Effects of deep brain stimulation frequency on eye movements and cognitive control

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an effective treatment for Parkinson's disease (PD). Varying the frequency DBS has differential effects on axial and distal limb functions, suggesting differing modulation of relevant pathways. The STN is also a critical node in oculomotor and associative networks, but the effect of stimulation frequency on these networks remains unknown. This study aimed to investigate the effects of 80 hz vs. 130 Hz frequency STN-DBS on eye movements and executive control. Twenty-one STN-DBS PD patients receiving 130 Hz vs. 80 Hz stimulation were compared to a healthy control group (n = 16). All participants were tested twice in a double-blind manner. We examined prosaccades (latency and gain) and antisaccades (latency of correct and incorrect antisaccades, error rate and gain of the correct antisaccades). Executive function was tested with the Stroop task. The motor condition was assessed using Unified Parkinson's Disease Rating Scale part III. The antisaccadic error rate was higher in patients (p = 0.0113), more so in patients on 80 Hz compared to 130 Hz (p = 0.001) stimulation. The differences between patients and controls and between frequencies for all other eye-movements or cognitive measures were not statistically significant. We show that 80 Hz STN-DBS in PD reduces the ability to maintain stable fixation but does not alter inhibition, resulting in a higher antisaccade error rate presumably due to less efficient fixation, without altering the motor state. This provides a wider range of stimulation parameters that can reduce specific DBS-related effects without affecting motor outcomes

Étude de nouveaux outils de programmation pour la stimulation cérébrale profonde du noyau sous-thalamique dans la maladie de Parkinson

La stimulation cérébrale profonde des noyaux sous-thalamiques est un traitement chirurgical de la maladie de Parkinson avancée. La programmation clinique post-opératoire des paramètres de stimulation est une étape critique pour obtenir l'effet thérapeutique escompté. Pourtant, dans certains cas, la stimulation cérébrale profonde reste grevée d'effets secondaires ou d'un effet thérapeutique insuffisant. Cela est en partie dû à la connaissance incomplète des effets du courant électrique sur l'activité des réseaux neuronaux pathologiques de la maladie de Parkinson. Le développement de nouvelles électrodes et paramètres de stimulation par l'industrie apporte l'espoir de meilleurs résultats cliniques. Ces nouveaux outils rendent aussi la programmation clinique plus complexe. Nous présentons deux études explorant comment deux nouveaux outils technologiques, la largeur d'impulsion d'une part, et les sources indépendantes de courant continu d'autre part, permettent d'améliorer l'efficacité et la tolérance de la stimulation des noyaux sous-thalamiques, tout en s'intégrant dans une approche systématique de programmation clinique

Recurrent Bilateral Papilledema Initially Mimicking Idiopathic Intracranial Hypertension In Granulomatosis with Polyangiitis

Granulomatosis with polyangiitis (GPA) may involve the central nervous system and manifest as pachymeningitis. Usual clinical findings include headaches and various cranial neuropathies. Although inconsistently reported, papilledema and intracranial hypertension may be a complication of GPA with pachymeningitis, as a result of the obstruction of venous outflow by thickened meninges. We describe a case of GPA that initially manifested with recurrent papilledema and intracranial hypertension, mimicking idiopathic intracranial hypertension

Forgotten Fundus Findings in Wernicke's Encephalopathy

Wernicke's encephalopathy (WE) is an acute-onset neurological emergency caused by thiamine deficiency, and can occur after bariatric surgery. It is characterized by the classic triad of acute altered mental status, ophthalmoplegia and/or nystagmus, and gait ataxia. Fundus findings in WE are less well characterized. We report a WE patient with peripapillary changes that resolved after treatment

Is the Treatment Working? Yes, the Patient Is Getting Worse!

A 46-year-old woman from Gambia with no prior medical history presented to the ophthalmology clinic for progressive blurred vision, headache, and weight loss over the past two months. Her best corrected visual acuity was finger count in the right eye and 20/20 in the left eye

Première crise d'épilepsie : prise en charge pratique

First seizures are a diagnostic challenge in the emergency room. The differential diagnosis includes epileptic seizures, syncopes and psychogenic non-epileptic seizures. Importantly, amongst first epileptic seizures, acute symptomatic seizures should be distinguished from unprovoked seizures that define epilepsy. The early accurate diagnosis of first seizures is an important issue because of the therapeutic and prognostic implications at stake. In addition to gathering a detailed history, some ancillary tests may be warranted early on in patients' management. In this article, we present some definitions and describe clinical and work up features that might help accurately classify and appropriately manage such cases in the emergency room.Les crises épileptiques inaugurales arrivant aux urgences représentent un enjeu diagnostique de taille. Le diagnostic différentiel d'une première crise épileptique comprend notamment les syncopes convulsivantes et les crises psychogènes non épileptiques. En cas de première crise épileptique, savoir identifier une crise provoquée d'une crise d'épilepsie-maladie est un autre défi. L'enjeu diagnostique initial est donc important car les implications thérapeutiques et pronostiques sont différentes selon l'étiologie retenue. Outre l'anamnèse très détaillée, un certain nombre d'examens spécialisés doivent être réalisés de manière précoce. Nous présentons dans cet article des éléments diagnostiques cliniques et paracliniques à mettre en œuvre dans la prise en charge précoce des patients

Diagnosis of optic disc oedema : fundus features, ocular imaging findings, and artificial intelligence

Optic disc swelling is a manifestation of a broad range of processes affecting the optic nerve head and/or the anterior segment of the optic nerve. Accurately diagnosing optic disc oedema, grading its severity, and recognising its cause, is crucial in order to treat patients in a timely manner and limit vision loss. Some ocular fundus features, in light of a patient's history and visual symptoms, may suggest a specific mechanism or aetiology of the visible disc oedema, but current criteria can at most enable an educated guess as to the most likely cause. In many cases only the clinical evolution and ancillary testing can inform the exact diagnosis. The development of ocular fundus imaging, including colour fundus photography, fluorescein angiography, optical coherence tomography, and multimodal imaging, has provided assistance in quantifying swelling, distinguishing true optic disc oedema from pseudo-optic disc oedema, and differentiating among the numerous causes of acute optic disc oedema. However, the diagnosis of disc oedema is often delayed or not made in busy emergency departments and outpatient neurology clinics. Indeed, most non-eye care providers are not able to accurately perform ocular fundus examination, increasing the risk of diagnostic errors in acute neurological settings. The implementation of non-mydriatic fundus photography and artificial intelligence technology in the diagnostic process addresses these important gaps in clinical practice.</p

Focused Ultrasound Ablation in Parkinson’s Disease

Comment on : Krishna V, Fishman PS, Eisenberg HM, Kaplitt M, Baltuch G, Chang JW, Chang WC, Martinez Fernandez R, Del Alamo M, Halpern CH, Ghanouni P, Eleopra R, Cosgrove R, Guridi J, Gwinn R, Khemani P, Lozano AM, McDannold N, Fasano A, Constantinescu M, Schlesinger I, Dalvi A, Elias WJ. Trial of Globus Pallidus Focused Ultrasound Ablation in Parkinson's Disease. N Engl J Med. 2023 Feb 23;388(8):683-693. doi: 10.1056/NEJMoa2202721. PMID: 36812432. </p