Microelectrodes in Epilepsy: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Microelectrodes in Epilepsy (NCT05200455), a na na study. The primary outcome is Feasibility of Microelectrode Technology to Isolate Place Responsive Neurons in the Human Hippocampus as Measured by the Number of Place Responsive Neurons..

2. Clinical Question

The study also lists a secondary question about whether neural activity frequencies—alpha, beta, delta, theta, gamma, and high-gamma—predict performance speed during a cognitive task, with accuracy measured in percentage. The record does not provide the result for this secondary outcome, or explain how prediction was assessed.

These questions concern technical feasibility and recorded neural activity during monitoring. They are not framed as a comparison of clinical outcomes between treatment groups. The primary endpoint is a count, while the secondary question relates neural-frequency measurements to task performance. Neither a primary count nor a secondary-outcome estimate is reported in the registry record, so the clinical question can be described, but its answer cannot be determined from the posted results.

3. Trial Design

NCT05200455, titled “Microelectrodes in Epilepsy,” is listed as completed. The registry lists Dartmouth-Hitchcock Medical Center as sponsor and epilepsy as the condition. The listed enrollment is 34. The study start date is 2009-09-18, and the primary completion date is 2021-03-30. Phase is listed as NA.

The design is identified as single-group, with allocation listed as NA and masking listed as none. Participants qualifying for the study were described as receiving standard electrodes alongside microelectrodes for intracranial seizure monitoring. Because there is no separate control arm, the design does not support a randomized between-group treatment contrast. The registry does not report a protocol-based comparator or a statistical plan for comparing outcomes with an external group.

The primary endpoint is to be evaluated for each patient during a monitoring period of approximately 2 weeks. The described implantation approach is occipito-temporal, and the endpoint focuses on whether place-responsive neurons can be isolated. The population description refers to patients undergoing intracranial EEG monitoring for TLE and implanted with depth electrodes and microelectrodes. The number who completed monitoring or contributed endpoint data is not reported in the registry record.

The registry lists 2 outcome measures and 0 analyses. It does not report results for the primary neuron-count endpoint or the secondary cognitive-task question. Details such as eligibility criteria, recruitment flow, protocol deviations, and the analysis population are not reported in the registry record. The completion status therefore describes the administrative study status; it does not establish that the posted record contains analyzed results for the stated questions.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Participants included patients undergoing intra-cranial EEG monitoring for TLE and are implanted with depth electrodes and microelectrodes via the trans-occipital approach. The total number of place responsive neurons recorded from all participants is reported below.

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Feasibility of Microelectrode Technology to Isolate Place Responsive Neurons in the Human Hippocampus as Measured by the Number of Place Responsive Neurons., measured over Evaluated for each patient during monitoring period of approximately 2 weeks.

The primary endpoint is the number of place-responsive neurons that could be isolated using microelectrodes implanted through the occipito-temporal approach. It is a count outcome, described as a measure of feasibility in the human hippocampus. The stated timeframe is evaluation for each patient during a monitoring period of approximately 2 weeks. The outcome description also refers to the total number of place-responsive neurons recorded from all participants.

A count is relevant to a feasibility question because it records whether the intended type of neural response could be identified, and how many such neurons were isolated. It does not, by itself, indicate how consistently the result occurred across participants. A total across participants and a participant-level distribution answer different descriptive questions; the registry does not report either numerical result. In particular, it does not give the number of participants with any place-responsive neurons, the counts for individual participants, or a summary of variability.

Without the observed count and its participant-level context, the endpoint cannot be interpreted quantitatively. The record also does not report a threshold for what would constitute successful feasibility, or a confidence interval for the endpoint. Those details are not reported in the registry record. The endpoint’s stated purpose is technical feasibility, not a measure of seizure control or another clinical benefit.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the primary outcome as a count: the number of place-responsive neurons isolated. Count outcomes differ from measurements that can take any value along a continuous scale. They record occurrences, and their distributions can be uneven, with many low values and a smaller number of high values. Whether that pattern occurred in this study cannot be determined because the outcome data are not reported.

What does a count endpoint capture?

The endpoint is intended to capture whether the microelectrode approach yielded identifiable place-responsive neurons. A total count can communicate the amount recorded across participants, but a total alone does not show how the observations were distributed among participants. For example, the same total could arise from relatively similar participant-level counts or from counts concentrated in a small number of participants. This is a general feature of aggregated count data, not a claim about the pattern in this study.

Participant-level counts, a summary of their distribution, and the number of participants contributing data would help describe the endpoint more fully. The registry record does not report those results. The outcome description says that the total recorded from all participants is reported, but no numerical total appears in the registry information available for this analysis.

Why can over-dispersion matter?

In general, count-data models may rely on assumptions about how much variability is expected at a given average count. Over-dispersion occurs when observed variability is greater than a model’s basic assumptions allow. If over-dispersion is present and ignored, standard errors may be too small and uncertainty may be understated. This is a general statistical consideration; the registry does not report a model, a variability estimate, or an assessment of over-dispersion for this study.

Counts can also depend on the amount of opportunity to observe them. Here, the endpoint description gives a monitoring period of approximately 2 weeks per patient and describes implantation with depth electrodes and microelectrodes. The record does not specify recording duration within that period, the number of usable recording sessions, or how those factors were handled analytically. It would be inappropriate to assume that observation opportunities were identical across participants.

What can a single-group design estimate?

A single-group study can describe measurements collected under its study conditions. It does not, on its own, estimate a difference against a concurrently assigned control group. This distinction matters when interpreting feasibility: observations may inform whether the recording approach yielded the targeted signals in the studied setting, but there is no randomized comparator in this design from which to estimate a relative effect.

The registry lists allocation as NA, masking as none, and the model as single-group. It lists 0 analyses, and no statistical model, test, or adjusted estimate is reported. The posted record therefore does not support an account of how the primary count was analyzed. Nor does it report an inferential estimate with a confidence interval. In general, a confidence interval expresses uncertainty around an estimate under the assumptions of the method used; it does not replace reporting the underlying outcome or analysis population.

How should the planning illustrations be read?

The registry’s stated sample-size assumptions describe planning illustrations computed from an observed effect, not the study’s own design. They specify a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The illustrations are described as participants per arm except for time-to-event outcomes, which use a total number of events. The registered study, however, is single-group rather than a two-arm comparison. These assumptions are therefore hypothetical planning conventions and should not be treated as a description of the enrolled design.

Sample-size calculations estimate the amount of information a future study might need under specified assumptions. They do not show the probability that a completed study has established a finding. In particular, the planning illustrations are not observed power. The registry does not report the effect estimate used for them, and it does not report a sample-size justification for the actual study. Any numerical planning result would need to be understood as conditional on its stated assumptions, not as a result observed among participants.

What is known about the secondary outcome?

The secondary outcome concerns how precisely alpha, beta, delta, theta, gamma, and high-gamma neural activity frequencies predict participant speed on a cognitive task, with accuracy measured in percentage. This wording identifies the intended question but does not specify the statistical method, the performance measure’s analysis, or how prediction precision would be evaluated. The registry record does not report estimates, uncertainty, or results for this outcome. A predictive relationship, if analyzed, would be distinct from evidence that the microelectrode procedure changes task performance.

Overall, the methods information supports a description of the design and intended measures, but not a reconstruction of the analysis. The number of place-responsive neurons, participant-level data, analysis model, uncertainty estimates, and analysis population are not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 2 outcome measures and 0 analyses. It identifies a primary neuron-count endpoint and a secondary outcome concerning neural activity frequencies and cognitive-task performance. The record does not report a multiplicity strategy, such as how interpretation would account for evaluating more than one outcome or multiple frequency components. That plan is not reported in the registry record.

Missing-data procedures are also not reported. The record does not say whether any participants lacked endpoint measurements, how incomplete monitoring or unusable recordings were handled, or whether any imputation was planned or performed. The listed enrollment of 34 should not be taken as the number contributing to the primary endpoint: the analysis population and endpoint-specific denominator are not reported in the registry record.

The registry describes the primary population as patients with TLE undergoing intracranial EEG monitoring and implanted with depth electrodes and microelectrodes by the occipito-temporal approach. It does not provide a flow from enrollment to monitoring, recording, and analysis. There is no reported definition of an intention-to-treat, per-protocol, or other analysis population. In a single-group feasibility study, such details help clarify which participants and recordings contribute to the reported count, but they cannot be inferred from the enrollment field.

Without stated multiplicity, missing-data, and analysis-population procedures, the robustness of any outcome interpretation cannot be evaluated. No such result or analysis is reported in the registry record.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent serious adverse event terms

Serious events with the highest arm-level rate: infection (3.3%), chronic inflammatory reaction (3.3%).

The registry lists 30 at risk in the Microelectrodes group. In the serious adverse event field, 2 are listed as affected; the other adverse event field lists 0 affected, and deaths are listed as 0. Infection and chronic inflammatory reaction are each listed among the serious adverse event terms at 3.3%.

These entries should be read as registry safety fields, not as a comparison between groups: the study has a single-group design and no control arm. The record does not provide further details about event timing, severity beyond the serious classification, duration, or causal attribution to microelectrodes. The listed percentage for each serious term should be quoted as reported; the registry information does not explain the event-level counting or denominator conventions underlying those terms.

The safety counts do not answer the primary feasibility question about place-responsive neuron isolation. They are also not a full account of safety unless the registry’s event definitions, collection period, and completeness are understood. Those details are not reported in the registry record. The figures therefore describe the entries posted, without supporting a causal conclusion about the device or comparison with another monitoring approach.

12. What the Result Does, and Does Not, Mean

The study’s stated purpose is to test microelectrodes during intracranial monitoring for their ability to provide information about the epileptic potential of implanted brain tissue. The primary measure focuses more specifically on the number of place-responsive neurons isolated through the occipito-temporal implantation approach. A secondary objective concerns single-neuron activity during cognitive tasks. These aims make the study relevant to technical feasibility and the characterization of neural signals in the monitored setting.

The registry does not report the observed primary count, the secondary outcome results, or any analysis. It is therefore not possible to say from the posted record how many place-responsive neurons were isolated, how consistently they were observed across participants, or how well the listed frequency measures predicted task performance. The completed status and enrollment field do not substitute for outcome results.

Even if a count were available, the interpretation would depend on more than the total. Participant-level data and the number contributing to the endpoint would help show the consistency of the observations. Recording opportunity and variability would also be relevant to understanding a count outcome. These details are not reported in the registry record.

The single-group design does not provide a randomized comparison with standard electrodes alone or another control condition. Consequently, the record cannot establish a comparative advantage or isolate the effect of adding microelectrodes. The primary endpoint is a feasibility measure, not a measure of clinical benefit. No claim about seizure outcomes or patient health benefit follows from the endpoint description alone.

The safety entries list serious adverse events, other adverse events, and deaths, but do not include enough detail to attribute events to the device or compare safety with another approach. The appropriate reading is limited to the recorded counts and terms, alongside the substantial absence of outcome and analysis details.

13. Why This Trial Matters Statistically

This study raises several statistical issues that are common in early evaluations of recording technologies. Its primary outcome is a count of place-responsive neurons, while the stated purpose is feasibility. To understand feasibility, the total count is useful, but the distribution across participants and the number contributing recordings are also important. A large aggregate count can conceal variation in whether signals were found across individuals; a small count may reflect a low yield or limited observation opportunity. The registry does not report the data needed to distinguish these possibilities.

The single-group design also clarifies the scope of inference. It can describe what was recorded under the specified implantation approach, but it does not provide a randomized contrast against a comparator. This limits comparative interpretation independently of the sample size. A planning calculation for a hypothetical two-arm design cannot turn a single-group study into a controlled comparison.

Count outcomes call for attention to distribution and variability. General methods may need to accommodate over-dispersion if the data vary more than a simple count model expects. Reporting participant-level summaries and uncertainty would help readers judge how precise and reproducible the result may be. Neither the outcome result nor such analysis details are reported in the registry record.

The record also illustrates why registration details and results are distinct. It describes objectives, intervention, endpoint, enrollment, and status, but lists 0 analyses and does not report numerical outcome findings. A clearly stated question is not itself an answer to that question. The information available supports a careful description of the design and its statistical limitations, rather than a conclusion about feasibility or predictive performance.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The central limitation for interpreting this study from the registry record is that no numerical primary endpoint result or secondary-outcome analysis is reported. The number of place-responsive neurons, participant-level counts, uncertainty estimates, and analysis population are all absent. Without them, the stated feasibility question cannot be answered quantitatively.

The single-group design has no separate comparator, so it cannot provide a randomized estimate of the difference between microelectrodes and another monitoring approach. Masking is listed as none. The registry does not report a statistical analysis plan, a sample-size justification for the study, or procedures for missing data and multiplicity. These omissions limit assessment of the intended inference and the robustness of any result.

The population description is specific to patients undergoing intracranial EEG monitoring for TLE, with depth electrodes and microelectrodes placed by an occipito-temporal approach. Results from that setting, if available, would not automatically establish feasibility in other populations or with other implantation approaches. This is a general consideration about the scope of a study population, not a finding about performance in other settings.

The endpoint is a total count, but recording opportunity and participant-level variation are not reported. The stated monitoring period is approximately 2 weeks per patient, yet the record does not describe usable recording time or how differences in observation opportunity were handled. Finally, safety terms and counts are listed without details on timing, attribution, or event collection. These limitations mean that the registry supports description of the intended study and posted safety entries, but not a complete statistical evaluation of its outcomes.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Microelectrodes in Epilepsy — NCT05200455.
• Registry record last updated 2022-09-07; status last verified 2022-08.
• Results first posted 2022-09-07.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

NCT05200455 is a completed, single-group study titled “Microelectrodes in Epilepsy,” sponsored by Dartmouth-Hitchcock Medical Center. The condition is epilepsy; phase and allocation are listed as NA, and masking is listed as none. Enrollment is listed as 34, with start date 2009-09-18 and primary completion date 2021-03-30.

The primary endpoint is the number of place-responsive neurons isolated with microelectrodes through an occipito-temporal approach during intracranial monitoring. The secondary outcome concerns neural activity frequencies and cognitive-task performance. The registry lists 2 outcome measures and 0 analyses, but does not report numerical results for either outcome.

Safety fields list 2 affected in the serious adverse event category among 30 at risk, 0 affected in the other adverse event category, and 0 deaths. Infection and chronic inflammatory reaction are each listed at 3.3%. The record does not report a comparator, analysis population, missing-data approach, multiplicity plan, or uncertainty estimates.