An often unrecognized type of Chiari Malformation in which the cerebellum is blocking the foramen magnum, but not descended through it (no herniation) or is less than the 5mm required by the diagnosis criteria. Because of its position, it is blocking the flow of cerebrospinal fluid and consequently, causing a syrinx.

Herniation involved in a Chiari Zero.

BACKGROUND: In 1997 a study was done on 5 patients that had Syringomyelia (a condition in which a CSF filled cyst forms inside the spinal cord, further compromising the spinal cord itself), but no hindbrain herniation. The presence of the syrinx was indicative of something obstructing the flow of CSF (and four were symptomatic), but because of the lack of tonsillar ectopia, they were not considered Chiari Malformations.

  • What they discovered was that the blockage of CSF alone causes problems, even serious ones like Syringomyelia.
  • This finding alone demanded a re-evaluation of all they knew about Chiari and the size-based standard adopted for a Chiari 1 malformation.

OBSTACLES IN DIAGNOSIS/TREATMENT: This study and studies since have all been very small studies that do not fit the criteria for scientific methods. However, ignoring the presence of a syrinx or pretending that there might be another potential cause for its existence other than the obstruction of cerebrospinal fluid, is negligent at best; while the cause of Syringomyelia is not always a Chiari Malformation, all studies point to it being brought on by some sort of obstruction or disruption of spinal fluid. Many sites claim Chiari Zero as controversial, but the real problem is not that it is controversial, but that medical professionals do not know (or do not known enough) about it.

Diagnosis Requirements: MRI showing no herniation of the cerebellar tonsils through the foramen magnum, but tonsils are low-lying and pressing against the top of the foramen magnum causing a syrinx (despite the name, Chiari Zero is classified under Syringomyelia and not Chiari Malformation – so a syrinx is technically required for diagnoses).

Treatment Options: With few symptoms, non-surgical treatments might be recommended. When a syrinx is present, a decompression is often recommended before the syrinx has a chance to further develop and cause additional damage to the spine. However, even when a syrinx is present, all pathological co-factors should be explored and addressed prior to decompression surgery.

Recommended Doctors: Neurosurgeon


Disc degeneration occurs when the disc space between the vertebrae dehydrate, thin, and ultimately bulge, slip, or herniate into the spinal cord. While those in the general population have an occasional disc problem, those with a connective tissue disorder such as Ehler’s-Danlos Syndrome, tend to have multiple discs with signs of degeneration (either in a single level (cervical, thoracic, or lumbar) or in the entire spine itself) and it is then considered Degenerative Disc Disease.

Etiological Co-factor: Heritable Disorders of Connective Tissue (HDCT), such as Ehlers-Danlos Syndromes (EDS).

A chronic and often progressive neurological condition in which a cyst (syrinx) fills with cerebrospinal fluid (CSF) inside the brainstem, often starting as a syrinx in the spinal cord (Syringomyelia) and extending upward into the medulla (bulbar area) of the lower brainstem (Syringobulbia). This cyst can enlarge and further compromising the brainstem. The extent of damage done by a syrinx in brainstem often depends on the size of the syrinx.

The exact reason syrinxes form is not quite clear, but they are believed to form from the blockage of CSF, just above the point of blockage (such as that consistent with a Chiari malformation, Spina Bifida, Tethered Cord Syndrome, a spinal cyst, a herniated disc, a spinal cord trauma/injury, or even meningitis can cause inflammation that can obstruct the flow of CSF).

Symptoms Include: Dizziness (vertigo; sometimes accompanied by nausea/vomiting); difficulty swallowing (dysphagia); problems breathing; snoring/sleep apnea; involuntary rapid movement of the eyeball (nystagmus); facial numbness/palsies/paralysis; small involuntary muscle contractions of the tongue (fibrillation); stuttering; hoarse voice (dysphonia); hearing loss; ringing in the ears (tinnitus); Dysautonomia