1. Vertigo:clinical syndromes(sbo-3)
Vertigo: an illusion of rotational motion, is due to asymmetry in vestibular nucleus activity.
Dizziness : also called lightheadedness.
What happens if one labyrinth is destroyed:Acute destruction or deafferation of one entire intact
labyrinth,there is a spontaneous horizontal nystagmus ,with the slow phases toward the side of the
lesion,vertigo,nausea,vomiting.These sign/symptom called acute unilateral vestibular
deafferentation.
Once vestibular compensation is complete ,so that there is a chronic stable unilateral vestibular
deafferentation.The patients will no longer experience vertigo,&most will experience no symptoms
at all. A minority of patients (20%) experience postural imbalance & visual instability.
What happens if both labyrinth are destroyed If the two labyrinths are deafferented
simultaneously,either suddenly or slowly ,the patient will not experience vertigo, since there is no
left-right asymmetry in vestibular nucleus activity.
The long term effects of bilateral vestibular deafferentation are the same irrespective of whether
unilateral vestibular deafferentation occurred simultaneously or sequentially .The patient will
experience the syndrome of chronic vestibular insufficiency,also known as Dandy’s syndrome.The
three cardinal syndromes & signs of the CVI derive from reduced input to
vestibulospinal,vestibuloocular &vestibulocortical pathway.
1)The patient with CVI cann’t walk securely in the dark, particularly if the ground is uneven because
of reduced input to vestibulospinal pathway.
2)The patient cann’t see clearly while his or her head is moving quickly,because there is reduced
input to vestibuloocular pathways,there is reduced retinal image stabilization(oscillopsia) with head
movement.
3)The patient will be disoriented when visual & propioceptive input is ambiguous.
What happens if one labyrinth is stimulated stimulation of the lateral SSC produces
horizontal beating nystagmus.Posterior SSC stimulation produces upbeating nystagmus,Superior SSC
stimulation down beating nystagmus.
When the entire labyrinth is stimulated ,the resulting nystagmus is predominantly horizontal ,since
any vertical component is concelled by opposing action of the superior (anterior ) & posterior SSC
on that side.
BPPV or Dix-Hallpike manoeuvre>Transient upbeating nystagmus(posterior SSC) or horizontal
nystagmus may occur. In patient with sound & pressure induced vestibular symptoms due to
superior semicircular canal dehiscence,the induced nystagmus is down beating.

2. Peripheral vestibular diseases
Vestibular neuritis:
is a disordered in which there is sudden ,spontaneous, isolated, total or subtotal loss of afferent
vestibular input from one labyrinth.It is common cause of the syndrome of spontaneous vertigo.
Others synonynms:Vestibular neuronitis/Labyrinthitis/Acute unilateral peripheral vestibulopathy.
Aetiology;result from a viral infection of the vestibular nerve.or selective neuronal loss in the
vestibular ganglia due to viral infection.Furthermore, latent infection of the superior & inferior
vestibular ganglia by herpes simplex virus type I. In most cases of vestibular neuritis only superior
division of the vestibular is affected.
Clinical manifestation; Acute spontaneous vertigo with nausea,vomiting, &postural imbalance. It is
typically aggravated by head movement,
Nystagmus;horizontal nystagmus.
The head rotation test; invariable results in Catch up saccades with rotation of the head towards the
affected side.
Positive Fukuda test or unterberger test; The patients will characterically rotate towards the affected
side when attempting to march on the spot with their eyes closed.
Diagnosis is a clinical diagnosis.
Management options
Steroid &antiviral valacylovir( Suspected)
Early mobilization & vestibular rehabilization is indicated.
Outcomes &complications
The acute uVD syndrome(unilateral vestibular deafferentation) invariable subsides over the
following days,due to central vestibular compensation.
In a small proportion of patients,subsequent attack on the opposite side a condition called bilateral
sequential vestibular neuritis.
20% of the patients develops typical posterior SSC type benign paroxysmal positioning vertigo on the
affected side.The afferent from posterior canal often intact,since the inferior division of the
vestibular nerve which also carries afferent from the saccule is usually spared.
In some patients the opposite occurs,-the superior division which carries afferent from
anterior(superior) & lateral SSC &uticle is spared. These patients can cause diagnostic confusion
since no nystagmus, negative head impulse test.