Posterior Fossa Arachnoid Cyst Associated with Chiari I and Syringomyelia
Bibliographic record
Abstract
The association of posterior fossa (PF) lesions with syringomyelia has been described occasionally both for solid and cystic abnormalities.Few cystic lesions of the PF have been found in association with syringomyelia, and even fewer are believed to cause cavitation of the spinal cord by descent and impaction of the cerebellar tonsils into the subarachnoid space at the level of the foramen magnum (FM).We describe a case of a PF arachnoid cyst associated with impairment of the cerebrospinal fluid (CSF) flow at the FM and syringomyelia. CASE REPORTThis 61-year-old woman had delayed developmental milestones, and never used her right arm and hand to the full extent.She reported that at an early age 'electrical treatments' were given to improve the condition of her right arm.It was predicted that she would have great difficulty with her studies, yet she obtained a university level education.In 1994 she presented with her longstanding weakness of the right arm, as well as numbness of the right side of the face extending to the ipsilateral shoulder region.The patient was managed conservatively until early 2006.At this time she complained of disagreeable sensations of her right face and right upper limb, and was noted to have 4/5 weakness of the right shoulder abductors and elbow flexors.When she came to surgical attention prior investigations had identified a 75 x 35 mm arachnoid cyst, extending from the right sigmoid sinus to the clivus, with compression and deformation of the cerebellum, IV ventricle and brain stem.There was no hydrocephalus.Crowding of the FM area was observed, but there was no overt descent of the tonsils below the FM.An 8 mm in diameter syrinx was seen from the cranio-cervical junction down to T10 (Figure 1).Two weeks before her scheduled surgery she complained of double vision and extension of the numbness down the right upper and lower limb.She was taken to the operating room and an endoscopic fenestration of the cyst was performed February 2006.Her double vision disappeared and so did the leg symptoms, but her distressing paresthesias were still present.An MR CSF flow study revealed minimal CSF flow at the FM.In June 2006 the patient underwent a right PF craniotomy for a larger fenestration of the arachnoid cyst into the cisternas of the posterior fossa.There was no significant change in her symptoms.The arachnoid cyst decreased minimally in size.Later, she reported swallowing and breathing difficulty, and it was hard for her to walk and talk simultaneously.In October 2006 a FM decompression with duroplasty was performed.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.005 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.002 | 0.003 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.003 | 0.004 |
| Insufficient payload (model declined to judge) | 0.005 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".