Spinally targeted paired associated stimulation with high-frequency peripheral component induces spinal level plasticity in healthy subjects.

A novel variant of paired-associative stimulation (PAS) consisting of high-frequency peripheral nerve stimulation (PNS) and high-intensity transcranial magnetic stimulation (TMS) above the motor cortex, called high-PAS, can lead to improved motor function in patients with incomplete spinal cord injury. In PAS, the interstimulus interval (ISI) between the PNS and TMS pulses plays a significant role in the location of the intended effect of the induced plastic changes. While conventional PAS protocols (single TMS pulse often applied with intensity close to resting motor threshold, and single PNS pulse) usually require precisely defined ISIs, high-PAS can induce plasticity at a wide range of ISIs and also in spite of small ISI errors, which is helpful in clinical settings where precise ISI determination can be challenging.

Effects of auricular vagus nerve stimulation and electrical earlobe stimulation on motor-evoked potential changes induced by paired associative stimulation.

Paired associative stimulation (PAS) is a combination of transcranial magnetic stimulation (TMS) and peripheral nerve stimulation (PNS). PAS can induce long-term potentiation (LTP)-like plasticity in humans, manifested as motor-evoked potential (MEP) enhancement. We have developed a variant of PAS ("high-PAS"), which consists of high-frequency PNS and high-intensity TMS and targets spinal plasticity and promotes rehabilitation after spinal cord injury (SCI).

Study Design for Navigated Repetitive Transcranial Magnetic Stimulation for Speech Cortical Mapping.

The cortical areas involved in human speech should be characterized reliably prior to surgery for brain tumors or drug-resistant epilepsy. The functional mapping of language areas for surgical decision-making is usually done invasively by electrical direct cortical stimulation (DCS), which is used to identify the organization of the crucial cortical and subcortical structures within each patient. Accurate preoperative non-invasive mapping aids surgical planning, reduces time, costs, and risks in the operating room, and provides an alternative for patients not suitable for awake craniotomy.

Optimal peripheral nerve stimulation intensity for paired associative stimulation with high-frequency peripheral component in healthy subjects.

Paired associative stimulation (PAS) with high-frequency peripheral nerve stimulation (PNS), called "high-PAS", induces motor-evoked potential (MEP) potentiation in healthy subjects and improves muscle activity and independence in incomplete spinal cord injury patients. Data on optimal PNS intensity in PAS are scarce. In a high-PAS protocol, PNS intensity is defined as "minimal intensity required to produce F-responses".

A Randomized, Sham-Controlled Trial of Repetitive Transcranial Magnetic Stimulation Targeting M1 and S2 in Central Poststroke Pain: A Pilot Trial.

Objectives: Central poststroke pain (CPSP), a neuropathic pain condition, is difficult to treat. Repetitive transcranial magnetic stimulation (rTMS) targeted to the primary motor cortex (M1) can alleviate the condition, but not all patients respond. We aimed to assess a promising alternative rTMS target, the secondary somatosensory cortex (S2), for CPSP treatment.

Effect of long-term paired associative stimulation on the modulation of cortical sensorimotor oscillations after spinal cord injury.

Study Design: A prospective interventional case series.

Objectives: To explore changes in the modulation of cortical sensorimotor oscillations after long-term paired associative stimulation (PAS) in participants with spinal cord injury (SCI).

Setting: BioMag Laboratory, HUS Diagnostic Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.

A novel paired associative stimulation protocol with a high-frequency peripheral component: A review on results in spinal cord injury rehabilitation.

In recent decades, a multitude of therapeutic approaches has been developed for spinal cord injury (SCI), but few have progressed to regular clinical practice. Novel non-invasive, cost-effective, and feasible approaches to treat this challenging condition are needed. A novel variant of paired associative stimulation (PAS), high-PAS, consists of non-invasive high-intensity transcranial magnetic stimulation (TMS) and non-invasive high-frequency electrical peripheral nerve stimulation (PNS).

Effects of Long-Term Paired Associative Stimulation on Strength of Leg Muscles and Walking in Chronic Tetraplegia: A Proof-of-Concept Pilot Study.

Recovery of lower-limb function after spinal cord injury (SCI) is dependent on the extent of remaining neural transmission in the corticospinal pathway. The aim of this proof-of-concept pilot study was to explore the effects of long-term paired associative stimulation (PAS) on leg muscle strength and walking in people with SCI. Five individuals with traumatic incomplete chronic tetraplegia (>34 months post-injury, motor incomplete, 3 females, mean age 60 years) with no contraindications to transcranial magnetic stimulation (TMS) received PAS to one or both legs for 2 months (28 sessions in total, 5 times a week for the first 2 weeks and 3 times a week thereafter).

Interictal magnetoencephalography in parietal lobe epilepsy - Comparison of equivalent current dipole and beamformer (SAMepi) analysis.

Objective: To evaluate a novel analysis method (SAMepi) in the localization of interictal epileptiform magnetoencephalographic (MEG) activity in parietal lobe epilepsy (PLE) patients in comparison with equivalent current dipole (ECD) analysis.

Methods: We analyzed the preoperative interictal MEG of 17 operated PLE patients utilizing visual analysis and: (1) ECD with a spherical conductor model; (2) ECD with a boundary element method (BEM) conductor model; and (3) SAMepi - a kurtosis beamformer method. Localization results were compared between the three methods, to the location of the resection and to the clinical outcome.

Paired associative stimulation improves hand function after non-traumatic spinal cord injury: A case series.

Objectives: Long-term paired associative stimulation (PAS) is a non-invasive combination of transcranial magnetic stimulation and peripheral nerve stimulation and leads to improved hand motor function in individuals with incomplete traumatic tetraplegia. Spinal cord injuries (SCIs) can also be induced by neurological diseases. We tested a similar long-term PAS approach in patients with non-traumatic neurological SCI.

The use of electronic coil location control for focal magnetic stimulation at the cervical level.

Background: Accurate re-positioning of the coil is challenging in magnetic stimulation at the cervical spinal level. The applicability of coil location control for this type of stimulation is unexplored.

New Method: Utilizing a figure-of-eight coil and anatomy-specific models of the magnetic stimulation system, we developed a novel technique that enables probing corticospinal excitability at the cervical spinal level.

A simple magnetoencephalographic auditory paradigm may aid in confirming left-hemispheric language dominance in epilepsy patients.

Objective: The intracarotid amobarbital procedure (IAP) is the current "gold standard" in the preoperative assessment of language lateralization in epilepsy surgery candidates. It is, however, invasive and has several limitations. Here we tested a simple noninvasive language lateralization test performed with magnetoencephalography (MEG).

Long-Term Paired Associative Stimulation Enhances Motor Output of the Tetraplegic Hand.

A large proportion of spinal cord injuries (SCI) are incomplete. Even in clinically complete injuries, silent non-functional connections can be present. Therapeutic approaches that can strengthen transmission in weak neural connections to improve motor performance are needed.

Long-term paired associative stimulation can restore voluntary control over paralyzed muscles in incomplete chronic spinal cord injury patients.

Emerging therapeutic strategies for spinal cord injury aim at sparing or restoring at least part of the corticospinal tract at the acute stage. Hence, approaches that strengthen the weak connections that are spared or restored are crucial. Transient plastic changes in the human corticospinal tract can be induced through paired associative stimulation, a noninvasive technique in which transcranial magnetic brain stimulation is synchronized with electrical peripheral nerve stimulation.

The use of F-response in defining interstimulus intervals appropriate for LTP-like plasticity induction in lower limb spinal paired associative stimulation.

Background: In spinal paired associative stimulation (PAS), orthodromic volleys are induced by transcranial magnetic stimulation (TMS) in upper motor neurons, and antidromic volleys by peripheral nerve stimulation (PNS) in lower motor neurons of human corticospinal tract. The volleys arriving synchronously to the corticomotoneuronal synapses induce spike time-dependent plasticity in the spinal cord. For clinical use of spinal PAS, it is important to develop protocols that reliably induce facilitation of corticospinal transmission.

Alterations in spontaneous brain oscillations during stroke recovery.

Amplitude or frequency alterations of spontaneous brain oscillations may reveal pathological phenomena in the brain or predict recovery from brain lesions, but the temporal evolution and the functional significance of these changes is not well known. We performed follow-up recordings of spontaneous brain oscillations with whole-head MEG in 16 patients with first-ever stroke in the middle cerebral artery territory, affecting upper limb motor function, 1-7 days (T0), 1 month (T1), and 3 months (T2) after stroke, with concomitant clinical examination. Clinical test results improved significantly from T0 to T1 or T2.

Effect of afferent input on motor cortex excitability during stroke recovery.

Objective: Afferent input is proposed to mediate its effect on motor functions by modulating the excitability of the motor cortex. We aimed to clarify - in a longitudinal study - how afferent input affects motor cortex excitability after stroke and how it is associated with recovery of hand function.

Methods: The motor cortex excitability was studied by measuring the reactivity of the motor cortex beta rhythm to somatosensory stimulation.

Pre- and post-operative diffusion tensor imaging of the median nerve in carpal tunnel syndrome.

Objectives: To use pre- and post-operative diffusion tensor imaging (DTI) to monitor median nerve integrity in patients suffering from carpal tunnel syndrome (CTS).

Methods: Diffusivity and anisotropy images along the median nerve were compared among 12 patients, 12 age-matched and 12 young control subjects and correlated with electrophysiological neurography results. Slice-wise DTI parameter values were calculated to focus on local changes.

Activation in parietal operculum parallels motor recovery in stroke.

Motor recovery after stroke requires continuous interaction of motor and somatosensory systems. Integration of somatosensory feedback with motor programs is needed for the automatic adjustment of the speed, range, and strength of the movement. We recorded somatosensory evoked fields (SEFs) to tactile finger stimulation with whole-scalp magnetoencephalography in 23 acute stroke patients at 1 week, 1 month, and 3 months after stroke to investigate how deficits in the somatosensory cortical network affect motor recovery.

Reorganization of the primary somatosensory cortex during stroke recovery.

Objective: Animal and human studies have indicated that stroke induces reorganization of the motor and somatosensory cortices. We aimed to clarify how changes in the primary somatosensory (SI) cortex correlate with stroke recovery.

Methods: We recorded somatosensory evoked fields (SEFs) with magnetoencephalography from 15 patients with stroke affecting upper extremity motor function.

Motor cortex dysfunction in complex regional pain syndrome.

Objective: Most patients with complex regional pain syndrome (CRPS) exhibit debilitating motor symptoms. The effect of continuous pain on motor system in CRPS, however, is not well known. We searched for signs of motor cortex dysfunction in chronic CRPS type 1 patients with motor impairment.

Cortical reorganization in primary somatosensory cortex in patients with unilateral chronic pain.

Unlabelled: Bodily representations of the primary somatosensory (SI) cortex are constantly modified according to sensory input. Increased input due to training as well as loss of input due to deafferentation are reflected as changes in the extent of cortical representations. Recent studies in complex regional pain syndrome (CRPS) patients have indicated that the chronic pain itself is associated with cortical reorganization.

Changes in brain function and morphology in patients with recurring herpes simplex virus infections and chronic pain.

A recent study described for the first time a patient group that suffered from spontaneous chronic pain and from recurrent herpes simplex virus (HSV) infections. The patients had pain in widespread areas on one side of the body and were--due to subtle immunological abnormalities--susceptible to HSV infections. Although the clinical features of the pain suggested involvement of the central nervous system, supporting evidence for this was lacking.

Magnetoencephalography in neurosurgery.

Objective: To present applications of magnetoencephalography (MEG) in studies of neurosurgical patients.

Methods: MEG maps magnetic fields generated by electric currents in the brain, and allows the localization of brain areas producing evoked sensory responses and spontaneous electromagnetic activity. The identified sources can be integrated with other imaging modalities, e.