Fine-grained nociceptive maps in primary somatosensory cortex

Topographic maps of the receptive surface are a fundamental feature of neural organization in many sensory systems. While touch is finely mapped in the cerebral cortex, it remains controversial how precise any cortical nociceptive map may be. Given that nociceptive innervation density is relatively low on distal skin regions such as the digits, one might conclude that the nociceptive system lacks fine representation of these regions. Indeed, only gross spatial organization of nociceptive maps has been reported so far. However, here we reveal the existence of fine-grained somatotopy for nociceptive inputs to the digits in human primary somatosensory cortex (SI). Using painful nociceptive-selective laser stimuli to the hand, and phase-encoded fMRI analysis methods, we observed somatotopic maps of the digits in contralateral SI. These nociceptive maps were highly aligned with maps of non-painful tactile stimuli, suggesting comparable cortical representations for, and possible interactions between, mechanoreceptive and nociceptive signals. Our findings may also be valuable for future studies tracking the timecourse and the spatial pattern of plastic changes in cortical organization involved in chronic pain

Linking pain and the body: neural correlates of visually induced analgesia

The visual context of seeing the body can reduce the experience of acute pain, producing a multisensory analgesia. Here we investigated the neural correlates of this “visually induced analgesia” using fMRI. We induced acute pain with an infrared laser while human participants looked either at their stimulated right hand or at another object. Behavioral results confirmed the expected analgesic effect of seeing the body, while fMRI results revealed an associated reduction of laser-induced activity in ipsilateral primary somatosensory cortex (SI) and contralateral operculoinsular cortex during the visual context of seeing the body. We further identified two known cortical networks activated by sensory stimulation: (1) a set of brain areas consistently activated by painful stimuli (the so-called “pain matrix”), and (2) an extensive set of posterior brain areas activated by the visual perception of the body (“visual body network”). Connectivity analyses via psychophysiological interactions revealed that the visual context of seeing the body increased effective connectivity (i.e., functional coupling) between posterior parietal nodes of the visual body network and the purported pain matrix. Increased connectivity with these posterior parietal nodes was seen for several pain-related regions, including somatosensory area SII, anterior and posterior insula, and anterior cingulate cortex. These findings suggest that visually induced analgesia does not involve an overall reduction of the cortical response elicited by laser stimulation, but is consequent to the interplay between the brain's pain network and a posterior network for body perception, resulting in modulation of the experience of pain

Transcranial magnetic stimulation over human secondary somatosensory cortex disrupts perception of pain intensity.

Pain is a complex sensory experience resulting from the activity of a network of brain regions. However, the functional contribution of individual regions in this network remains poorly understood. We delivered single-pulse transcranial magnetic stimulation (TMS) to the contralateral primary somatosensory cortex (S1), secondary somatosensory cortex (S2) and vertex (control site) 120 msec after selective stimulation of nociceptive afferents using neodymium:yttrium-aluminium-perovskite (Nd:YAP) laser pulses causing painful sensations. Participants were required to judge either the intensity (medium/high) or the spatial location (proximal/distal) of the stimulus in a two-alternative forced choice paradigm. When TMS pulses were delivered over S2, participants' ability to judge pain intensity was disrupted, as compared to S1 and vertex (control) stimulation. Signal-detection analysis demonstrated a loss of sensitivity to stimulation intensity, rather than a shift in perceived pain level or response bias. We did not find any effect of TMS on the ability to localise nociceptive stimuli on the skin. The novel finding that TMS over S2 can disrupt perception of pain intensity suggests a causal role for S2 in encoding of pain intensity

Paroxysmal tonic upgaze. physiopathological considerations in three additional cases

In questo articolo vengono discussi tre casi clinici sottolineando gli elementi per la differenziazione elettro-clinica di movimenti parossistici oculari con alcune epilessie idiopatiche e lesionali della età evolutiva.Paroxysmal tonic upgaze of childhood has been described as a benign distinctive syndrome of abnormal ocular movement, with or:without concomitant ataxia. After the first observation of four children, a further 29 patients have been reported with a wide spectrum of neurologic abnormalities such as ataxia, unsteady of gait, learning disabilities and mental retardation at follow-up. Electroencephalograms were normal in all the subjects and magnetic resonance imaging showed deficient myelination in only one patient. Recently it has been suggested that paroxysmal tonic upgaze could be a heterogeneous syndrome, ranging from a simply age-dependent manifestation to a clinical appearance of a variety of disorders affecting the corticomesencephalic loop of vertical eye movement, Moreover, it also could be an early sign of more widespread neurologic dysfunction. We describe three patients who presented paroxysmal tonic upgaze; in one, ataxia was present; in the second child, ata;da and language disorder also-were observed; and in the third patient paroxysmal tonic upgaze was associated with loss of muscle tone (drop-attack-like events). On magnetic resonance imaging, a pinealoma compressing the dorsal mesencephalic region was detected. On the basis of our observations, we suggest that any insult with periaqueductal mesencephalic gray-matter involvement could be considered the basic condition for this peculiar clinical manifestation

Comparing Spray Characteristics from Reynolds Averaged Navier-Stokes (RANS) National Combustion Code (NCC) Calculations Against Experimental Data for a Turbulent Reacting Flow

Developing physics-based tools to aid in reducing harmful combustion emissions, like Nitrogen Oxides (NOx), Carbon Monoxide (CO), Unburnt Hydrocarbons (UHC s), and Sulfur Dioxides (SOx), is an important goal of aeronautics research at NASA. As part of that effort, NASA Glenn Research Center is performing a detailed assessment and validation of an in-house combustion CFD code known as the National Combustion Code (NCC) for turbulent reacting flows. To assess the current capabilities of NCC for simulating turbulent reacting flows with liquid jet fuel injection, a set of Single Swirler Lean Direct Injection (LDI) experiments performed at the University of Cincinnati was chosen as an initial validation data set. This Jet-A/air combustion experiment operates at a lean equivalence ratio of 0.75 at atmospheric pressure and has a 4 percent static pressure drop across the swirler. Detailed comparisons of NCC predictions for gas temperature and gaseous emissions (CO and NOx) against this experiment are considered in a previous work. The current paper is focused on detailed comparisons of the spray characteristics (radial profiles of drop size distribution and at several radial rakes) from NCC simulations against the experimental data. Comparisons against experimental data show that the use of the correlation for primary spray break-up implemented by Raju in the NCC produces most realistic results, but this result needs to be improved. Given the single or ten step chemical kinetics models, use of a spray size correlation gives similar, acceptable result

Should "migralepsy" be considered an obsolete concept? A multicenter retrospective clinical/EEG study and review of the literature.

The few reports that have been published on the current International Classification of Headache Disorders, Second Edition (ICHD-II), criteria for migralepsy and hemicrania epileptica have highlighted the considerable confusion regarding this "hot topic" within both headache and epilepsy classifications (ICHD-II and International League Against Epilepsy [ILAE]). Indeed, the ICHD-II describes a migraine-triggered seizure as a rare event in which a seizure occurs during migraine aura; on the other hand, hemicrania epileptica is described as an "ictal headache" that occurs "synchronously" with a partial seizure. To confuse matters even further, neither the term migralepsy nor the term hemicrania epileptica is included in the currently used ILAE classification. On the basis of both a review of "migralepsy" cases in the literature and 16 additional retrospective multicenter cases, we suggest that the term migraine-triggered seizure or migralepsy be deleted from the ICHD-II classification until unequivocal evidence is provided of its existence, and that the term ictal epileptic headache be introduced into the ILAE classification

Saliency Detection as a Reactive Process: Unexpected Sensory Events Evoke Corticomuscular Coupling.

Survival in a fast-changing environment requires animals not only to detect unexpected sensory events, but also to react. In humans, these salient sensory events generate large electrocortical responses, which have been traditionally interpreted within the sensory domain. Here we describe a basic physiological mechanism coupling saliency-related cortical responses with motor output. In four experiments conducted on 70 healthy participants, we show that salient substartle sensory stimuli modulate isometric force exertion by human participants, and that this modulation is tightly coupled with electrocortical activity elicited by the same stimuli. We obtained four main results. First, the force modulation follows a complex triphasic pattern consisting of alternating decreases and increases of force, time-locked to stimulus onset. Second, this modulation occurs regardless of the sensory modality of the eliciting stimulus. Third, the magnitude of the force modulation is predicted by the amplitude of the electrocortical activity elicited by the same stimuli. Fourth, both neural and motor effects are not reflexive but depend on contextual factors. Together, these results indicate that sudden environmental stimuli have an immediate effect on motor processing, through a tight corticomuscular coupling. These observations suggest that saliency detection is not merely perceptive but reactive, preparing the animal for subsequent appropriate actions.SIGNIFICANCE STATEMENT Salient events occurring in the environment, regardless of their modalities, elicit large electrical brain responses, dominated by a widespread "vertex" negative-positive potential. This response is the largest synchronization of neural activity that can be recorded from a healthy human being. Current interpretations assume that this vertex potential reflects sensory processes. Contrary to this general assumption, we show that the vertex potential is strongly coupled with a modulation of muscular activity that follows the same pattern. Both the vertex potential and its motor effects are not reflexive but strongly depend on contextual factors. These results reconceptualize the significance of these evoked electrocortical responses, suggesting that saliency detection is not merely perceptive but reactive, preparing the animal for subsequent appropriate actions

Peri-ictal and inter-ictal headache in children and adolescents with idiopathic epilepsy: a multicenter cross-sectional study.

PURPOSE: Headache in epileptic population ranges from 8% to 15%. The aim of this paper was to study the clinical and temporal characteristics of primary headache comorbidity in idiopathic epileptic children. METHODS: From June 2006 to June 2009, a cross-sectional multi-center study involving five Italian Child Neurology University Centers (two in Rome, one in Chieti, one in Naples, and one in L'Aquila) was conducted. Among 1,264 consecutively newly diagnosed, idiopathic, partial, or generalized, epileptic children, according to ILAE diagnostic criteria (aged between 5 and 15 years of age), we selected 142 children (11.2%) (130 of whom completed the study) who showed an associated peri-ictal and/or inter-ictal headache diagnosed according to the International Headache Society Criteria. Rare cases of "ictal epileptic headache", in which headache represents the sole ictal epileptic manifestation, were excluded from this study. RESULTS AND CONCLUSIONS: Post-ictal headaches were most frequent (62%). Pre-ictal headaches were less common (30%). Inter-ictal headaches were described in 57.6%. Clear migrainous features were present in 93% of pre-ictal and 81.4% of post-ictal headaches. Inter-ictal headaches meet criteria for migraines in 87%. The association between partial epilepsy and migraine without aura is most common and reported in 82% of our patients with peri-ictal headache and in 76.5% of patients with post-ictal headache

Long term outcome in children affected by absence epilepsy with onset before the age of three years.

OBJECTIVE: The goal of this study was to define the long-term outcome of absence epilepsy presenting before the age of 3 years. METHODS: We retrospectively studied the medical records of 40 children from eight neuropediatric centers in Italy with respect to the personal and family histories of epilepsy or febrile seizures, time of follow-up, cognitive functions, treatment, and outcome. RESULTS: Forty patients were enrolled in this study. They all fulfilled the criteria for absence epilepsy with 3-Hz spike-wave complexes on the EEG, normal neurological examination, and no other seizures types. Seizure onset occurred between 24.1 and 36.0 months. There was a family history of epilepsy in 28%, and of febrile seizures in 13%. Thirty-three patients were treated with valproic acid (VPA), mostly used in monotherapy (26 patients) or in association with ethosuximide. At final follow-up, 33 patients were seizure free and 29 had normal EEGs. Thirty-four patients had a normal intelligence quotient (IQ), whereas 6 had a decreased IQ, mainly associated with poor control of seizures. CONCLUSION: In our series, absence seizures presenting before the age of 3 appeared to have quite a good long-term clinical prognosis; the neuropsychological outcome was comparable to that of childhood epilepsy presenting after 3 years of age

Pseudoaneurisma di origine traumatica localizzato in un seno sfenoidale fratturato

Descriviamo il caso di un pseudoaneurisma di origine traumatica dell’arteria carotide interna destra localizzato all’interno di un seno sfenoidale fratturato che si è sviluppato in un paziente che aveva riportato delle fratture dell’osso frontale e della base cranica che coinvolgevano le pareti del seno sfenoidale e il canale della carotide malgrado l’angio-TC precoce fosse negativa. Il paziente ha presentato due episodi di epistassi ritardata massiva potenzialmente letale prima di essere trattato con successo con tecniche endovascolari utilizzanti spirali metalliche e uno stent non ricoperto. Questo caso sottolinea il fatto che i pazienti con trauma cranico che presentano fratture nel seno sfenoidale con o senza epistassi massiva dovrebbero essere studiati il più presto possibile alla ricerca dello sviluppo di uno pseudoaneurisma postraumatico della carotide interna. Se la prima angio-TC è negativa, un’epistassi ricorrente dovrebbe condurre alla realizzazione di una seconda angio-TC poiché lo pseudoaneurisma richiede tempo per svilupparsi. Un trattamento endovascolare precoce con uno stent non ricoperto può impedire il decesso del paziente