"Patients who exhibit extreme joint hypermobility and connective tissue weakness as a result of Ehlers-Danlos syndrome or Marfan Syndrome are susceptible to instabilities of the craniocervical junction and thus acquiring a Chiari Malformation."
Arnold Chiari Malformation is where the cerebellum (the lower, back part of the brain) and brain stem protrude, or herniate, through the foramen magnum and into the spinal cord. You may also have other conditions linked to Arnold Chiari Malformation such as hydrocephalus, syringomyelia, spinal curvature, tethered spinal cord syndrome.
There are over 100 symptoms of Arnold Chiari Malformation and your symptoms are mentioned including the conditions you have been already diagnosed with; Arnold Chiari Malformation mimics Meniere's disease and lists IBS as a symptom. A neurologist should be consulted.
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The symptoms of Chiari malformation include:
Headache -- This is the most common symptom of Chiari malformation. The headache is often pressure like and usually begins in the back of the head often radiates behind the eyes. Coughing, laughing, bending forward, sneezing or looking up can worsen the headache. Headache may be confused with migraine.
Neck Pain -- often pressure like and radiating down the spine and across the shoulders.
Dizziness/vertigo -- often worsened by extension of the neck
Vague pains throughout the body
Impaired balance
Clumsiness
Chronic nausea
Foggy thinking, poor memory and concentration
Frequent or urgent urination
Irritable bowel syndrome
Auditory Symptoms -- ringing in the ears, decrease in the ability to hear or sensitivity to sounds
Difficulty swallowing
Changes in the voice -- This can include hoarseness or the inability to regulate the voice when shouting or singing.
Visual Symptoms -- including double vision, sensitivity to light, blind spots.
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A lot of info on the Chiari Community...
http://www.medhelp.org/posts/Chiari-Malformation/Unofficial-Symptoms-List-/show/1192372