Bilateral rTMS after failure of unilateral protocol in TRD w/ mixed features — mechanism, expectations & cognitive effects?

Hi all,

I’m a 20M currently undergoing a course of sequential bilateral rTMS for treatment-resistant depression with mixed features and comorbid OCD.

I previously completed a full course of unilateral left DLPFC (10 Hz) rTMS without response. I’ve also had trials of multiple pharmacotherapies and ECT.

My current course involves:

inhibitory stimulation of the right DLPFC

excitatory stimulation of the left DLPFC

Planned reassessment is at session 15 (I’m currently at session 7).

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Questions:

1. Bilateral vs Unilateral

Mechanistically, how does sequential bilateral stimulation (R inhibitory + L excitatory) differ from classic unilateral left DLPFC protocols?

In patients with:

agitation

rumination

possible mixed features

is targeting both hemispheres thought to improve outcomes compared to left-sided stimulation alone?

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2. Theta Burst Stimulation

Could someone explain in simple terms:

What iTBS vs cTBS actually do at the network level?

How do these differ from traditional 10 Hz stimulation?

Why might inhibitory right-sided TBS be paired with excitatory left-sided stimulation?

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3. Mid-Course Variability

Is it typical to see:

day-to-day mood variability

sleep changes

emotional lability

in the first 1–2 weeks of bilateral protocols before improvement emerges?

At what session number would you usually:

expect early response

consider modifying protocol if no change?

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4. Cognitive Effects

Are transient complaints such as:

word-finding difficulty

slowed processing

“brain fog”

reported during early rTMS courses?

Or are these more likely attributable to:

concurrent sedating medications

sleep disruption

illness severity?

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Any input from clinicians or technicians familiar with bilateral or TBS protocols in complex TRD presentations would be much appreciated.

Thanks!