The contribution of transcranial magnetic stimulation in the diagnosis and in the management of dementia.
Transcranial magnetic stimulation (TMS) is emerging as a promising tool to non-invasively assess specific cortical circuits in neurological diseases. A number of studies have reported the abnormalities in TMS assays of cortical function in dementias. A PubMed-based literature review on TMS studies targeting primary and secondary dementia has been conducted using the key words "transcranial magnetic stimulation" or "motor cortex excitability" and "dementia" or "cognitive impairment" or "memory impairment" or "memory decline". Cortical excitability is increased in Alzheimer's disease (AD) and in vascular dementia (VaD), generally reduced in secondary dementias. Short-latency afferent inhibition (SAI), a measure of central cholinergic circuitry, is normal in VaD and in frontotemporal dementia (FTD), but suppressed in AD. In mild cognitive impairment, abnormal SAI may predict the progression to AD. No change in cortical excitability has been observed in FTD, in Parkinson's dementia and in dementia with Lewy bodies. Short-interval intracortical inhibition and controlateral silent period (cSP), two measures of gabaergic cortical inhibition, are abnormal in most dementias associated with parkinsonian symptoms. Ipsilateral silent period (iSP), which is dependent on integrity of the corpus callosum is abnormal in AD. While single TMS measure owns low specificity, a panel of measures can support the clinical diagnosis, predict progression and possibly identify earlier the "brain at risk". In dementias, TMS can be also exploited to select and evaluate the responders to specific drugs and, it might become a rehabilitative tool, in the attempt to restore impaired brain plasticity.
Institute of Neurology, Campus Bio-Medico University, Via Álvaro del Portillo 200, 00128 Rome, Italy.
Mariagiovanna
M
Cantone
Institute of Neurology, Campus Bio-Medico University, Via Álvaro del Portillo 200, 00128 Rome, Italy; Fondazione Alberto Sordi - Research Institute for Ageing, Via Álvaro del Portillo 5, 00128 Rome, Italy.
Giovanni
G
Di Pino
Institute of Neurology, Campus Bio-Medico University, Via Álvaro del Portillo 200, 00128 Rome, Italy; Fondazione Alberto Sordi - Research Institute for Ageing, Via Álvaro del Portillo 5, 00128 Rome, Italy.
Fioravante
F
Capone
Institute of Neurology, Campus Bio-Medico University, Via Álvaro del Portillo 200, 00128 Rome, Italy; Fondazione Alberto Sordi - Research Institute for Ageing, Via Álvaro del Portillo 5, 00128 Rome, Italy.
Marianna
M
Piombo
Institute of Neurology, Campus Bio-Medico University, Via Álvaro del Portillo 200, 00128 Rome, Italy; Fondazione Alberto Sordi - Research Institute for Ageing, Via Álvaro del Portillo 5, 00128 Rome, Italy.
Daniela
D
Chiarello
Nuffield Department of Clinical Neurosciences, University of Oxford, Level 6, West Wing, John Radcliffe Hospital, Oxford OX3 9DU, UK.
Binith
B
Cheeran
Department "G.F. Ingrassia", Section of Neurosciences, University of Catania, Via Santa Sofia, 78-95123 Catania, Italy.
Giovanni
G
Pennisi
Institute of Neurology, Campus Bio-Medico University, Via Álvaro del Portillo 200, 00128 Rome, Italy; Fondazione Alberto Sordi - Research Institute for Ageing, Via Álvaro del Portillo 5, 00128 Rome, Italy. Electronic address: v.dilazzaro@unicampus.it.
Vincenzo
V
Di Lazzaro
D000109:Acetylcholine / Q000378:metabolism; D000544:Alzheimer Disease / Q000175:diagnosis / Q000378:metabolism / Q000628:therapy; D002540:Cerebral Cortex / Q000378:metabolism; D060825:Cognitive Dysfunction / Q000175:diagnosis* / Q000209:etiology / Q000378:metabolism / Q000628:therapy*; D003704:Dementia / Q000150:complications / Q000175:diagnosis* / Q000378:metabolism / Q000628:therapy*; D015140:Dementia, Vascular / Q000175:diagnosis / Q000378:metabolism / Q000628:therapy; D003937:Diagnosis, Differential; D057180:Frontotemporal Dementia / Q000175:diagnosis / Q000378:metabolism / Q000628:therapy; D006801:Humans; D020961:Lewy Body Disease / Q000175:diagnosis / Q000378:metabolism / Q000628:therapy; D019578:Multiple System Atrophy / Q000175:diagnosis / Q000378:metabolism / Q000628:therapy; D009473:Neuronal Plasticity; D010300:Parkinson Disease / Q000175:diagnosis / Q000378:metabolism / Q000628:therapy; D017981:Receptors, Neurotransmitter / Q000378:metabolism; D013494:Supranuclear Palsy, Progressive / Q000175:diagnosis / Q000378:metabolism / Q000628:therapy; D050781:Transcranial Magnetic Stimulation / Q000379:methods*
D017981:Receptors, Neurotransmitter; D000109:Acetylcholine
Brain stimulation; Cognitive dysfunction; Cortical excitability; Differential diagnosis; Intracortical circuitry; Motor impairment; Neuromodulation