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DISORDERS OF EQUILIBRIUM

Wilson D. Tulmo, M.D.

 

 

 


EQUILIBRIUM

 

-          Ability to maintain orientation in   relation to external space

-           Depends on continuous visual, labyrinthine and somatosensory inputs

 

2 CLINICAL PROBLEMS

           

1.       Vertigo

2.       Ataxia  

 

VERTIGO

 

-          Illusion of movement of the body or the environment

-          Associated symptoms:

1.       impulsion – sensation that body is being hurled or pulled in space  

2.       oscillopsia – visual illusion of moving back and forth

3.       nausea and vomiting

4.       gait ataxia

 

DISTINCTION BET. VERTIGO AND OTHER SYMPTOMS

 

-          Distinguished from nonvertiginous dizziness which includes lightheadedness, faintness or giddiness (not associated with illusion of movement).

-          In contrast, these conditions impair brain’s supply of blood, oxygen or glucose.

 

PERIPHERAL VESTIBULAR LESIONS

 

-          Labyrinth of inner ear

-          Vestibular division of the acoustic nerve

 

Central Lesions:

 

1.       Brainstem vestibular nuclei or connections

2.       Cortical

 

Table 3-1. Characteristics of Central and Peripheral Vertigo

 

 

Peripheral

Central

Vertigo

Often intermittent; severe

Often constant; Usually less severe

Nystagmus

Always present; Unidirectional, Never vertical

May be absent; Uni-or bidirectional; may be vertical

Associated findings

Hearing loss or

tinnitus

 Intrinsic brain

Stem signs

 

Often present

 

absent

 

Rarely present

 

Typically present

 

ATAXIA

 

-          Incoordination or clumsiness of movement that is not the result of muscular weakness.

-          Caused by vestibular, cerebellar or sensory (proprioceptive) disorders.

 

Table 3-2. Characteristics of Vestibular, Cerebellar, and Sensory Ataxia

 

 

Vestibular

Cerebellar

Sensory

Vertigo

Present

May be present

Absent

Nystagmus

Present

Often present

Absent

Dysarthia

Absent

May be present

Absent

Limb Ataxia

Absent

Usually present (one limb, unilateral, legs only or all limbs)

Present (typically legs only)

Stance

May be able to stand with feet together; typically worse with eyes closed

Unable to stand with feet together and  eyes either open or closed

Often able to stand with feet together and eyes open but not with eyes closed (Romberg’s sign)

Vibratory and

Position sense

Normal

Normal

Impaired

Ankle reflexes

Normal

Normal

Depressed or absent

Stance

May be able to stand with feet together; typically worse with eyes closed

Unable to stand with feet together and  eyes either open or closed

Often able to stand with feet together and eyes open but not with eyes closed (Romberg’s sign)

 

ANATOMIC BASIS OF CEREBELLAR CLINICAL SIGNS

 

A.      Midline

-          vermis and flocculonodular lobe and their subcortical (fastigial) nuclei

-          control axial functions including eye movements, head and trunk, posture, stance and gait

B.      Hemispheric

-          lateral zones

-          coordinate movements and maintain tone in ipsilateral limbs and regulate ipsilateral gaze

C.      Diffuse

 

SENSORY ATAXIA

 

-          Disorders affecting proprioceptive pathways    in:

a.       peripheral nerves

b.       sensory roots

c.       posterior columns

d.       medial lemnisci

e.       thalamic

f.        parietal lobes

 

APPROACH TO DIAGNOSIS

 

A.      History

1.       Vertigo

a.       distinguish from presyncopal sensation

b.       circumstances surrounding event

c.       look at associated symptoms

2.       Ataxia

a.       if associated with vertigo: vestibular

b.       if associated with numbness or tingling in legs : sensory ataxia

c.       unsteadiness in the dark

 

B.      Onset and Time Course

-          Sudden: infarcts and hemorrhages

-          Episodic: TIA, benign positional vertigo or Meniere’s

-          Chronic: toxic or nutritional or degenerative

 

C.   Medical History

-          Evidence of diseases

 

D.   Family History

-          hereditary:  spinocerebellar degeneration, Friedrich’s ataxia, ataxia-telangiectasia and Wilson’s disease

 

E. Physical Examination

 

a.       Orthostatic hypotension: tabes dorsalis, polyneuropathies

b.       Skin

-          oculocutaneous telangiectasia: ataxia-telangiectasia

-          dry and brittle: hypothyroidism

-          Lemon-yellow color: vit. B12 deficiency

-          Pigmented corneal ring: Wilson’s disease

-          Skeletal abnormalities

Kyphoscoliosis: Friedrich’s ataxia

Pes cavus: hereditary neuropathies

Hypertrophic or Hyperextensible Joints: tabes dorsalis

 

NEUROLOGIC EXAMINATION

 

A.      Mental Status Exam

 

1.       Acute confusional state: ethanol or sedatives and Wernicke’s encephalopathy.

2.       Dementia: Wilson’s, Creutzfeldt-Jacob, hypothyroidism, paraneoplastic syndromes and spinocerebellar degeneration.

3.       Dementia with sensory ataxia: syphilis or vit. B12 deficiency.

 

B.      Stance and Gait

 

-          Wide-based and unsteady often with reeling or lurching movements

 

C.      Cranial Nerves

 

1.       Ocular alignment

2.       Nystagmus and eye movements

3.       Hearing

4.       Positional tests

5.       Caloric testing

 

D.      Motor

 

E.       Sensory

 

F.       Reflexes

 

INVESTIGATIVE STUDIES

 

1.       Blood Studies

2.       CSF Studies

3.       Neuroimaging

4.       Evoked Potential Testing

5.       Special

-          Audiometry

-          BAEP

-          Electronystagmography (ENG)

 

PERIPHERAL VESTIBULAR DISORDERS

 

1.       Benign Positional Vertigo

2.       Meniere’s Disease

3.       Acute Peripheral Vestibulopathy

4.       Ostosclerosis

5.       Head Trauma

6.       Cerebellopontine Angle Tumor

7.       Toxic Vestibulopathies

-          Alcohol

-          Aminoglycosides

-          Salicylates

-          Quinine and Quinidine

-          Cis-platinum

8.       Acoustic Neuropathy

 

CEREBELLAR CENTRAL & VESTIBULAR DISORDERS

 

A.      Acute

a.       Drug Intoxication

b.       Wernicke’s Encephalopathy

c.       Vertebrobasilar Ischemia and Infarction

d.       Cerebellar Hemorrhage

e.       Inflammatory Disorder

-          viral or bacterial

-          ADEM, Guillain-Barre’ Syndrome

 

B.      Chronic

a.       Multiple Sclerosis

b.       Alcoholic Cerebellar Degeneration

c.       Phenytoin-induced Cerebellar Degeneration

d.       Hypothyroidism

e.       Paraneoplastic Cerebellar Degeneration

f.        Autosomal Dominant Spinocerebellar Ataxias

g.       Friedrich’s Ataxia

h.       Ataxia-Telangiectasia

i.         Wilson’s Disease

j.        Creutzfeldt-Jacob Disease

k.       Posterior Fossa Tumors

l.         Posterior Fossa Malformations