Dizzines , giddiness , light headedness , fear of fall or true fall (Syncope) are the most common symptoms beyond middle age .They usually end up with consulting physicians , neurologists and cardiologists .Cervical disc is commonly blamed for this.While all these symptoms can be a manifestation of cervical disc , true syncope seems to be rare with cervical spinal disorder.
There is a fundamental ignorance here. We are not yet clear whether giddiness /dizziness is neural or vascular .(Or combinations of both ) in cervical spinal disease.
Many of the patients experience momentary unsteadiness and feel like falling but very rarely end up in a fall or syncope.By definition syncope requires global transient hypoperfusion of brain to trigger a fall .
Cervical canal carries only the vertebral artery .Both internal carotids are no where near the spine. So, however severe the vascular compromise within the cervical canal , syncope is unlikely as anterior cerebral circulation compensates at the level of circle of Willis. Is that the correct way of reasoning ? Unilateral vertebral compromise rarely matters as other side takes care.It is very unlikely both vertebral artery get compromised by cervical spinal spurs simultaneously.
How many seconds of vascular compromise is required to produce syncope ?
Brain seems to be a funny and sensitive organ .In erect posture it is very sensitive. It reacts in a fraction of time for any transient reduction of blood flow.The same cardiac events which can cause symptoms of impending syncope in erect posture is quiet comfortably tackled in recumbent posture .
In erect posture , blood pressure need to much higher to get it pumped above the heart against the gravity. Though , it seems absolute blood pressure and cerebral perfusion that matters, there is something more we are missing. The brain-stem -vestibular system perceives differently when a recumbent person develop cerebral ischemia than when he is erect . The reflex circuit that activates on/off switch for abrubt loss generalised muscular tone is not yet been identified .
It is a biologically heartening irony that syncope is a natural counter mechanism by which the organism assumes instant recumbent position to maintain perfusion of brain .A fall promptly does this.(Ofcourse with a risk of Injury )
We think more than 3 second pause will initiate a syncope circuit .But it is not a fixed number. Some can tolerate up to 5sec or even more especially in lying posture.
Syncope , as such in isolated cervical spondylosis is rare even though it can potentially interfere with the vertebro basilar system .Why the vascular compromise almost always fall short of syncope and end up with just momentry unsteadiness is not clear.
Further queries to be addressed
Is dizziness, giddiness , presyncope are vascular or neural event?
Can vertigo occur with cervival spine disease ?