THE DIFFERENTIAL DIAGNOSIS OF VERTIGO.

A Vascular incident can be ruled out by looking for the following
central deficits:

Cerebral: MCA Occlusion . Characterised by:

Hemiparesis / Hemisensory deficit / Aphasia ( If dominant lobe is involved).

Brain stem: Proximal PICA Occlusion. Lateral Medullary Infarction ( Wallenberg's)

X Nerve involvement: Hoarseness / dysphagia

V Nerve involvement: Decreased pain / touch / temperature.

Cervical sympathetic: Horner's syndrome.

Restiform body (Cerebellum): Ataxia.

Spino-thalamic tract: Contralateral decreased pain / temperature

Cerebellum: Distal PICA Occlusion. Characterised by:

Severe rotatory vertigo with autonomic symptoms; decreased sensorium & gaze palsy are seen in accompanying medullary compression.

Vertebro-basilar insufficiency: Transient episodes of ischemia in the distribution of the vertebro-basilar system.

Characterised by: Transient vertigo

Look for other Cardiovascular disorders .

Look for the Subclavian Steal Syndrome .

Suspect Basilar Artery Migraine when headaches & nausea / vomiting are associated with symptoms of VBI in adolescent women.

VII paresis

Ipsilateral ataxia

Homonymous hemianopia

Supraclavicular bruits.

Etiology: 1. Platelet aggregation in atheromatous lesions, which dislodge & block small arterioles.

•  Associated hemodynamic & vasospastic factors.

•  Cervical spine abnormalities.

Vasculitis: Rarely seen & diagnosed, these conditions merit mention.

Temporal Arteritis

PAN

SLE

Granulomatous angiitis.

Epileptic vertigo:

a. Pre-ictal :

Either due to i. cortical lesion in that area of the temporal lobe where projections for vestibular functions exist.

Or ii. The peripheral vestibular apparatus may drive the vestibular cortex to initiate seizure discharges.

•  Post-ictal:

Due to: Hypoxia / Haemodynamic changes / Hyperventilation

c. Unrelated.

Ocular causes :
A large number of ocular conditions can give rise to the sensation of vertigo.

•  Oscillopsia: This is an illusion of back & forth movement of the environment. This is due either to a loss of VOR or a hyperactive VOR.

•  Opsoclonus: This is a horizontal & / or vertical oscillation of the eyes, seen in cerebellar & / or brainstem disorders.

•  Ocular Nystagmus: These are equal pendular excursions of the eyes because of abnormal visual fixation & / or loss of central vision.

•  Ocular vertigo ( Adler '41 ): This is a mild sensation of vertigo, which has to be differentiated from the above mentioned causes. Ocular vertigo can be caused by the following:

•  Abnormal dioptric apparatus causing a distortion of images.

•  Extra-ocular muscle weakness, causing diplopia in gaze towards the paretic muscle.

•  Optokinetic nystagmus.

•  Looking down from heights, thus causing an abolition of the vanishing point, in addition to other psychic factors.

•  Effect of sudden acceleration of the body, causing conflicting sensory input from 2 or more organs of equilibrium.

•  Abnormal dioptric apparatus causing a distortion of images.

•  Extra-ocular muscle weakness causing diplopia in gaze towards the paretic muscle.

•  Optokinetic nystagmus.

•  Looking down from heights, thus causing an abolition of the vanishing point, in addition to other psychic factors.

•  Effect of sudden acceleration of the body, causing conflicting sensory input from 2 or more organs of equilibrium.

Only when all these causes of vertigo have been ruled out can a patient be suspected to be suffering from psychogenic vertigo in the absence of other leading factors.