Sheep endocisternal study

The complete 2023 preprint reports twelve female Western Range sheep, approximately 40-50 kg: ten acute studies and two survival studies. The published 2024 abstract confirms sheep stimulation, recording, repositioning and explantation, but its main Methods was not accessible in this pass. The twelve-animal count is therefore a preprint figure, not an independently checked published cohort total.

The catheter/ME hardware entry explains the source boundary and configuration. Human cadaver navigation and MRI measurements are separate anatomical work, not human treatment results.

Stimulation and recording

The preprint reports catheter navigation from lumbar CSF access to spinal, frontal cortical and ventricular targets, with muscle responses and evoked potentials. Separate catheters could access brain and spinal cord simultaneously. The demonstrations do not establish restored walking, stroke recovery, epilepsy control or decoded voluntary intent.

Wireless recording used a separate ME recording implant and captured larger muscle-associated signals plus cardiac activity and stimulation artifacts. Smaller spinal potentials and cortical EEG were recorded with a benchtop system because wireless sampling and gain were limited. Those results must not be collapsed into one wireless neural-recording capability.

The published supplement includes post-euthanasia intrathecal and neck recordings showing only stimulation artifacts. This control matters when interpreting evoked traces.

Survival and removal

The preprint reports two month-long survival studies, with stimulation assessed on day 0 and day 30, followed by explantation and roughly another week of survival. Its illustrated threshold comparison gives about 6.5 mA initially and 5.5 mA at day 30. That comparison is not daily tracking in twelve animals; it does not establish stable performance across longer periods.

The preprint attributes differences in EMG amplitude to needle placement. It reports no observed neurological deficits and successful removal, but this small survival sample does not prove universal safe explantation or multi-year viability.

Inflammation and pain signal

The published supplement documents lumbar reactive vasculature with mild lymphocytic/histiocytic inflammation and rare foreign-body giant cells. Another survival sheep shows mild cervical subdural inflammation and minimal midbrain leptomeningeal inflammation. “No tissue response” would not match these findings.

Supplementary Figure 12 shows heart-rate measurements in one sheep and interprets the elevation after electrical stimulation as likely pain from stimulation of the dura. This is the authors’ interpretation, not a confirmed cause or a basis to declare the procedure pain-free. The same supplement shows no hemorrhage in the examined reverse-ventriculostomy sections, not a blanket absence of procedural risk.

What is still unverified

The published main cohort count, complete catheter fabrication details, per-animal outcomes and any changes from the preprint remain unchecked. No human clinical efficacy or full device model is supplied. More channels, longer survival, image-guided targeting and closed-loop therapy remain future work.

Primary sources

• 2023 preprint, Results and Methods.
• 2024 published article abstract.
• Published supplement, Figures 7-10 and 12-18.