How to Administer and Monitor Left DLPFC iTBS in Schizophrenia
How was the experimental left DLPFC iTBS course delivered and monitored for patients with schizophrenia and predominant negative symptoms?
When clinicians or researchers consider applying this experimental neuromodulation protocol, the practical details of targeting, session structure, and monitoring matter. This guide summarizes exactly how the study delivered and followed a high-density iTBS course in schizophrenia with chronic negative symptoms.
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Complete baseline symptom assessment
Before starting stimulation, assess patients with the MINI, SANS, SAPS, Calgary Depression Scale for Schizophrenia, and Clinical Global Impression. The study used these baseline measures to characterize psychiatric status and to track change after treatment and during follow-up.
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Determine motor threshold and localize the target
Begin each treatment session with motor threshold determination. Localize the stimulation site 5.5 cm anterior and 0.5 cm lateral to the motor cortex, and identify resting motor threshold by recording motor evoked potentials from the hand area of M1.
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Deliver the study iTBS protocol
Apply iTBS to the left DLPFC at 100% of the individual motor threshold. The protocol used 720 pulses per session in 8 trains of 90 pulses, with each session lasting 5 minutes 52 seconds; intertrain intervals were extended to prevent coil overheating and reduce discomfort.
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Schedule the full treatment course
Administer sessions 5 days per week for 3 weeks, for a total of 15 sessions. The authors limited treatment to 15 sessions because prior experience suggested dropout rates increased significantly beyond this point due to difficulty attending daily.
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Continue antipsychotics and document concurrent treatment
Maintain prescribed antipsychotic medications during the intervention and record them. The study notes that concurrent treatments, including occasional benzodiazepine use and later medication adjustments, can confound interpretation of response and may affect iTBS efficacy.
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Monitor weekly and track adverse effects closely
Conduct weekly follow-ups in the TMS clinic during treatment and watch for local adverse effects, headache, fatigue, sleepiness, insomnia, and worsening aggression. In this trial, local adverse effects were more common with active stimulation than sham, fatigue and sleepiness occurred only in the active group, and 1 active-treatment patient stopped after worsening aggression and insomnia.
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Reassess after treatment and through 6 months
Repeat the same rating tools immediately after intervention and again at 1-, 2-, 3-, 4-, 5-, and 6-month follow-ups. The study found that both active and sham groups improved over time, but active treatment did not separate from sham at any follow-up point.
Clinical Considerations
- This was a nonstandard high-density iTBS protocol, so it should not be assumed equivalent to more common protocols using 600 pulses per session and 20 or more sessions.
- Protocol modifications intended to improve tolerability, including longer intertrain intervals and fewer total sessions, may have reduced neuroplastic efficacy.
- The study found no superiority of active iTBS over sham despite the structured treatment and follow-up schedule.
- Blinding integrity and participant expectancy were not formally assessed, which may have contributed to placebo-related improvement in both groups.
Bottom Line
If this experimental left DLPFC iTBS protocol is used, replicate the study's targeting, dosing, schedule, and follow-up closely, but counsel that it did not outperform sham and requires active monitoring for mild adverse effects and occasional behavioral or sleep worsening.
