Postural control in episodic ataxia type 2: no evidence for increased vestibular excitability
Bibliographic record
Abstract
BACKGROUND AND PURPOSE: Patients with episodic ataxia type 2 (EA2) suffer from recurrent paroxysmal episodes of vertigo and oscillopsia. Pathophysiologically, altered neuronal excitability has been suspected. Vestibular excitability in 22 EA2 patients and 22 age-matched healthy participants was compared. METHODS: Galvanic vestibular stimulation (GVS) was used to assess vestibular excitability by vestibular motion perception thresholds and mean postural sway velocity during various visual and proprioceptive conditions in the two groups. Control stimuli using sham and no GVS were established to identify the specificity of GVS-induced postural sway. RESULTS: In the baseline condition, EA2 patients showed larger postural instability. However, motion perception thresholds and the increase in mean postural sway velocity during vestibular stimulation (stimulation ratio) did not differ between groups. Postural sway during suprathreshold GVS increased with the vestibular motion perception threshold in EA2 patients, in contrast to healthy participants. CONCLUSIONS: The larger postural unsteadiness of EA2 patients probably reflects their progressive cerebellar degeneration. It is not related to abnormal visual (Romberg's ratio) or proprioceptive control of stance. Postural unsteadiness during vestibular stimulation does not indicate altered vestibular excitability in EA2 patients. However, vestibular stimulation increasingly destabilized postural control of EA2 patients with higher motion perception thresholds when proprioceptive information was diminished. This conclusion, however, is restricted to the postural control of EA2 patients in the interval between the vestibulo-cerebellar episodes.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
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".