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Flashcards in CN LANGE - Disorders Of Equilibrium III Deck (99):
1

Wernicke encephalopathy is an acute disorder comprising the clinical triad of:

1. Ataxia.
2. Ophthalmoplegia.
3. Confusion.

2

Wernicke encephalopathy may occur as a consequence of ...?

MALNUTRITION OF ANY CAUSE (not just chronic alcoholics).

3

Wernicke encephalopathy - Clinical findings - Cerebellar and vestibular involvement:

BOTH contribute to ataxia --> Affects gait primarily or exclusively.
--> Legs in 20%.
--> Arms in 10%.

4

Other findings of Wernicker encephalopathy:

1. Amnestic syndrome or global confusional state.
2. Horizontal or combined horizontal/vertical nystagmus.
3. Bilateral LATERAL RECTUS palsy.
4. Absent ankle reflexes.
5. Caloric testing may show bilateral/unilateral vestibular dysfunction.
6. Conjugate gaze palsy, pupillary abnormalities, and hypothermia can also occur.

5

Wernicke encephalopathy - Diagnosis and treatment:

Diagnosis --> Confirmed by the clinical response to thiamine (100mg IV).
Ocular palsies tend to improve within HOURS.
Ataxia, nystagmus and confusion within a few DAYS.
--> Horizontal nystagmus may persist.

6

Wernicke encephalopathy - Ataxia is fully reversible in only ...?

Approximately 40% of patients, in whom full recovery typically takes WEEKS to MONTHS.

7

Vertebrobasilar ischemia and infarction - The internal auditory artery may originate from the ...?

Basilar or AICA.

8

Internal auditory artery occlusion:

Vertigo of central vestibular origin and unilateral sensorineural hearing loss --> Vertigo is accompanied by NYSTAGMUS --> Fast phase AWAY from the involved side.

9

Lateral medullary infarction - Usually caused by ...?

Proximal vertebral artery occlusion --> Wallenberg syndrome.

10

Wallenberg syndrome - Clinical manifestations vary, depending on the extent of infarction - Vestibular nuclei involvement:

Vertigo + nausea + vomiting + nystagmus.

11

Wallenberg syndrome - Clinical manifestations vary, depending on the extent of infarction - Involvement of dorsal motor X nucleus + nucleus solitarius + nucleus ambiguous:

Hoarseness and dysphagia.

12

Wallenberg syndrome - Clinical manifestations vary, depending on the extent of infarction - Involvement of the descending SNS tract + inferior cerebellar peduncle + spinal nucleus and tract of V:

Ipsilateral HORNER + Limb ataxia + Loss of ALL FACIAL SENSATION + Loss of light touch and position sense in the limbs.

13

Wallenberg syndrome - Clinical manifestations vary, depending on the extent of infarction - Involvement of the spinothalamic tract:

Contralateral impaired pin and temperature sense in the limbs.

14

Cerebellar infarction - Cerebellar blood supply:

Superior cerebellar + AICA + PICA --> The territory supplied by each of these vessels is highly variable, both from one individual to another and between the 2 SIDES in a given patient.

15

The superior + middle + inferior cerebellar peduncles are typically supplied by:

Superior p. --> Superior cerebellar artery.
Middle p. --> AICA.
Inferior p. --> PICA.

16

Signs of cerebellar infarction include:

1. Ipsilateral limb ataxia lateropulsion (falling TOWARD or, less commonly, AWAY from the side of the lesion).
2. Hypotonia.

17

Cerebellar infarction - Other signs/symptoms that may also occur:

1. Headache.
2. Nausea, vomiting, vertigo, nystagmus.
3. Dysarthria.
4. Ocular/gaze palsies.
5. Facial weakness or sensory loss.
6. Contralateral hemiparesis or hemisensory deficits.

18

How do we distinguish occlusion of the superior cerebellar, AICA, or PICA?

ONLY BY BRAINSTEM FINDINGS, if AT ALL.

19

Cerebellar infarction - Diagnosis:

By CT or MRI, which differentiates between infarction and hemorrhage, should be obtained promptly.

20

Paramedian midbrain infarction - Caused by ...?

Occlusion of the paramedian penetrating branches of the BASILAR artery.

21

Paramedian midbrain infarction - Affects:

The III nerve root fiber + red nucleus --> BENEDIKT SYNDROME.

22

Benedikt syndrome - Clinical features:

1. III nerve involvement --> Medial rectus palsy + fixed dilated pupil.
2. CONTRALATERAL limb ataxia (typically affecting only the arm).

23

Benedikt syndrome - Cerebellar symptoms result from involvement of the ...?

RED NUCLEUS - Receives a crossed projection from the cerebellum in the ascending limb of the SUPERIOR CEREBELLAR PEDUNCLE.

24

Cerebellar hemorrhage - Hypertensive cerebellar hemorrhages are usually located in the ...?

Deep white matter of the cerebellum and commonly extend into the 4th ventricle.

25

Cerebellar hemorrhage - Clinical findings: - Sudden onset of ...?

HEADACHE - Accompanied by nausea + vomiting + vertigo, followed by GAIT ATAXIA and IMPAIRED CONSCIOUSNESS usually evolving over HOURS.

26

Cerebellar hemorrhage - Gaze palsy?

IPSILATERAL gaze palsy - with gaze preference AWAY from the side of the hemorrhage + IPSILATERAL peripheral FACIAL PALSY --> COMMON.

27

Cerebellar hemorrhage - The patient, if alert, exhibits ataxia ...?

OF STANCE + GAIT --> Limb ataxia is LESS COMMON.

28

Cerebellar hemorrhage - The diagnosis may be delayed or missed if ...?

Gait is not tested promptly in EVERY PATIENT with HTN + either acute headache or depressed consciousness.

29

Prominent feature of intoxication with ethanol, sedative-hypnotics, anticonvulsants, and hallucinogens:

PANCEREBELLAR dysfunction --> Nystagmus + dysarthria + limb/gait ataxia.

30

Inflammatory disorders - Cerebellar ataxia by viral infection is a manifestation of ...?

1. St. Louis encephalitis.
2. HIV dementia.
3. Meningoencephalitis due to varicella, mumps, poliomyelitis, infectious mononucleosis, or lymphocytic choriomeningitis.

31

Bacterial infection as a cause of cerebellar ataxia:

UNCOMMON, but ... 10-20% of brain abscesses are located in the cerebellum, and ataxia may be the feature of meningitis due to Listeria in adults or Haemophilus in children.
--> Legionella can ALSO produce a cerebellar syndrome without clinical evidence of meningitis.

32

Acute cerebellar ataxia of childhood:

Characterized by SEVERE gait ataxia that follows an acute viral infection or vaccination and usually resolves COMPLETELY within months.

33

Acute disseminated encephalomyelitis:

1. Idiopathic, immune-mediated DEMYELINATION in the cerebellar white matter.
2. May produce ataxia, often associated with:
a. Impaired consciousness.
b. Seizures.
c. Focal neurologic signs.
d. Myelopathy.

34

Fisher Variant of Guillain-Barre syndrome:

1. Ataxia.
2. Ophthalmoplegia.
3. Areflexia.
--> Presents more typically with ascending paralysis.
--> Symptoms develop over few days.

35

Fisher variant of Guillain-Barre syndrome - Clinical features:

1. Ataxia primarily affects gait and trunk.
2. Dysarthria is UNCOMMON.
3. CSF protein may be elevated.
4. Resp. insufficiency is RARE, and the usual course is a gradual and often COMPLETE recovery over WEEKS to MONTHS.

36

Summary - Cerebellar and central vestibular disorders - Inflammatory disorders:

1. Viral infection.
2. Bacterial infection.
3. Acute cerebellar ataxia of childhood.
4. Acute disseminated encephalomyelitis (ADEM).
5. Fisher variant of Guillain-Barre syndrome.

37

Cerebellar and central vestibular disorders - Chronic disorders - Vestibular migraine:

EPISODIC vertigo + other features of migraine attacks.

38

Cerebellar and central vestibular disorders - Chronic disorders - Multiple Sclerosis - Clinical findings:

1. Nystagmus (very common).
2. Dysarthria.
3. Vertigo (less often).
4. Gait ataxia --> 10-15% of patients usually due to CEREBELLAR involvement.
5. Limb ataxia is common --> Bilateral, affect either BOTH legs or ALL 4 limbs.

39

Cerebellar and central vestibular disorders - Chronic disorders - Alcoholic cerebellar degeneration:

Degenerative changes in the cerebellum are largely restricted to the SUPERIOR VERMIS --> Also the site of involvement in Wernicke encephalopathy.

40

Alcoholic cerebellar degeneration is most common in ...?

MEN --> 40-60.

41

Most patients with alcoholic cerebellar degeneration have also ...?

Other medical complications of alcoholism.

42

Course of alcoholic cerebellar degeneration:

Insidious onset --> Progresses gradually over WEEKS/MONTHS, eventually reaching a plateau of dysfunction.
--> In occasional cases, ataxia appears abruptly.

43

Alcoholic cerebellar degeneration - What is a universal and almost always the problem that brings the patient to attention?

Gait ataxia.
--> Legs are ataxic on heel-knee-shin testing in approx. 80% of patients.

44

Alcoholic cerebellar degeneration - Treatment:

1. No treatment is available.
2. Should receive THIAMINE, due to close relation with Wernicke encephalopathy.
3. Abstinence from alcohol, combined with adequate nutrition, may help prevent progression.

45

Cerebellar and central vestibular disorders - Chronic disorders - Toxin-induced cerebellar degeneration - Which 2 cerebellar cells are particularly vulnerable to a variety of toxins?

1. Purkinje cells.
2. Granule cells.

46

Toxin-induced cerebellar degeneration - The toxin-induced degeneration of Purkinje and granule cells may cause ...?

1. Nystagmus.
2. Dysarthria.
3. Ataxia --> Limbs, trunk, gait.

47

Toxin-induced cerebellar degeneration - Toxins:

1. Alcohol (as discussed).
2. Phenytoin.
3. Lithium.
4. Amiodarone.
5. Fluorouracil.
6. Cytarabine.
7. Toluene.
8. Lead.
9. Mercury.
10. Thallium.

48

Toxin-induced cerebellar degeneration - Reversibility?

May be IRREVERSIBLE.

49

Cerebellar and central vestibular disorders - Chronic disorders - Hypothyroidism:

A subacute or chronically progressive cerebellar syndrome, which is MC in middle-aged + elderly women.

50

Hypothyroidism - Universal and most prominent finding?

GAIT ataxia.

51

Cerebellar and central vestibular disorders - Chronic disorders - Paraneoplastic cerebellar degeneration - Which cancers especially associated?

1. Lung cancer (small cell).
2. Ovarian cancer.
3. HL.
4. Breast cancer.

52

Paraneoplastic degeneration affects the cerebellar ...?

VERMIS + HEMISPHERES diffusely.

53

Paraneoplastic cerebellar degeneration - Pathogenic mechanism in many cases:

ONCONEURAL antibodies --> Cross-react with tumor cell and Purkinje cell antigens.

54

Paraneoplastic cerebellar degeneration - Course:

Usually progresses steadily, BUT it may stabilize or go into REMISSION with treatment of the underlying neoplasm.

55

Paraneoplastic cerebellar degeneration - Clinical findings:

1. Gait and limb ataxia = Prominent.
2. Dysarthria in most cases.
3. Limbs may be affected ASYMETRICALLY.
4. Nystagmus is rare.

56

Paraneoplastic cerebellar degeneration - Diagnosis:

Onconeural antibodies:
1. Anti-Yo.
2. Anti-Hu.
3. Anti-Ri.
--> Can sometimes be detected in the blood.

57

Anti-Yo:

Ovarian and breast cancer.

58

Anti-Hu:

Small cell lung cancer.

59

Anti-Ri:

Breast cancer.

60

Paraneoplastic cerebellar degeneration - What helps to distinguish this from the cerebellar symptoms produced by chronic alcoholism or hypothyroidism?

The frequent occurrence of dysarthria + dysphagia.
--> Ataxia of the ARMS also suggests that alcohol is an UNLIKELY cause.

61

Anti-Hu - CNS and peripheral NS associations:

CNS:
1. Cerebellar degeneration.
2. Limbic encephalitis.
3. Encephalomyelitis.
PNS:
1. Sensory neuronopathy.

62

Anti-Yo:

Cerebellar degeneration.

63

Anti-Ri:

1. Cerebellar degeneration.
2. Encephalomyelitis.

64

Anti-CV2:

1. Cerebellar degeneration.
2. Encephalomyelitis.

65

Anti-Ma:

1. Cerebellar degeneration.
2. Limbic encephalitis.

66

Anti-amphiphysin:

1. Cerebellar degeneration.
2. Limbic encephalitis.
3. Encephalomyelitis.
4. Stiff-person.

67

Anti-Tr:

Cerebellar degeneration.

68

Anti-Zic4:

Cerebellar degeneration.

69

Anti-mGluR1 (metabotropic glutamate receptor, type1):

Cerebellar degeneration.

70

Anti-VGKC (voltage-gated K channel):

1. Limbic encephalitis.
2. Neuromyotonia.

71

Anti-VGCC (Voltage-gated Ca channel):

1. Cerebellar degeneration.
2. Lambert-Eaton syndrome.

72

AD spinocerebellar ataxia (SCA) - At least 3 TYPES of mutations can produce AD SCA:

1. Expansion of CAG trinucleotide repeats coding for polyglutamine (polyQ) tracts.
2. Expansion of tri- or pentanucleotide repeats in noncoding regions.
3. Point mutations.

73

AD SCA - MC type of mutation:

The polyQ disorders are the MC and best characterized --> Affect a wide range of proteins --> Ion channels, receptors, enzymes, and cytoskeletal proteins.

74

Striking feature of polyQ disorders is ...?

ANTICIPATION --> The trinucleotide expansion is UNSTABLE and tends to enlarge with time.

75

In addition to SCAs, polyQ disorders include:

1. Spinal bulbar muscular atrophy (Kennedy disease).
2. Huntington disease.

76

PolyQ expansions confer a ...?

TOXIC gain of function on the target protein.

77

AD SCAs - Clinical findings:

1. Adult-onset.
2. Slowly progressive cerebellar syndrome in which GAIT ATAXIA --> Early and prominent feature.
3. Dysarthria, diplopia, and limb ataxia.

78

AD SCAs - Extracerebellar findings:

Common:
1. Cognitive.
2. Pyramidal.
3. Extrapyramidal.
4. Motor neuron.
5. Peripheral nerve.
6. Macular involvement.

79

Which AD SCAs are the MC:

1+2+3+6+7.

80

SCA1:

1. Gait ataxia.
2. Limb ataxia.
3. Dysarthria, with brainstem involvement but little cognitive abnormality.

81

SCA2:

Notable for the association of ataxia and dysarthria with slow saccadic eye movements and polyneuropathy.

82

SCA3:

1. Common in Portuguese ancestry.
2. Ataxia is accompanied by eyelid retraction + reduced blinking + external ophthalmoplegia.
3. Dysarthria, dysphagia.
4. Parkinsonism or peripheral neuropathy.

83

Another name for SCA3:

Machado-Joseph disease.

84

SCA6:

Comparatively less severe, progresses more slowly, and is more limited to cerebellar involvement than other SCAs.

85

SCA7:

Distinguished by RETINAL DEGENERATION --> Blindness, in addition to ataxia.

86

SCA - Definitive diagnosis is by ...?

Genetic testing.

87

Mention 2 other AD cerebellar ataxias:

1. Dentatorubral Pallidoluysian atrophy.
2. Episodic ataxias.

88

Dentatorubral pallidoluysian atrophy:

AD disorder that results from a polyglutamine expansion in the ATN1 gene --> Coding for protein atrophin 1.

89

DRPLA causes:

1. Ataxia.
2. Chorea.
3. Dementia.
4. Seizures.
5. Myoclonus.
--> Prominent extrapyramidal features.

90

Episodic ataxias:

AD disorders characterized by transient attacks of cerebellar ataxia that may be precipitated by physical or emotional stress.

91

Episodic ataxia 1 (EA1) - Mutation:

KCN1A --> Kv1.1 voltage-gated potassium channel.

92

EA1 - Attacks:

1. Seconds to minutes.
2. Many times per day.
3. Myokymia --> Commonly occurs between the episodes.

93

EA2 - Mutation:

CACNA1A --> Codes for the α1A subunit of the P/Q-type voltage-gated calcium channel.

94

EA2 - CACNA1 gene is also affected in ...?

1. SCA6.
2. Familial hemiplegic migraine.

95

EA2 - Attacks:

1. More prolonged than in EA1 --> Lasting hours.
2. Nystagmus + slowly progressive ataxia persists between acute episodes.

96

EA2 - Management:

Acetazolamide (500mg ORALLY 4x daily) --> Can often prevent or relieve acute symptoms in EA2.

97

EA5 - Mutation:

Voltage-gated calcium channels --> CACNB4 --> Encodes the beta subunit.

98

EA6 mutation:

SLC1A3 --> Encodes the EAAT1 glial glutamate transporter.
--> Glutamate uptake is reduced, leading to enhanced excitatory input onto cerebellar Purkinje cells.

99

EAs - Sum of mechanisms:

EA1 + EA6 --> Are thought to impair channel function through dominant negative effects.
EA2 --> Involves haploinsufficiency.
EA5 --> Uncertain mechanism.