Giddiness Flashcards
What is vertigo?
The incorrect perception of relative motion between the individual and their environment. This usually causes postural instability and they have to lie or sit down.
What are the different sensations in vertigo and what are they caused by?
The sensation may be of rotation (semi-circular canal dysfunction) or undulation like being on the deck of a ship (otolith dysfunction)
What is vertigo due to physiologically?
Due to a mismatch between sensory inputs involved in maintaining posture. These are the visual, proprioceptive and vestibular systems.
70% of vertigo is caused by which 4 syndromes?
Benign paroxysmal positioning vertigo
Meniere’s disease
Vestibular neuritis
Phobic vertigo
Which 2 areas does vertigo stem from?
Peripheral vestibular dysfunction arising from the vestibular structures in the ears
Lesions affecting the central vestibular connections within the brain stem.
Which disease does intermittent, positional vertigo suggest? What is it caused by?
Benign paroxysmal positioning vertigo (BPPV).
It follows a viral infection or head trauma. The patient is often bed bound because getting up triggers vertigo and vomiting.
What other things can cause intermittent, positional vertigo?
Alcohol intoxication
Anticonvulsant intoxication
What is the test for benign paroxysmal positional vertigo? What happens when it is positive?
Hallpike’s manoeuvre test may elicit the typical abnormality in BPPV - the patient is rapidly lowered down into the position which elicits vertigo (head lower than body and face to one side).
There is a delay of several seconds before nystagmus and then a rotatory component towards the lower ear. Both the vertigo and nystagmus pass quickly.
What is the main cause of intermittent non-positional vertigo? What are its symptoms?
Meniere’s disease.
Middle-ages patients typically suffer episodes lasting hours with associated hearing loss. During the episodes there is nystagmus and between episodes is a decline in hearing.
What are other causes of intermittent non-positional vertigo?
Peripheral causes - otosclerosis, hyperviscosity syndromes, syphilitic labyrinthitis and Cogan’s syndrome.
CNS causes - multiple sclerosis, vertebrobasilar ischaemia.
(CNS causes will be associated with other brainstem dysfunction symptoms such as ataxia, diplopia, cranial nerve or limb defects).
What is the commonest cause of sustained vertigo? What is it’s pathology?
Idiopathic vestibular neuritis.
Thought to be caused by infection. Important ones to note are syphilis, tuberculosis and Lyme’s disease.
Herpes zoster can also cause acute vertigo (as well as unilateral hearing loss, ipsilateral facial paresis, severe pain, malaise and characteristic herpetic vesicles (Ramsay Hunt syndrome) - treated with acyclovir).
What is the vestibulo-ocular response testing? What is involved?
Testing the pathways between the vestibular system and the nuclei controlling eye movements. You get the patient to look at you and then move their head from side to side as well as up and down - the patient’s eye should remain looking at your eye, if it doesn’t there is a lesion of the VOR.
What is caloric testing and why is it used?
It is when water is introduced into one of the external auditory canals at 32C and 41C. This causes nystagmus. The Cold water causes the fast phase of nystagmus to the Opposite side, Warm water causes it to the Same side (COWS).
It assesses and quantifies the functional status of the individual vestibular systems.
What do auditory evoked potentials measure?
The delay in central auditory pathways, especially in MS.
What is the investigation of choice in central vestibular disturbance?
MRI scan.
A CT brain scan may miss posterior fossa lesions, especially small acoustic Schwannomas, and will miss demyelination.
