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Clinical Neuroscience

DECEMBER 10, 2005

[TRANSCRANIAL MAGNETIC STIMULATION: PHYSIOLOGY AND APPLICATIONS]

ARÁNYI Zsuzsanna

[Transcranial magnetic stimulation (TMS) is a relatively new technique that allows painless activation of cortical motor neurons. In the clinical setting, TMS is primarily used for the investigation of the corticospinal tract in various neurological diseases, being especially useful in the detection of subclinical dysfunction. In addition to the motor cortex, TMS can be applied to examine other structures inaccessible to electrical stimulation, such as the canalicular portion of the facial nerve. In healthy individuals, TMS can be utilized to monitor excitability changes of the motor system in various situations and muscles, providing valuable information to the understanding of the physiology of motor control. Furthermore, TMS can be used to explore interhemispheric connections as well as intracortical inhibitory and excitatory processes both in health and disease. Finally, with the help of TMS cortical maps of the representation areas of muscles can be constructed, giving insight to both short and long-term cortical plasticity and to the reorganisation of the motor cortex following damage to the brain or acquisition of new motor skills]

Clinical Neuroscience

DECEMBER 20, 2002

[The role of transcranial magnetic stimulation in clinical diagnosis: facial nerve neurography]

ARÁNYI Zsuzsanna, SIMÓ Magdolna

[Facial nerve neurography involving magnetic stimulation techniques can be used to assess the intracranial segment of the facial nerve and the entire facial motor pathway, as opposed to the traditional neurography, involving only extracranial electric stimulation of the nerve. Both our own experience and data published in the literature underline the value of the method in localising facial nerve dysfunction and its role in clinical diagnosis. It is non-invasive and easy to perform. Canalicular hypoexcitability has proved to be the most useful and sensitive parameter, which indicates the dysfunction of the nerve between the brain stem and the facial canal. This is an electrophysiological finding which offers for the first time positive criteria for the diagnosis of Bell’s palsy. The absence of canalicular hypoexcitability practically excludes the possibility of Bell’s palsy. The technique is also able to demonstrate subclinical dysfunction of the nerve, which can be of considerable help in the etiological diagnosis of facial palsies. For example, in a situation where clinically unilateral facial weakness is observed, but facial nerve neurography demonstrates bilateral involvement, etiologies other than Bell’s palsy are more likely, such as Lyme’s disease, Guillain-Barré syndrome, meningeal affections etc. Furthermore, the technique differentiates reliably between peripheral facial nerve lesion involving the segment in the brain stem or the segment after leaving the brainstem.]