Thank you for your query. Am impressed with the levels of detail in your query. I d like a few clarifications, though. 1) the MRI-was it for the brain(whole brain including the posterior part) & spinal cord? If yes, what were the results? 2)did the docs say what the egg sized fluid pouch is? Does it swell or pulsate when he strains? 3)was an angiogram of the brain done? If so what were the results? 4)does he have cervical spondylosis? (narrowing of the space between the vertebrae his neck His symptoms suggest compromise of the posterior circulation of the brain & spinal cord. The two carotid arteries that run on either side of the neck supply most of the brain except for the posterior part. The vertebral artery supplies the posterior part part of the brain and arises posterior. This can be compromised by compression (cervical spondylosis, tumors, blood clots), atherosclerosis, aneurysms (ballooning of the vessel at its weak spot). AFIB can predispose to blood clots. Acoustic neuroma /vestibular schwanommas are benign tumors that affect the vestibular nerve. Their main effect is dizziness, progressively worsening tinnitus (ringing in ears) & mass effect (pressure of surrounding structures) due to its growing size I would:- : do an MRI and MRI angiogram of the whole brain, spine-to rule out tumors, aneurysm, cervical spondylosis. : check for compromise is circulation to the brain. :check for any associated neurological deficits. (in addition to a complete physical exam). In case of a tumor-size & location will determine treatment plan & prognosis. An aneurysm will need to be repaired ASAP. A blood clot would need evacuation (if too bis or causing compression) Further differentials will be based on the results of the above. Hope I ve been helpful Please get back to us for any further clarification. Wish you both good health