vertigo and ataxia
- clinical clues that suggest a posterior fossa stroke (rather than
a peripheral vertigo syndrome) include age > 50, presence of vasculopathic
risk factors, direction-changing nystagmus, and normal calorics
| Cerebellar damage in chronic alcoholism |
| Anterior lobe atrophy | Diffuse cerebellar degeneration | Wernicke encephalopathy | |
| Ataxia of stance | +++ | + | +++ |
| Ataxia of gait | +++ | + | +++ |
| Gaze nystagmus | + | ++ | +++ |
| Pupillary responses | Normal | Normal | - |
| Leg dysmetria | +++ | + | + |
| Arm dysmetria | + | ++ | + |
| Polyneuropathy | (+) | +++ | + |
| Cerebral atrophy (CT) | (+) | ++ | (+) |
| Hepatic dysfunction | - | + | - |
| Altered LOC | - | - | +++ |
| Causes of sensory ataxia |
Polyneuropathy
|
Myelopathy
|
Polyneuropathy or myelopathy
|
Disclaimer: My EM guidemaps reflect my personal approach to problem-solving/managing clinical cases in an ED setting and they should not be regarded as the standard of care. They merely represent the personal opinions of the author and they should only be used in clinical practice if the reader-user has substantial reason to believe that the clinical advice contained in the guidemaps is valid and accurate. The guidemaps are not meant to be "authoritative" and the reader-user should consult standard medical textbooks and expert opinion articles/guidelines for more authoritative advice. The reader-user should particularly confirm all drug doses, their indications and contra-indications, prior to their use.