A Review of Transcranial Magnetic Stimulation in the in vivo Functional Evaluation of Central Cholinergic Circuits in Dementia

Nardone, Raffaele; Golaszewski, Stefan; Ladurner, G.; Tezzon, Frediano; Trinka, Eugen

doi:10.1159/000330016

Cited by 26 publications

(17 citation statements)

References 129 publications

(94 reference statements)

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“…SAI is reduced in cholinergic forms of dementia, while it is normal in non-cholinergic forms of dementia [18]. The amount of SAI was found to be decreased in patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy and cognitive impairment [19].…”

Section: Introductionmentioning

confidence: 94%

Abnormal Corticospinal Excitability in Patients with Disorders of Consciousness

et al. 2013

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Keywords:Vegetative state Unresponsive wakefulness syndrome Minimally conscious state Brain injury Transcranial magnetic stimulation Motor evoked potentials Somatosensory evoked potentials Short latency afferent inhibition a b s t r a c t Background: Transcranial magnetic stimulation (TMS) has been frequently used to explore changes in the human motor cortex in different conditions, while the extent of motor cortex reorganization in patients in vegetative state (VS) (now known as unresponsive wakefulness syndrome, UWS) and minimally conscious (MCS) states due to severe brain damage remains largely unknown. Objective/hypothesis: It was hypothesized that cortical motor excitability would be decreased and would correlate to the level of consciousness in patients with disorders of consciousness. Methods: Corticospinal excitability was assessed in 47 patients (24 VS/UWS and 23 MCS) and 14 healthy controls. The test parameters included maximal peak-to-peak M-wave (M max ), F-wave persistence, peripheral and central motor conduction times, sensory (SEP) and motor evoked (MEP) potential latencies and amplitudes, resting motor threshold (RMT), stimulus/response curves, and short latency afferent inhibition (SAI). TMS measurements were correlated to the level of consciousness (assessed using the Coma Recovery Scale-Revised). Results: On average, the patient group had lower M max , lower MEP and SEP amplitudes, higher RMTs, narrower stimulus/response curves, and reduced SAI compared to the healthy controls (P < 0.05). The SAI alterations were correlated to the level of consciousness (P < 0.05). Conclusions:The findings demonstrated the impairment of the cortical inhibitory circuits in patients with disorders of consciousness. Moreover, the significant relationship was found between cortical inhibition and clinical consciousness dysfunction.Ó 2013 Elsevier Inc. All rights reserved. IntroductionFollowing severe brain damage, disorders of consciousness (DOC), such as vegetative state (VS) (now known as unresponsive wakefulness syndrome, UWS) [1] or minimally conscious state (MCS) have been linked to poor long term prognosis [2]. The recovery of consciousness could be related to the number of surviving neurons and the functional integrity of long-range cortico-cortical and cortico-thalamo-cortical connections [3]. Transcranial magnetic stimulation (TMS) is an objective method to assess the motor cortex excitability and the integrity of motor pathways [4]. Several studies indicate that cortical injuries, independent of their etiology, can lead to a reduced strength of inhibitory neurotransmission [5e8]. Paired TMS has been used for over 20 years to investigate recovery of motor function in stroke patients [9]. Cortical excitability is also shown to correlate with the severity of brain damage in patients with diffuse traumatic brain injury (TBI) [10e14] and to be related to the clinical recovery in mild to moderate TBI [15]. By coupling peripheral nerve stimulation with TMS, it is possible to modify the excitability of the mot...

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Section: Introductionmentioning

confidence: 94%

Abnormal Corticospinal Excitability in Patients with Disorders of Consciousness

et al. 2013

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“…In a recent paper aiming at the evaluation of short-latency afferent inhibition in a sample of VCI-ND patients with predominant WMLs, central cholinergic circuitry was found to be not clearly involved in patients compared to age-matched controls [95], suggesting a distinctive profile of the cholinergic pathway with respect to primary cholinergic forms of dementia (namely, AD), even in the early stage [99]. A reasonable explanation is that VCI may exhibit considerable interindividual variation in the location of subcortical infarcts and, therefore, in the distribution and magnitude of the resultant cholinergic denervation [100]. This study also supports the role of short-latency afferent inhibition in providing useful insight in the diagnosis and prognosis of different dementing process and in the identification of responders to acetylcholinesterase inhibitors [95].…”

Section: Tms Correlates Of Vci Subtypesmentioning

confidence: 99%

Vascular Cognitive Impairment through the Looking Glass of Transcranial Magnetic Stimulation

Lanza¹,

Bramantı

Cantone³

et al. 2017

Behavioural Neurology

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In the last years, there has been a significant growth in the literature exploiting transcranial magnetic stimulation (TMS) with the aim at gaining further insights into the electrophysiological and neurochemical basis underlying vascular cognitive impairment (VCI). Overall, TMS points at enhanced brain cortical excitability and synaptic plasticity in VCI, especially in patients with overt dementia, and neurophysiological changes seem to correlate with disease process and progress. These findings have been interpreted as part of a glutamate-mediated compensatory effect in response to vascular lesions. Although a single TMS parameter owns low specificity, a panel of measures can support the VCI diagnosis, predict progression, and possibly identify early markers of “brain at risk” for future dementia, thus making VCI a potentially preventable cause of both vascular and degenerative dementia in late life. Moreover, TMS can be also exploited to select and evaluate the responders to specific drugs, as well as to become an innovative rehabilitative tool in the attempt to restore impaired neural plasticity. The present review provides a perspective of the different TMS techniques by further understanding the cortical electrophysiology and the role of distinctive neurotransmission pathways and networks involved in the pathogenesis and pathophysiology of VCI and its subtypes.

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“…[6] The threshold of motor response is an index of excitability of the corticospinal motor neurons and the amplitude of the motor response and duration of silent period (SP) is related to cortical inhibition mediated through gamma-aminobutyric acid (GABA)-B receptors. Using a study performed in fifteen patients with a single pulse stimulation the authors found the following changes in Alzheimer's disease using the short-latency afferent inhibition (SAI), which is produced by inhibitory interactions within the cerebral cortex.…”

Section: Introductionmentioning

confidence: 99%

Transcranial magnetic stimulation in patients with early cortical dementia: A pilot study

Issac

Chandra

Nagaraju

2013

Ann Indian Acad Neurol

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Context:The diagnostic accuracy of the currently available tools carries poor sensitivity resulting in significant delay in specific diagnosis of cortical dementias. Considering the properties of default mode networking of the brain it is highly probable that specific changes may be seen in frontotemporal dementias (FTDs) and Alzheimer's disease sufficiently early.Aim:The aim of this study is to look for changes in Transcranial Magnetic Stimulation (TMS) in cortical dementia.Materials and Methods:Evaluated with a single pulse TMS with the figure of eight coil and recorded from right first dorsal interossei (FDI). Resting Motor Threshold (RMT) was estimated on the opposite motor cortex (T1). Second site of stimulation was cervical spine at C7-T2. Central motor conduction time (CMCT) is equal toT1-T2. Silent Period (SP) identified by applying TMS pulse to contracting FDI.Conclusions:RMT was reduced in seven out of eight Alzheimer's dementias. CMCT was in the upper limit of normal in both patients with FTD. The most consistent observation was that SP was reduced and there were escape discharges noticed during the SP suggesting increased cortical excitability and decreased cortical inhibition. This suggests probable early asymptomatic changes in the gamma-aminobutyric acid (GABA) nergic and cholinergic system is taking place. This if confirmed may give some insight into early diagnosis and therapeutic role of GABA agonists in these disorders.

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A Review of Transcranial Magnetic Stimulation in the in vivo Functional Evaluation of Central Cholinergic Circuits in Dementia

Cited by 26 publications

References 129 publications

Abnormal Corticospinal Excitability in Patients with Disorders of Consciousness

Abnormal Corticospinal Excitability in Patients with Disorders of Consciousness

Vascular Cognitive Impairment through the Looking Glass of Transcranial Magnetic Stimulation

Transcranial magnetic stimulation in patients with early cortical dementia: A pilot study

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