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Learn how the balance system works, what can go wrong in the system, how do we figure things out and what can we do to fix things.
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Balance Disorders: Dizziness and Vertigo
Jed A. Kwartler MD, MBA
Dina Leyden PT
Gina Byrnes MSW, LCSW
What we will talk about
• How does the balance system work• What can go wrong in the system• How do we figure things out• What can we do to fix things
Why do we need a balance system?
• Balance, posture• Vestibular• Vision• Proprioception (ankle, etc)
• Stable sensory platform• Especially for vision
• Spatial orientation• Which way is up• Important in space, underwater,
in the air, and in underground tunnels
Organization of Balance System
Anatomy
Canal anatomy• Each canal has a swelling at
its base, called the ampulla
• The crista is a saddle--shaped receptor epithelium covered with hair cells
• The stereocillia of the cells are embedded in a gelatinous membrane (the cupula) that spans the ampulla and forms a barrier across it
The three semicircular canals lie in 3 orthogonal planes
Cochlear N
Vestibular N
HorizontalCanal
Vestibulo-Cochlear N
(Nerve VIII)
Cochlea
PosteriorVerticalCanal
AnteriorVerticalCanal
Canal orientation
The three semicircular canals are approximately orthogonal to each other. One is 30 deg above horizontal, while the anterior and posterior are vertical (approximately 45° from the sagittal plane)
Notice that they are arranged in pairs:
R Horizontal -- L Horizontal
R Anterior -- L Posterior
R Posterior -- L Anterior
The semicircular canals are functionally paired to eye muscles
• The canals lie in roughly the same planes as the extraocular muscles:
Horizontal canals: lateral and medial recti.LARP: left vertical recti, right obliques.RALP: right vertical recti, left obliques.
• Each canal excites a pair of muscles and inhibits a pair of muscles in its plane. Its partner excites the muscles it inhibits, and vice-versa.
Canal function
• When the head rotates, inertia causes the fluid in the canals to lag behind, exerting force on the cupula, which in turn bends the stereocillia
• Ipsilateral rotation is excitatory, contralateral is inhibitory; each canal pair works as a push-pull system
There are 3 major vestibular reflexes
• Vestibulo-ocular reflex – keep the eyes still in space when the head moves.
• Vestibulo-colic reflex – keeps the head still in space – or on a level plane when you walk.
• Vestibular-spinal reflex – adjusts posture for rapid changes in position.
First step – Take a history
What are we looking for in the history
• Describing what the sensation feels like• When and how did it start• Pattern
Constant, episodic, getting worse or better• What makes it worse, makes it better
Foods, activities, movements, time• Associated symptoms
Headache, sensorimotor changes, metabolic • Other factors
Sleep, stress, medications, mobility, general condition
Physical Examination
• Orthostatic blood pressure• General head and neck exam• Otoneurologic exam
Eye movements Postural control and coordination Provocative movements
• “testing for crystals”• Visual fixation/suppression of nystagmus• Dynamic visual acuity with head movement• Dizziness/nystagmus with air pressure or loud sound
Testing
• Hearing test• Tests of balance function
VNG Rotary Chair Posturography Head thrust VEMP (cervical or ocular)
• Functional balance assessment by PT
Vestibular• Menieres• Vestibular Neuritis• Benign position vertigo• Idiopathic recurrent vestibulopathy
Neurologic• Migraine• Concussion• Stroke/Ischemia• Neuropathy• Visual disturbance
Other• Cardiac – pressure, output, arrythmia, postural• Medications• Metabolic – endocrine• Sleep apnea• Stress/anxiety• Mobility and general conditioning