The current study aims to better understand the efficacy of intermittent theta-burst stimulation (iTBS) treatment in patients diagnosed with post-concussion syndrome (PCS) and to explore changes in brain networks after undergoing iTBS to assess its safety and feasibility in treating PCS.

This open-label pilot study aims to investigate the potential of a non-invasive brain stimulation technique, accelerated intermittent theta-burst stimulation (iTBS) repetitive transcranial magnetic stimulation (rTMS), for treating post- concussive syndrome (PCS) in persons with mild traumatic brain injury (mTBI). PCS is characterized by symptoms like cognitive impairment, mood dysregulation, fatigue, and headaches, with limited treatment options. Previous research has indicated brain network dysfunction in mTBI patients and suggested the potential of conventional once daily high frequency rTMS for treating PCS symptoms. Our proposal builds on these findings by utilizing the expertise and resources of Sunnybrook's Harquail Centre for Neuromodulation, which has extensive experience in delivering rTMS and theta-burst stimulation for treatment-resistant depression. This pilot study will implement an accelerated iTBS rTMS protocol, offering shorter treatment duration, as well as MRI-guided stimulation for precise targeting. The investigators will also explore changes in brain function following rTMS using a technique called functional magnetic resonance imaging. The investigators ultimately aim to understand how iTBS may alter the post-concussive brain and the extent to which these changes may improve PCS.

Inclusion Criteria:

• Documented evidence of head trauma sufficiently severe to result in loss of consciousness, post-traumatic amnesia and/or acute altered mental status.
• At least three symptoms including headache, dizziness, fatigue, irritability, insomnia, memory difficulties, concentration difficulties, mood dysregulation.
• Onset of symptoms within 4 weeks following the head trauma.
• Age 18-60, inclusive.
• Persistence of PCS symptoms for at least 3 months but less than 24 months
• Able to provide informed consent and comply with the study protocol
• Patients will not be excluded solely on the basis of communication (i.e., non-English speaking) unless they have exclusion criteria that is the cause of the communication difficulties.

Exclusion Criteria:

• Evidence of major structural neuroimaging abnormalities (e.g., intracranial hemorrhage, skull fracture or a large intracranial lesion)
• History of prior rTMS therapy,
• Contraindications to MRI (e.g., pacemaker, metallic implants etc.).
• Ferromagnetic, non-removable metallic implants from above the clavicle with the exception of dental work.
• Active personal injury litigation
• History of seizure disorder, not including febrile seizures in childhood
• Substance dependence within the last 6 months
• Pregnant
• Currently taking more than lorazepam 2 mg daily (or benzodiazepine equivalent) or any dose of an anticonvulsant (due to the potential to reduce rTMS efficacy)
• Currently taking an antiepileptic medication
• Mild and major comorbid medical conditions (as determined by investigators - e.g., neurological diseases, uncontrolled hypertension or diabetes, malignancy)
• A major comorbid psychiatric disorder (as determined by investigators - e.g., schizophrenia or bipolar disorder) and/or psychosis at the time of study enrollment.