ECT On-Line:Repetitive Transcranial Magnetic Stimulation (rTMS)

ECT ON LINE: Repetitive
Transcranial Magnetic Stimulation

It is a bit early to sell your ECT equipment - but rTMS is coming! As yet there is the beginning of a suggestion that it has useful antidepressive properties, and seemingly is very well tolerated in terms of side effects. It may not be as effective as ECT yet, and who knows how much a commercially distributed system will cost, and what degree of training will be required even to recruit sufficient numbers for good research? There seems to be a little confusion as to which pre-frontal cortex to stimulate... unless it is an artefact of using healthy volunteers. Only appear to be a few groups working on this at present?
At this stage, I will post some of the articles coming through in the scientific literature - and I'd appreciate pointers to useful ones that I miss.

Right frontal lobe slow frequency repetitive transcranial magnetic stimulation (SF r-TMS) is an effective treatment for depression: a case-control pilot study of safety and efficacy.
MENKESA DL, BODNARC P, BALLESTEROSB RA, SWENSONA MR (1999)
The J Neurol Neurosurg Psychiatry 1999;67:113-115

This paper makes a distinction between fast (FF r-TMS -stimulates cortex) and slow (SF r-TMS -inhibits cortical activity) frequency rTMS. Left frontat FF r-TMS appears to attenuate depression. This study looked at SF r-TMS to the right frontal lobe. 8 sessions of SR r-TMS were given right frontally over 6 weeks - at motor threshold. The Beck and Hamilton (Depression) scales both improved. No change occurred in controls suggesting an antidpressive effect with right frontal SF r-TMS.

Reduced cortical excitability in depression. Impaired post-excercise motor facilitation with transcrainial magnetic stimulation
SHAJAHAM PM, GLABUS MF, GOODING PA, SHAH PJ and EBMEIER KP (1999)
The British Journal of Psychiatry. 174.449-454.

More of a return to using TMS (Generally in the literature TMS refers to the study of individual stimuli- albeit given in trains, rTMS is the use of multiple repetitive stimuli as a therapeutic agent) as a research tool the authors are investigating the depressive symptom of fatigue and muscle weakness and its possible origin in the brain (rather than the muscle). TMS motor evoked potentials (MEP) increase in amplitude after some excecise but decrease once excercise has led to fatigue. Ten patients with major depressive episode and ten health controls had 50 baseline MEPs at 115% determined threashold. Further MEPs were elicited post excercise. Both groups reported equivalent fatigue. On repeated excercise and testing, the depressed group more quickly showed a response expected after excercise that caused fatigue. The authors consider that cortical interneurones rather than vertically running corticospinal neurones are selectively stimulated by TMS and suggest that depression is associated with reduced cortical excitability. (16 refs)

Transcranial Magnetic Stimulation: a treatment of the future?
SHAJAHAM P and EBMEIER K (1998)
Progress in Neurology and Psychiatry. 2,2,19-22.
An excellent introduction to rTMS covering some electrical/magnetic theory, evidence for safety of rTMS in humans , efficacy reports in depression, possible theories of mode of action and comparisons with ECT. rTMS can be stimulatory or inhibitory depending on the frequency of stimulations (lower=inhibit). Motor slowing in Parkinson's disease apparently may respond to rTMS. The stimulation level for a patient has to be calibrated for that patient using the minimum stiumulus intensity to get a predetermined electromyographic response. The authors caution that it is still a 'novel' treatment and further evaluation is required - one issue being how long treatment effects might last. rTMS may have even more variables to tease apart than ECT has.(22 refs and a photo)

Transcranial Magnetic Stimulation in Psychiatric Research.
PURI BK and LEWIS SW (1996)
The British Journal of Psychiatry. 169, 675-677.
The history behind stimulating human tissue with magnetism is summarised. TMS is painless, the currents induced in the brain are associated with energy levels perhaps a million times less than with ECT, and suggested to represent only 0.1% of the BMR of the brain itself. Seemingly, even metallic clips in the head pose no significant problem? TMS has been used diagnostically in a patient with 'presumed hysterical paraplegia' showing normal motor electrophysiology. Repetitive TMS (rTMS) may provide an alternative to ECT and work is ongoing with some good results in depression. (13 refs)

Safety of rapid-rate transcranial magnetic stimulation in normal volunteers.
PASCUAL-LEONE A. HOUSER CM. REESEK. SHOTLAND LI. GRAFMAN J. SATA S. VALLS-SOLE J. BRASIL-NETO JP. WASSERMANN EM. COHEN LG. et al. (1993)
Electroencephalography & Clinical Neurophysiology. 89(2):120-30
In 9 normal volunteers, the authors studied the safety of rapid-rate transcranial magnetic stimulation (rTMS) applied to different scalp positions at various frequencies and intensities, with no significant untoward effects.

Daily repetitive transcranial magnetic stimulation (rTMS) improves mood in depression.
GEORGE MS. WASSERMANN EM. WILLIAMS WA. CALLAHAN A. KETTER TA. BASSER P. HALLETT M. POST RM. (1995)
Neuroreport. 6(14):1853-6 Oct 2.
The authors report a pilot study of such treatment in six highly medication-resistant depressed inpatients. Depression scores significantly improved for the group as a whole. This involved Left prefrontal rTMS.

Changes in mood and hormone levels after rapid-rate transcranial magnetic stimulation (rTMS) of the prefrontal cortex.
GEORGE MS. WASSERMANN EM. WILLIAMS WA. STEPPEL J. PASCUAL-LEONE A. BASSER P. HALLETT M. POST RM. (1996)
Journal of Neuropsychiatry & Clinical Neurosciences. 8(2):172-80
rTMS in volunteers replicated a previous finding that Left pre-frontal rTMS lowered (self rated) mood, and Right pre-frontal rTMS decreased sadness.

Rapid-rate transcranial magnetic stimulation of left dorsolateral prefrontal cortex in drug-resistant depression
PASCUAL-LEONE A. RUBIO B. PALLARDO F. CATALA MD.(1996)
Lancet. 348(9022):233-7
Focal rTMS on psychotic depression. 17 medication resistance depressed patients in a randomised placebo cross-over using sham rTMS and other cortical areas. Left dorsolateral prefrontal cortex rTMS resulted in a significant decrease in scores on the Hamilton and Beck depression scales.

Use and safety of a new repetitive transcranial magnetic stimulator.
WASSERMANN EM. GRAFMAN J. BERRY C. HOLLNAGEL C. WILD K. CLARK K. HALLETT M (1996)
Electroencephalography & Clinical Neurophysiology. 101(5):412-7
The authors administered transcranial magnetic stimulation (TMS) at 1 Hz and 125% of motor threshold for an average of 204 s (until the coil temperature reached 40 degrees C) and 20 Hz stimulation at 100% of motor threshold for 2 s every minute for 10 min, on different days to 10 healthy volunteers. A range of evaluations were made, and the conclusions that the rTMS used was 'safe'. It is clear however that rTMS appears to introduce perhaps an order of magnitude increase in variables - if we found ECT hard to standardise....

Lateralized effect of rapid-rate transcranial magnetic stimulation of the prefrontal cortex on mood.
PASCUAL-LEONE A. CATALA MD. (1996)
Neurology. 46(2):499-502
10 volunteers self rated (visual analog scales) sadness anxiety, happiness, tiredness, pain/discomfort. Right-lateral prefrontal, Left pre-frontal or Midline frontal trains of rTMS were applied for 5 seconds' duration at 10 Hz and 110% of the subject's motor threshold intensity. Again Left prefrontal stimulation increased sadness.

Bridging the skull: electroconvulsive therapy (ECT) and repetitive transcranial magnetic stimulation (rTMS) in psychiatry.
KIRKALDIE M. PRIDMORE S. REID P.(1997)
Convulsive Therapy. 13(2):83-91
Similarities and differences between ECT and rTMS. Magnetic fields penetrate further and can stimulate more specifically. rTMS does not require an anaesthetic and doesn't alter memory. (55 Refs)

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Carl S. Littlejohns MB,ChB MRCPsych
carl_mail@dr.com

Psychiatry On
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