Francesco Brigo

Functional brain reorganization after spinal cord injury: Systematic review of animal and human studies

Plastic changes of neural circuits occur after spinal cord injury (SCI) at various level of the central nervous system. In this review we will focus on delineating the pathophysiological mechanisms of the brain plasticity changes following SCI, based on the existing neuroimaging and neurophysiological evidence in experimental models and humans. In animal experiments, reorganization of the sensory topography as well as of the topographical map of primary motor and premotor cortices have been reported in several studies. Brain imaging revealed that cortical representation in response to spared forelimb stimulation early enlarges and invades adjacent sensory-deprived hind limb territory. Electrophysiological studies demonstrated that the deafferentation due to SCI can immediately change the state of large cortical networks within 1h, and that these changes play a critical role in the functional reorganization after SCI. In humans neuroimaging also showed shifts of functional motor and sensory cortical representations that relate to the severity of SCI. In patients with cervical SCI, cortical forearm motor representations, as assessed by means of transcranial magnetic stimulation, may reorganize towards the intrinsic hand motor representation to maximize output to muscles of the impaired forearm. Excessive or aberrant reorganisation of cerebral cortex may also have pathological consequences, such as phantom sensations or neuropathic pain. Integrated neuroimaging and neurophysiological approaches may also lead to the development of new therapeutic strategies, which have the potential of enhancing sensorimotor recovery in patients with SCI.

Intermittent rhythmic delta activity patterns.

Intermittent rhythmic delta activity is a typical EEG pattern that was originally described by W.A. Cobb in 1945 (J Neurol Neurosurg Psychiatr 1945;8:65-78). It may be classified into three distinct forms according to the main cortical region involved on the EEG: frontal (FIRDA), temporal (TIRDA), and occipital (OIRDA) intermittent delta activity. This article is a review of the main aspects of these patterns, with a special focus on EEG features and problems that may be encountered during interpretation of these patterns. In contrast to FIRDA and OIRDA, TIRDA is highly indicative of ipsilateral pathology. OIRDA and TIRDA are highly correlated with epilepsy, whereas FIRDA is a rather nonspecific EEG pattern.

Nonintravenous midazolam versus intravenous or rectal diazepam for the treatment of early status epilepticus: A systematic review with meta-analysis

BACKGROUND Prompt treatment of status epilepticus (SE) is associated with better outcomes. Rectal diazepam (DZP) and nonintravenous (non-IV) midazolam (MDZ) are often used in the treatment of early SE instead of intravenous applications. The aim of this review was to determine if nonintravenous MDZ is as effective and safe as intravenous or rectal DZP in terminating early SE seizures in children and adults. METHODS We searched the Cochrane Central Register of Controlled Trials (CENTRAL), ClinicalTrials.gov, and MEDLINE for randomized controlled trials comparing non-IV MDZ with DZP (by any route) in patients (all ages) with early SE defined either as seizures lasting >5 min or as seizures at arrival in the emergency department. The following outcomes were assessed: clinical seizure cessation within 15 min of drug administration, serious adverse effects, time interval to drug administration, and time from arrival in the emergency department to seizure cessation. Outcomes were assessed using a random-effects Mantel-Haenszel meta-analysis to calculate risk ratio (RR), odds ratio (OR) and mean difference with 95% confidence intervals (95% CIs). RESULTS Nineteen studies with 1933 seizures in 1602 patients (some trials included patients with more than one seizure) were included. One thousand five hundred seventy-three patients were younger than 16 years. For seizure cessation, non-IV MDZ was as effective as DZP (any route) (1933 seizures; RR: 1.03; 95% CIs: 0.98 to 1.08). No difference in adverse effects was found between non-IM MDZ and DZP by any route (1933 seizures; RR: 0.87; 95% CIs: 0.50 to 1.50). Time interval between arrival and seizure cessation was significantly shorter with non-IV MDZ by any route than with DZP by any route (338 seizures; mean difference: -3.67 min; 95% CIs: -5.98 to -1.36); a similar result was found for time from arrival to drug administration (348 seizures; mean difference: -3.56 min; 95% CIs: -5.00 to -2.11). A minimal difference was found for time interval from drug administration to clinical seizure cessation, which was shorter for DZP by any route than for non-IV MDZ by any route (812 seizures; mean difference: 0.56 min; 95% CIs: 0.15 to 0.98 min). Not all studies reported information on time intervals. Comparison by each way of administration failed to find a significant difference in terms of clinical seizure cessation and occurrence of adverse effects. The only exception was the comparison between buccal MDZ and rectal DZP, where MDZ was more effective than rectal DZP in terminating SE but only when results were expressed as OR (769 seizures; OR: 1.78; 95% CIs: 1.11 to 2.85; RR: 1.15; 95% CIs: 0.85 to 1.54). Only one study was entirely conducted in an adult population (21 patients, aged 31 to 69 years), showing no difference in efficacy or time to seizure cessation after drug administration between intranasal MDZ and rectal DZP. CONCLUSIONS Non-IV MDZ is as effective and safe as intravenous or rectal DZP in terminating early SE in children and probably also in adults. Times from arrival in the emergency department to drug administration and to seizure cessation are shorter with non-IV MDZ than with intravenous or rectal DZP, but this does not necessarily result in higher seizure control. An exception may be the buccal MDZ, which, besides being socially more acceptable and easier to administer, might also have a higher efficacy than rectal DZP in seizure control. This article is part of a Special Issue entitled Status Epilepticus.

Functional evaluation of central cholinergic circuits in patients with Parkinson's disease and REM sleep behavior disorder: a TMS study.

Central cholinergic dysfunction has been reported in patients with Parkinsonʼs disease (PD) and hallucinations by evaluating short latency afferent inhibition (SAI), a transcranial magnetic stimulation protocol which gives the possibility to test an inhibitory cholinergic circuit in the human brain. REM sleep behavior disorder (RBD) was also found to be associated with cognitive impairment in PD patients. The objective of the study was to assess the cholinergic function, as measured by SAI, in PD patients with RBD (PD-RBD) and PD patients without RBD (PD-nRBD). We applied the SAI technique in 10 PD-RBD patients, in 13 PD-nRBD patients and in 15 age-matched normal controls. All PD patients and control subjects also underwent a comprehensive battery of neuropsychological tests. Mean SAI was significantly reduced in PD-RBD patients when compared with PD-nRBD patients and controls. Neuropsychological examination showed mild cognitive impairment in 9 out of the 10 PD-RBD patients, and in 5 out of the 13 PD-nRBD. SAI values correlated positively with neuropsychological tests measuring episodic verbal memory, executive functions, visuoconstructional and visuoperceptual abilities. Similar to that previously reported in the idiopathic form of RBD, SAI abnormalities suggest a cholinergic dysfunction in PD patients who develop cognitive impairment, and present findings indicate that RBD is an important determinant of MCI in PD.

Thiamine Deficiency Induced Neurochemical, Neuroanatomical, and Neuropsychological Alterations: A Reappraisal

Nutritional deficiency can cause, mainly in chronic alcoholic subjects, the Wernicke encephalopathy and its chronic neurological sequela, the Wernicke-Korsakoff syndrome (WKS). Long-term chronic ethanol abuse results in hippocampal and cortical cell loss. Thiamine deficiency also alters principally hippocampal- and frontal cortical-dependent neurochemistry; moreover in WKS patients, important pathological damage to the diencephalon can occur. In fact, the amnesic syndrome typical for WKS is mainly due to the damage in the diencephalic-hippocampal circuitry, including thalamic nuclei and mammillary bodies. The loss of cholinergic cells in the basal forebrain region results in decreased cholinergic input to the hippocampus and the cortex and reduced choline acetyltransferase and acetylcholinesterase activities and function, as well as in acetylcholine receptor downregulation within these brain regions. In this narrative review, we will focus on the neurochemical, neuroanatomical, and neuropsychological studies shedding light on the effects of thiamine deficiency in experimental models and in humans.

Invasive and non-invasive brain stimulation for treatment of neuropathic pain in patients with spinal cord injury: A review

Abstract Context Past evidence has shown that invasive and non-invasive brain stimulation may be effective for relieving central pain. Objective To perform a topical review of the literature on brain neurostimulation techniques in patients with chronic neuropathic pain due to traumatic spinal cord injury (SCI) and to assess the current evidence for their therapeutic efficacy. Methods A MEDLINE search was performed using following terms: “Spinal cord injury”, “Neuropathic pain”, “Brain stimulation”, “Deep brain stimulation” (DBS), “Motor cortex stimulation” (MCS), “Transcranial magnetic stimulation” (TMS), “Transcranial direct current stimulation” (tDCS), “Cranial electrotherapy stimulation” (CES). Results Invasive neurostimulation therapies, in particular DBS and epidural MCS, have shown promise as treatments for neuropathic and phantom limb pain. However, the long-term efficacy of DBS is low, while MCS has a relatively higher potential with lesser complications that DBS. Among the non-invasive techniques, there is accumulating evidence that repetitive TMS can produce analgesic effects in healthy subjects undergoing laboratory-induced pain and in chronic pain conditions of various etiologies, at least partially and transiently. Another very safe technique of non-invasive brain stimulation – tDCS – applied over the sensory-motor cortex has been reported to decrease pain sensation and increase pain threshold in healthy subjects. CES has also proved to be effective in managing some types of pain, including neuropathic pain in subjects with SCI. Conclusion A number of studies have begun to use non-invasive neuromodulatory techniques therapeutically to relieve neuropathic pain and phantom phenomena in patients with SCI. However, further studies are warranted to corroborate the early findings and confirm different targets and stimulation paradigms. The utility of these protocols in combination with pharmacological approaches should also be explored.

[¹²³I]FP-CIT SPECT (DaTSCAN) may be a useful tool to differentiate between Parkinson's disease and vascular or drug-induced parkinsonisms: a meta-analysis.

Differentiating idiopathic Parkinsons disease from secondary parkinsonian syndromes is crucial since their management and prognosis differ considerably. Functional imaging of the dopaminergic pathway by means of [¹²³I]FP‐CIT SPECT (DaTSCAN) might be useful in this regard, but its role is still controversial. The accuracy of DaTSCAN in the differential diagnosis between Parkinsons disease and vascular or drug‐induced parkinsonism was therefore systematically reviewed.

Transcranial magnetic stimulation (TMS)/repetitive TMS in mild cognitive impairment and Alzheimer's disease

Several Transcranial Magnetic Stimulation (TMS) techniques can be applied to noninvasively measure cortical excitability and brain plasticity in humans. TMS has been used to assess neuroplastic changes in Alzheimers disease (AD), corroborating findings that cortical physiology is altered in AD due to the underlying neurodegenerative process. In fact, many TMS studies have provided physiological evidence of abnormalities in cortical excitability, connectivity, and plasticity in patients with AD. Moreover, the combination of TMS with other neurophysiological techniques, such as high‐density electroencephalography (EEG), makes it possible to study local and network cortical plasticity directly. Interestingly, several TMS studies revealed abnormalities in patients with early AD and even with mild cognitive impairment (MCI), thus enabling early identification of subjects in whom the cholinergic degeneration has occurred. Furthermore, TMS can influence brain function if delivered repetitively; repetitive TMS (rTMS) is capable of modulating cortical excitability and inducing long‐lasting neuroplastic changes. Preliminary findings have suggested that rTMS can enhance performances on several cognitive functions impaired in AD and MCI. However, further well‐controlled studies with appropriate methodology in larger patient cohorts are needed to replicate and extend the initial findings. The purpose of this paper was to provide an updated and comprehensive systematic review of the studies that have employed TMS/rTMS in patients with MCI and AD.

Pharmacologic treatment of status epilepticus

ABSTRACT Introduction: Status epilepticus (SE) requires rapid identification of its cause and urgent pharmacological treatment. Despite an estimated incidence of up to 61 per 100,000 per year, evidence from high-class clinical trials is only available for the early stages of SE. Areas covered: Following a four-stage approach of SE (early, established, refractory and super-refractory), we present pharmacological treatment options and their clinical utility. Expert opinion: Intravenous lorazepam and intramuscular midazolam appear as most effective treatments for early SE. In children, buccal midazolam has emerged as first-line non-intravenous drug with similar efficacy and safety to other intravenous or rectal benzodiazepines. In established SE intravenous antiepileptic drugs are in use. There are no double-blind, but six randomized open studies with valproate and two with levetiracetam. A meta-analysis found higher rates of seizure cessation with valproate 75.7% (95% CI 63.7–84.8) and phenobarbital 73.6%, (95% CI 58.3–84.8) than with levetiracetam (68.5%, 95% CI 56.2–78.7) or phenytoin (50.2%, 95% CI 34.2–66.1). Based on the favourable tolerability profile of levetiracetam and valproate, the authors prefer these drugs in established SE over phenytoin. Treatment options in refractory SE are intravenous anaesthetics. In super-refractory SE ketamine, magnesium, steroids and other drugs have been used with variable outcomes. At this stage therapeutic decisions are based on doctors’ preferences, patient factors such as age and comorbidity, and cause of SE, if identified.

Recent advances in status epilepticus.

PURPOSE OF REVIEW This review discusses advances in the understanding of the mechanisms of status epilepticus and its current treatment approaches. Many of these have been topics at the 5th London-Innsbruck Colloquium on status epilepticus 2015. RECENT FINDINGS A new definition and classification of status epilepticus was proposed, which is expected to improve treatment and stimulate research. A better understanding of the failure of seizure suppressing mechanisms and the initiation of self-sustaining seizures begins to translate into the clinical arena. Drugs, such as allopregnanolone, cannabinoids, sec-butylpropylacetamide and valnoctamide, may better target these seizure-perpetuating mechanisms. The concept of combinatorial treatments has further developed, but yet trials in humans are lacking. A new prognostic outcome-score and electroencephalography-criteria for nonconvulsive status epilepticus are ready for clinical use. Alternative routes, such as intranasal or buccal, have been explored in a number of trials suggesting that intramuscular midazolam is at least as effective as intravenous lorazepam and buccal or intranasal midazolam is at least as effective as rectal diazepam. SUMMARY Despite progress in basic science, translation into the clinical field remains difficult. There is hope, that the two large phase III studies in the established and refractory status that started recruitment in 2015 will better inform the clinicians in this emergency situation.