Changes in cerebral cortex activity during a simple motor task after MRgFUS treatment in patients affected by essential tremor and Parkinson's disease: a pilot study using functional NIRS.

Objective.Magnetic resonance imaging-guided focused ultrasound surgery (MRgFUS) is a non-invasive thermal ablation method that involves high-intensity focused ultrasound surgery (FUS) and Magnetic Resonance Imaging for anatomical imaging and real-time thermal mapping. This technique is widely employed for the treatment of patients affected by essential tremor (ET) and Parkinson's disease (PD). In the current study, functional near-infrared spectroscopy (fNIRS) was used to highlight hemodynamics changes in cerebral cortex activity, during a simple hand motor task, i.e. unimanual left and right finger-tapping, in ET and PD patients.Approach.All patients were evaluated before, one week and one month after MRgFUS treatment.Main results.fNIRS revealed cerebral hemodynamic changes one week and one month after MRgFUS treatment, especially in the ET group, that showed a significant clinical improvement in tremor clinical scores.Significance.To our knowledge, our study is the first that showed the use of fNIRS system to measure the cortical activity changes following unilateral ventral intermediate nucleus thalamotomy after MRgFUS treatment. Our findings showed that therapeutic MRgFUS promoted the remodeling of neuronal networks and changes in cortical activity in association with symptomatic improvements.

Normal pressure hydrocephalus: Neurophysiological and neuropsychological aspects: a narrative review.

ABSTRACT: Idiopathic normal pressure hydrocephalus (NPH) is a syndrome that affects elderly people and is characterized by excessive accumulation of cerebrospinal fluid in the brain ventricles. Diagnosis is based on the evaluation of clinical symptoms, which consists of a classic triad (Hakim triad), gait disturbances, cognitive impairment, and urinary incontinence. However, this complete triad is not always seen; therefore, it is difficult to make the diagnosis. NPH can be divided into primary or idiopathic NPH and secondary NPH. Diagnostic criteria for NPH remain a topic of discussion; however, the development of diagnostic techniques has brought new opportunities for diagnosis. The aim of this review is to present an overview of neurophysiological and neuropsychological approaches to support the clinical evaluation of patients with NPH and contribute to the differential diagnosis of NPH and dementia, as the clinical symptoms of NPH may resemble other neurodegenerative disorders.

Cognitive impairment in obstructive sleep apnea syndrome: a descriptive review.

PURPOSE: Obstructive sleep apnea syndrome is a clinical sleep disorder defined by total or partial airflow restraint during sleep that results in fragmented sleep and hypoxemia, impacting negatively with cognitive functioning. This review was conducted on studies investigating structural brain alteration and cognitive impairment in obstructive sleep apnea syndrome. METHOD: We searched on PubMed databases and screening references of included studies and review articles for additional citations. From initial 190 publications, only 17 met search criteria and described the cognitive impairment in obstructive sleep apnea syndrome. RESULTS: Findings showed that patients with this syndrome had worse performance than healthy controls in attention, memory, and executive functions, showing specific neuroanathomical features. Cognitive impairment is also related to the severity of pathology. Treatment could improve certain cognitive aspects. CONCLUSIONS: Cognitive deficits seem to be mainly attributable to decreased daytime vigilance and nocturnal hypoxemia.

Assessment of spinal cord stimulation and radiofrequency: Chronic pain and psychological impact.

Pain has a major impact on anxiety and depression levels. The aim of this study is to demonstrate how these symptoms (depression and anxiety) could positively influence the perception of pain after neurostimulation system implantation.We enrolled 100 patients and divided in 2 different groups, by using tests screening such as Beck Depression Inventory (BDI), Hamilton Anxiety Rating Scale (HAM-A), Nursing Rating Scale (NRS): the group with spinal cord stimulation (SCS) and the group with pulsed spinal cord radiofrequency (RFP).We highlighted a significant decrease of scores (BDI, HAM-A, NRS) in each group between T0 (baseline) and T1. Moreover, the intra-group analysis showed a positive significant correlation between NRS and depressive and anxiety symptoms.We assert that the use of alternative methods (SCS and RFP) to the traditional pharmaceutical-surgical treatments, provide the reduction of the algic and anxiety-depressant symptoms, restoring also the perception of psychological well-being.

Quantitative assessment of Parkinsonian tremor by using biosensor device.

Parkinson disease (PD) is the second most common neurodegenerative disease which affects population older than 65 years. Tremor represents one of the main symptomatic triads in PD, particularly in rest state.We enrolled 41 idiopathic PD patients, to validate the assessment of tremor symptoms.To be enrolled in the study, patients had to fulfill the movement disorder society clinical diagnostic criteria for PD.We used an innovative home-made, low-cost device, able to quantify the frequency and amplitude of rest tremor and stress conditionOur results confirmed the presence of tremor during muscular effort in a significant number of patients and the influence of emotional stress.We suppose that this new device should be validated in clinical practice as a support of differential diagnosis and therapeutic management of PD patients.

fMRI and electroencephalographic evaluation of sleep deprivation in epilepsy patients: An observational study.

BACKGROUND: Sleep deprivation (SD) is considered an important activation test to facilitate the visualization of electroencephalogram (EEG) epileptic abnormalities, in order to perform a correct diagnosis. OBJECTIVE: The aim of this study was to evaluate the local functional activity in healthy controls (HC) subjects and left mesial temporal lobe epilepsy-hippocampal sclerosis patients, after a SD, by using functional Magnetic Resonance Imaging (fMRI) and EEG. MATERIALS AND METHODS: We enrolled 22 healthy controls and 34 patients with a diagnosis of left mesial temporal lobe epilepsy-hippocampal sclerosis. Each participant underwent two examinations separately: an fMRI study using 3 T MRI to detect spontaneous activity during the RS-fMRI and an EEG. RESULTS: The SD-EEG results showed the presence of epileptiform discharges predominantly in left fronto-centro-temporal areas. fMRI findings if compared to HC showed an increase of functional activity in some areas. DISCUSSION: We showed that SD-EEG study confirmed a high specificity to assess a specific diagnosis. Therefore, the decrease of activity observed in DMN could be explain by a different amount of sleep/awake time during fMRI recording in the two groups or the interictal activity during fMRI acquisition. Our study highlighted alterated functional activity in SD cortical areas of epileptic patients if compared to HC.

Treatment of pain post-brachial plexus injury using high-frequency spinal cord stimulation.

PURPOSE: Brachial plexopathy can sometimes cause severe chronic pain. There are many possible treatments for such neuropathic pain, including neuromodulation. However, rigorous scientific evidence on the usefulness of spinal cord stimulation (SCS) is still scarce. Here, we report the use of high-frequency (10 kHz) SCS (HFSCS) in a patient with brachial plexus injury (root avulsion). OBJECTIVE: To assess the efficacy of HFSCS in root avulsion and to investigate the putative neurophysiological mechanisms of HFSCS. METHODS: A 32-year-old woman visited our center following an iatrogenic brachial plexus injury. She underwent traditional, paresthesia-inducing, tonic SCS with cervical lead placement. She reported that stimulation-induced paresthesia was uncomfortable, without any pain reduction. After the successful trial of HFSCS, the patient was assessed at 1 month (T1) and 6 months (T6) after HFSCS implantation with pain and quality of life (QoL) scales. Moreover, she underwent a neurophysiological assessment (somatosensory evoked potentials [SEPs], reciprocal inhibition [RI], pain-motor integration [PMI], and the habituation of intraepidermal electrical stimulation-induced evoked potentials [IEPs]) with the stimulator switched on and switched off at T6. RESULTS: The patient reported 100% paresthesia-free pain relief, a consistent improvement of QoL, and a complete discontinuation of her previous pain treatment at T1 and T6. Moreover, we found suppression of SEPs, restored habituation of IEPs, and strengthening of RI and PMI. CONCLUSION: This is the first report to illustrate the usefulness and safety of HFSCS for treating root avulsion in a patient with failed tonic SCS. Our data indicate that HFSCS may either block large-diameter fibers or stimulate medium-/small-diameter fibers, thus inducing analgesia without paresthesia, probably by reducing the activation of the wide-dynamic-range neurons. Moreover, HFSCS seems to modulate spinal inhibitory mechanisms and the descending corticospinal inhibitory output. Thus, HFSCS can be an effective option for treating refractory pain following root avulsion.

Functional MRI and laser-evoked potentials evaluation in Charcot-Marie-Tooth syndrome.

Charcot-Marie-Tooth (CMT) disease is a genetically heterogeneous group of disorders. Pain is a less common symptom complained by CMT patients. We described a case of a 39-year-old male patient affect by Charcot-Marie-Tooth (CMT) disease compared to five healthy controls (HC), to assess the sensory and the nociceptive pathways by using LEPs recording associated to fMRI examination, to find an "objective" marker which could be used in the management of CMT patient. The nociceptive system was evaluated by laser-evoked potentials (LEPs). Moreover, fMRI (functional magnetic resonance imaging) examination, by using laser stimuli, was performed. LEPs' examination showed an increase of latency and an amplitude reduction respect to HC. The laser stimulation during fMRI showed a decreased cortical activations if compared to HC. The originality of this paper, although limited to a single case, resides in a detailed evaluation of CMT1 patient performed by using neurophysiologic and neuroimaging methods to investigate extensively the sensory nociceptive pathways.

Promising Role of Neuromodulation in Predicting the Progression of Mild Cognitive Impairment to Dementia.

The differential diagnosis of mild cognitive impairment (MCI) and Alzheimer's disease (AD) is not always straightforward, and the rate of progression of MCI to dementia is not negligible. Thus, there is a need for para-clinical approaches that can improve the differential diagnosis and identify patients that are at risk of progression. There is a growing interest, at present, in the role of the deterioration of brain oscillations as a predictor of MCI-to-AD conversion. For this reason, we experimentally modulated γ-band oscillations (GBO) in a sample of MCI and AD patients and an age-matched healthy elderly group, using a transcranial alternating current stimulation (tACS) protocol that was applied to different cortical sites. We correlated the after-effects of tACS on the GBO and the neuropsychological data, in an attempt to differentiate MCI from AD patients and identify, among the MCI patients, those that could be at potential risk of MCI-to-dementia conversion. MCI patients showed a partial GBO increase and improvement in some neuropsychological tests whereas AD individuals did not show significant tACS after-effects. Notably, some MCI subjects lacked significant neuropsychological and electrophysiological after-effects, similar to AD individuals. In a two-year follow-up, such MCI individuals had converted into AD. Therefore, our data suggest that tACS may support the clinical differential diagnosis of MCI and AD and identify MCI patients who could be at risk of developing dementia. This prediction index may help the clinician to adopt a better prevention/follow-up strategy in such a disabling neurodegenerative disease.

Could combined sleep and pain evaluation be useful in the diagnosis of disorders of consciousness (DOC)? Preliminary findings.

BACKGROUND: The diagnosis of Disorders of Consciousness (DOC) is still challenging. Indeed, ~ 40% of patients in vegetative state (VS) are misdiagnosed, suggesting the need of more appropriate diagnostic tools. Emerging data are showing that EEG, including sleep structure evaluation and multimodal evoked potential recording could be helpful in DOC diagnosis. Moreover, pain perception evaluation could further increase diagnosis accuracy in such individuals. METHODS: Fourteen individuals with DOC, due to severe brain injury, were enrolled and admitted to the Intensive Neurorehabilitation Unit of the Research Institute. All patients were evaluated by means of the Coma Recovery Scale-Revised, a 24(hh)-polysomnography and a Laser Evoked Potential (LEP) paradigm. RESULTS: Clinically-defined patients in Minimally Consciousness State showed a more preserved sleep structure, physiologic hypnic figures and preserved REM/NREM sleep distribution than subjects in VS. LEP showed increased latencies and reduced amplitudes and were also detectable in patients with more structured sleep. CONCLUSIONS: The data support previous findings concerning the importance of sleep study in DOC diagnosis, with more specific neurophysiological paradigms. Interestingly, the findings shed some light on the possible correlations among global brain connectivity, sleep structure and pain perception, which are related to the activity of the wide thalamo-cortical and cortico-cortical networks underlying consciousness.

Neurofunctional assessment in a case of calculation-induced seizures.

Previous studies suggest a localized activation of specific areas in healthy subjects during mental calculation. We report the case of patient affected by calculation-induced seizures that were refractory to medications. We showed the cortical activation by using a functional magnetic resonance imaging (fMRI) while he was performing an arithmetic task and illustrated that, in this case, the areas commonly activated included the premotor and supplementary motor areas of both hemispheres. Furthermore, the patient showed a more significant activation of posterior parietal and prefrontal cortices after arithmetic tasks if compared to normal controls. To our knowledge, this is the first fMRI study in calculation-induced seizures, even if limited to a single patient. The potential benefits of non-conventional neuroimaging technology, such as fMRI, for understanding calculation, however, are only beginning to be tapped.

Migraine with and without aura: electrophysiological and functional neuroimaging evidence.

The neuropathological processes believed to underlie migraine with and without aura are still widely debated in the literature. In order to arrive at a more detailed and comprehensive picture of the altered processes present in migraineurs, electrophysiological data obtained through transcranial magnetic stimulation (TMS) and electroencephalography (EEG) were combined with haemodynamic data obtained through functional magnetic resonance imaging (fMRI). Ten subjects affected by migraine (with or without aura) underwent TMS and EEG investigation prior to a visual stimulation task, studied in fMRI. Our preliminary results showed a reduced cortical silent period especially in subjects affected by migraine with aura. The fMRI BOLD response was found to be weaker in occipital areas proportionally to the frequency and severity of migraine attacks. The data obtained from our study seem to support the theory of cortical spreading depression recently observed in human subjects. Moreover, the electrophysiological data were also correlated to migraine attack frequency, thus pointing to elevated cortical excitability between attacks. Better understanding of the neuropathological processes that trigger migraine attacks will help in the selection of more adequate prophylactic therapies. The results of this preliminary study need to be confirmed in a a large sample of subjects.

Cortical silent period prolongation in spinocerebellar ataxia type 2 (SCA2).

Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant neurodegenerative disorder mapped on chromosome 12. Different results have been reported in spinocerebellar ataxias following transcranial magnetic stimulation (TMS). TMS-induced cortical silent period (CSP) was prolonged in different cerebellar disorders. Here we evaluate the duration of the TMS-induced CSP following a single magnetic stimulus in a large homogeneous group of SCA2 patients compared with idiopathic cerebellar ataxia (IDCA) patients with similar disease duration and severity, and in 20 healthy controls. The CSP duration in both arm and leg muscles was significantly (p<0.005) longer in patients than in controls. A significant positive correlation between disease duration and CSP prolongation in both SCA2 and IDCA was found. No correlation between age, onset and CSP duration emerged in either group. This study shows a prolongation of the TMS-induced silent period in both SCA2 and IDCA indicating that the cortical inhibitory mechanism is dependent on the disease duration and severity. Thus, the cerebellum seems to exert a pliable physiological influence on the cortico-spinal system through control of inhibitory cortical interneurons.