Alternating magnetic field induces the electrical current in the conductor

In general magnetic stimulator consists of capacitor, coil and switch

Types of Coils

Electric field intensity induced below the coils of different types

Magnetic Induction Decrement with Distance

– Small coils have stronger field on the surface but field decreases dramatically with distance. Therefore small coils are suitable for peripheral stimulation in which magnetic field does not need to pass through skull bones

– Big coils have lower decrease of field with distance. Therefore they are used for transcranial stimulation

– Ring coils are less focused. Therefore they are used for stimulation of wide areas (for diagnostics)

– Figure-of-eight coils are more focused, therefore they are widely used for treatment

General Rules for Selecting the Appropriate Coil for Certain Application

How TMS Works

Motor Evoked Potential (MEP) Generation

General Peculiarities of MEP:

– Amplitude is always lower than amplitude of response recoded from same muscle with supramaximal electrical stimulation of peripherial nerve

– Amplitude is variable, but we can speak about steady level

We believe that MEP amplitude reflects the quantity of motor neurons ready for excitation at the moment of stimulation

MEP amplitude = cortex excitability

Variation of MEP amplitude = variation of cortex excitability

Facilitation

Motor Evoked Potential Emergence at Arbitrary Muscle Tension Spinal Column Trauma)

Silent Period (SP)

IHI (Interhemispheric Inhibition)

Time, min

MEP variation within 16 minutes after 5 Hz stimulation of motor cortex

LTP (Long-term Penetration)

– We can excite activity (facilitation)

– We can inhibit activity (silent period)

– We can stimulate one site but get inhibition at another site (interhemispheric inhibition)

– We can have long-term post-stimulation effect (long-term penetration)

How We Can Use TMS for Brain Activity Modulation

Daily Practical Use: Diagnostics

Central Motor Conduction Time (CMCT)

Diagnostic TMS Use

Main Techniques:

– Amplitude of motor evoked potential (MEP)

– Amplitude ratio (motor evoked potential/M-wave)

– Motor evoked potential facilitation

– Central motor conduction time

– Triple stimulation testDiagnostic Areas:

– Stroke patients

– Spinal and brain trauma

– Parkinson’s disease

Daily Practical Use: Therapeutic

Therapeutic TMS Use

Amblyopia[11][12] Amyotrophic lateral sclerosis Auditory hallucinations associated with schizoaffective disorders Chronic pain Dysphasia Dystonia Epilepsy Fibromyalgia Hemispatial neglect Major depression Migraine[13] Obsessive-compulsive disorder Parkinson’s disease Phantom limb Stroke Nonfluent aphasia [14] Tinnitus[15]

TMS Use to Treat Depressions

Is TMS Safe?

When user follows Internationally recognized safety guidelines, TMS is safe

TMS is not recommended for children, pregnant women, patients with implants and patients with epilepsy

“Risk and safety of repetitive transcranial magnetic stimulation: report and suggested guidelines from the International Workshop on the safety of repetitive magnetic stimulation, June 5-7. 1996” by Eric M. Wassermann (accepted for publication: 23 May 1997)

Motor Threshold (MT)

Minimum intensity required to elicit a small motor evoked potential in at least half of the trials

It may be expected that motor threshold depends on the excitability of those elements which are activated by TMS

For treatment purposes MT level means intensity of stimulation just enough to excite cortex

Stimulation with lower intensities might not be effective and stimulation with higher intensities can be uncomfortable

Stimulation Point and Coil Orientation in Depression Treatment

Treatment Workflow

1. Prepare a patient2. Determine the MT at MT detection point3. Move coil to stimulation point4. Set stimulation parameters5. Run test and observe the patient during the stimulation6. Make a record

Protocols for Depression Treatment

The majority of our customers apply Neuro-MS to treat depression using these protocols:

Over the left frontal dorsolateral cortex (5 cm anterior (parallel to the sagittal line) to the area where the motor threshold is obtained)5 Hz, 25 trains of 10 seconds each with 20-second pause between the trains. Applied at 120% of the motor threshold (protocol used by Dr. Marcolin).

or

10 Hz, 30 trains of 4 seconds each with 20-second pause between the trains. Applied at 100% of the motor threshold (or 120%, when possible - limited by the power of the device) (protocol used by Dr. Moacyr).

The quantity of stimuli for effective treatment is considered as more than 1000 pulses

Number of sessions: 15-30 (3-6 weeks)

Video 2

What is Cooling System for?In total 1250 pulses at 120% of MT or 1200 pulses at 100 % of MT for depression treatment.

The vast majority of patients have MT at about 40-60% of MO (maximum output of Neuro-MS).

It means they need to be stimulated at 40-72% of MO.

Neuro-MS coil is equipped with built-in temperature sensor which stops the device when coil temperature reaches 41 C and over. In average coil gets overheated after 250 pulses at 5 Hz at maximum intensity.

It means that without cooling system Neuro-MS is able to perform standard depression treatment only if we change the coil during the session at least once.

With cooling system practically there are no limitation on duration of treatment session.

Stimulation Frequency

Maximum intensity drops with frequency increase

If we consider 72% to be the most wide-spread intensity for stimulation of patients with depressions then maximum achieved frequency is 10 Hz

We will name this term “effective frequency”

What is Placebo-coil for?

Placebo coil should:

– Look like normal one

– Produce click like normal one

– But generate low-intensity stimulus

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