TMS and Attentional Bias in Functional Motor Disorder

A randomised non-blinded controlled study design will be used, with 3 months of treatment as usual as the control condition and a single session of TMS as the treatment condition.

40 patients with functional unilateral upper limb weakness will be recruited from neurology and neuropsychiatry clinics in Edinburgh and randomised to either immediate treatment or to 3 month delay during which they will receive routine clinical care. Randomisation will be performed using computerised random number generator by a person not involved with the study.

Patients randomised to delay will complete baseline measures of disability and motor function including SF36, modified Rankin score and study specific questionnaires, and will repeat these after 3 months. Patients undergoing immediate treatment will complete the same questionnaires immediately before and 3 months after treatment. All individuals receiving TMS treatment will undergo tests of grip strength and tapping frequency immediately before and after treatment.

The treatment and experiments involved will be as follows. Patients will attend the PPLS Cognitive Neuroscience Laboratory at George Square, University of Edinburgh for a single 2 hour session. During the first hour they will complete baseline symptom severity and disability questionnaires and will undertake a series of 3 experiments. Experiments involve participants sitting with their head on a chin-rest looking at either a computer screen or at lights projected onto their own hands, and for one experiment with a vibrating 'buzzer' taped to each hand. They will be asked to respond verbally in experiments which test their response to distracting attentional 'cues' either visual or vibrotactile. These experiments will take less than 1 hour. In anaylsis, performance will be compared between affected and unaffected sides (ie left hand and right hand), and will also be compared with performance of a group of 15 healthy control participants recruited from spouses or partners.

Patient participants will then receive treatment with 20 single pulses of TMS to the motor cortex at 120% motor threshold. These will cause visible and palpable 'jerks' of the affected limb. Between stimulations the researcher will offer verbal encouragement and ask the participant to move the affected limb if possible. Treatment will take less than 1 hour.

The primary outcome measures are patient-rated symptom severity and disability and simple statistical analysis will be used to compare outcome after 3 months of treatment as normal and 3 months after a single session of TMS treatment. Secondary outcome measures include grip strength and tapping frequency before and after treatment. Data will be analysed on an intention-to-treat basis. Data from attentional tests will be analysed separately.

Inclusion criteria

• clinical diagnosis, by a consultant neurologist, of functional motor disorder
• functional unilateral upper limb weakness present for 50% or more of the time
• age 18-75
• ability to give informed consent

Exclusion criteria

• difficulties in understanding spoken or written English
• history of epileptic seizures (non-epileptic seizures will not be an exclusion criteria)
• alcohol dependence
• severe co-morbid physical or psychiatric disorder
• factitious disorder
• patients unable to receive TMS because of metal implants such as pacemakers