Magnetoencephalographic study of hand and foot sensorimotor organization in 325 consecutive patients evaluated for tumor or epilepsy surgery

Abstract

ObjectivesThe presence of intracranial lesions or epilepsy may lead to functional reorganization and hemispheric lateralization. We applied a clinical magnetoencephalography (MEG) protocol for the localization of the contralateral and ipsilateral S1 and M1 of the foot and hand in patients with non-lesional epilepsy, stroke, developmental brain injury, traumatic brain injury and brain tumors. We investigated whether differences in activation patterns could be related to underlying pathology.MethodsUsing dipole fitting, we localized the sources underlying sensory and motor evoked magnetic fields (SEFs and MEFs) of both hands and feet following unilateral stimulation of the median nerve (MN) and posterior tibial nerve (PTN) in 325 consecutive patients. The primary motor cortex was localized using beamforming following a self-paced repetitive motor task for each hand and foot.ResultsThe success rate for motor and sensory localization for the feet was significantly lower than for the hands (motor_hand 94.6% versus motor_feet 81.8%, p < 0.001; sensory_hand 95.3% versus sensory_feet 76.0%, p < 0.001). MN and PTN stimulation activated 86.6% in the contralateral S1, with ipsilateral activation < 0.5%. Motor cortex activation localized contralaterally in 76.1% (5.2% ipsilateral, 7.6% bilateral and 11.1% failures) of all motor MEG recordings. The ipsilateral motor responses were found in 43 (14%) out of 308 patients with motor recordings (range: 8.3–50%, depending on the underlying pathology), and had a higher occurrence in the foot than in the hand (motor_foot 44.8% versus motor_hand 29.6%, p = 0.031). Ipsilateral motor responses tended to be more frequent in patients with a history of stroke, traumatic brain injury (TBI) or developmental brain lesions (p = 0.063).ConclusionsMEG localization of sensorimotor cortex activation was more successful for the hand compared to the foot. In patients with neural lesions, there were signs of brain reorganization as measured by more frequent ipsilateral motor cortical activation of the foot in addition to the traditional sensory and motor activation patterns in the contralateral hemisphere. The presence of ipsilateral neural reorganization, especially around the foot motor area, suggests that careful mapping of the hand and foot in both contralateral and ipsilateral hemispheres prior to surgery might minimize postoperative deficits.

Motor Cortical Network Plasticity in Patients With Recurrent Brain Tumors

“…The whole-brain activation maps detected motor activations in the contralateral MC (ipsilateral to active finger) as well. This has been already described in healthy individuals and patients with various intracerebral lesions during a motor task (Taniguchi et al, 2000(Taniguchi et al, , 2004Nagarajan et al, 2008;Willemse et al, 2010Willemse et al, , 2016. Since ipsilateral MC activation has been demonstrated in healthy participants, it likely occurs with some frequency in the normal population.…”

Presurgical electromagnetic functional brain mapping in refractory focal epilepsy

“…Several MEG methods have been validated to localize the SM1 cortex and are summarize in Table 1. These are electrical peripheral nerve stimulation [12,17,42,43,52,82,90,92,94], tactile stimulation [72,76], readiness and motor evoked fields [29,38,42,47,94], rolandic mu rhythm desynchronization/suppression (alpha or beta band components) [12,55,93,94] or cortico-muscular coherence (CMC) [12,52].…”

A new model of experimental hemispherotomy in young adult Rattus norvegicus: a neural tract tracing and SPECT in vivo study

“…Experimental neurological approaches investigate the complex neurobiological mechanisms involved in epileptogenesis and the maintenance of seizures, 25 the development of new antiepileptic drugs, 9,18,20 alterations in synaptic plasticity, 26,50 the neurophysiological and neuropharmacological bases of the postictal immobility syndrome, 8,12 the characteristics of ictal and postictal states, 31 and postsurgical recovery skills. 5,40 None of these lines of research, however, are related to the resection of relevant cortical regions or disconnection of cortical tracts in animals undergoing acute and chronic models of generalized, multifocal, or limbic epileptic induction and cortical reorganization.…”