Navigation-guided core needle biopsy for skull base and parapharyngeal lesions: a five-year experience

The aim of this study was to evaluate the diagnostic accuracy of navigation-guided core needle biopsy for skull base and parapharyngeal lesions. Twenty patients with skull base and parapharyngeal lesions were included in this study. The preoperative design and intraoperative real-time image guiding was done using an optical navigation system. A spring-loaded semi-automatic biopsy gun and biopsy needle were used for specimen harvesting. Accuracy was established on the basis of the postoperative pathology. All patients underwent needle biopsy successfully without any immediate or delayed complications. The subzygomatic approach was adopted in all cases. The number of passes ranged from three to five. The diagnostic accuracy was 90% (18/20). Navigation-guided core needle biopsy offers an easy approach for the diagnosis of skull base and parapharyngeal lesions, with a high yield of specimens and good patient tolerance.     

Abnormal motor surround inhibition associated with cortical and deep grey matter involvement in multiple sclerosis

ObjectiveMotor surround inhibition (mSI) is a physiological mechanism that contributes to hand movement control by focusing voluntary movement. Growing evidence suggests that hand movement control is impaired in multiple sclerosis. The aim of the study was to evaluate mSI in MS and to investigate the brain structures involved in mSI in multiple sclerosis.MethodsWe recruited 33 patients and 23 controls. To investigate mSI, we delivered transcranial magnetic single pulses during index finger flexion. Motor evoked potentials were recorded and first dorsal interosseous (“active muscle”) and from the abductor digiti minimi (“surround muscle”). mSI was expressed as the ratio between Motor evoked potentials recorded from the surround muscle during movement and at rest. Participants underwent a magnetic resonance study.ResultsPatients had impaired mSI as compared with controls. Magnetic resonance showed that basal ganglia had smaller volumes and higher mean diffusivity than controls. Impaired mSI correlated with primary motor cortex and basal ganglia involvement in multiple sclerosis.ConclusionAltered mSI in multiple sclerosis is related to cortical and subcortical grey matter involvement.SignificanceOur study provides the first demonstration of a pathophysiological mechanism underlying hand movement control dysfunction in multiple sclerosis. mSI represents a new therapeutic target of multiple sclerosis rehabilitative approaches.     

Pathological generosity: An atypical impulse control disorder after a left subcortical stroke

Changes in socio-emotional behavior and conduct, which are characteristic symptoms of frontal lobe damage, have less often been described in patients with focal subcortical injuries. We report on a case of pathological generosity secondary to a left lenticulocapsular stroke with hypoperfusion of several anatomically intact cortical areas. A 49-year-old man developed excessive and persistent generosity as he recovered from a left lenticulocapsular hematoma. His symptoms resembled an impulse control disorder. ^99mTc-HMPAO SPECT demonstrated hypoperfusion mostly in the ipsilateral striatum, dorsolateral, and orbitofrontal cortex. This case study adds pathological generosity to the range of behavioral changes that may result from discrete unilateral lesions of the lenticular nucleus and nearby pathways. In our particular case, post-stroke pathological generosity was not ascribable to disinhibition, apathy, mania, or depression. Because pathological generosity may lead to significant distress and financial burden upon patients and their families, it may warrant further consideration as a potential type of impulse control disorder.     

Adjustments in the force–frequency relationship during passive and exercise‐induced hyperthermia

Introduction: We examined the extent to which fatiguing cycling exercise in the heat influences contractile function in modulating the force–frequency relationship. Methods: Before (∽37.0°C) and after (∽38.5°C) exercise (ExH) and passive (PaH) hyperthermia, an 8‐s train of stimulation at 10, 20, 50, and 100 Hz (2 s per frequency) and a potentiated twitch were evoked on the relaxed knee extensors using percutaneous stimulation. Results: ExH and PaH produced a decrease in the 20:50 Hz force ratio, indicative of low‐frequency fatigue (P < 0.01). This adjustment was more pronounced after ExH than PaH (P < 0.01). A rightward displacement in the force–frequency relationship occurred after ExH and PaH (P < 0.05) and was exacerbated by ExH (P < 0.05). Peak twitch force also decreased after ExH (P < 0.05). Conclusions: ExH reduces force summation due to development of skeletal muscle fatigue, exacerbating the shift in force–frequency to the right relative to PaH. Muscle Nerve 50 : 822–829, 2014     

Longitudinal study of diffusion tensor imaging properties of affected cortical spinal tracts in acute and chronic hemorrhagic stroke

This study investigated the clinical value of diffusion tensor imaging (DTI) in predicting the motor outcome in patients with basal ganglia hemorrhage. This prospective study included 23 patients assessed with DTI to measure the fractional anisotropy (FA) value in affected cortical spinal tract (CST) at three time points: day 0, day 30 and day 90 after onset. The motor function score (MFS) was applied to evaluate motor function and patients were divided into good and poor outcome groups according to the MFS on day 90. The mean FA value on day 0 was significantly lower in the poor outcome group than in the good outcome group (p < 0.01). FA value gradually decreased in the poor outcome group until day 90 after onset, while it continuously increased in the good outcome group. The MFS obtained at day 90 after onset was significantly correlated with the initial FA value in the affected cerebral peduncle (r = −0.926, p < 0.01). Receiver operating characteristic curve analysis showed that the FA value on day 0 could predict motor function outcome with a sensitivity of 88.89% and specificity of 92.86% at the initial FA value of 0.45. The FA value of affected CST in acute cerebral hemorrhage may valuably predict the motor function outcome and its dynamic change may represent the Wallerian degeneration in motor tracts after hemorrhagic stroke.     

Serotonin transporter gene polymorphisms and treatment-resistant depression

Major Depression Disorder (MDD) is a serious mental illness that is one of the most disabling diseases worldwide. In addition, approximately 15% of depression patients are defined treatment-resistant (TRD). Preclinical and genetic studies show that serotonin modulation dysfunction exists in patients with TRD. Some polymorphisms in the promoter region of the serotonin transporter gene (SLC6A4) are likely to be involved in the pathogenesis/treatment of MDD; however, no data are available concerning TRD.     

Pathological considerations in the treatment of Parkinson's disease: More than just a wiring diagram

Parkinson's disease (PD) represents a common but challenging condition in which an increasing number of therapeutic options have evolved over the course of the last 50 years. The introduction of dopaminergic therapies has dramatically improved outcomes but life expectancies remain significantly curtailed. Currently, all available treatment options are directed towards the amelioration of symptoms. However, it is hoped that a greater understanding of the distinctive pathology underlying PD might offer some novel therapeutic approaches.The identification of degeneration within the nigrostriatal tract as the most prominent pathological process in PD has led to the development of a number of therapies. However, despite initially good symptomatic control it has become clear that the longer-term use of these medications is associated with a number of debilitating motor complications. The management of these drug-related issues has necessitated a further tier of therapeutic options based largely on a greater understanding of the basal ganglia circuitry involved. Indeed, surgical interventions targeting these neural circuits have provided increased control of motor symptoms in patients with advanced disease, however, such techniques still fail to slow or reverse the disease. To this end, a number of novel approaches focussed on restoration or repair of the diseased brain have received increasing attention. Nevertheless, there are multiple symptoms that are unresponsive to any of these therapies, highlighting the involvement of other neurotransmitter systems and the complexities of the disease beyond the basal ganglia circuitry. An appreciation of the ongoing neurodegenerative processes at the core of PD and the burden of disease associated with them, emphasises the need for increased research into more effective and comprehensive treatment methodologies.     

The neurocircuitry involved in oxytocin modulation of methamphetamine addiction

The role of oxytocin in attenuating the abuse of licit and illicit drugs, including the psychostimulant methamphetamine, has been examined with increased ferocity in recent years. This is largely driven by the potential application of oxytocin as a pharmacotherapy. However, the neural mechanisms by which oxytocin modulates methamphetamine abuse are not well understood. Recent research identified an important role for the accumbens core and subthalamic nucleus in this process, which likely involves an interaction with dopamine, glutamate, GABA, and vasopressin. In addition to providing an overview of methamphetamine, the endogenous oxytocin system, and the effects of exogenous oxytocin on drug abuse, we propose a neural circuit through which exogenous oxytocin modulates methamphetamine abuse, focusing on its interaction with neurochemicals within the accumbens core and subthalamic nucleus. A growing understanding of exogenous oxytocin effects at a neurochemical and neurobiological level will assist in its evaluation as a pharmacotherapy for drug addiction.