Notch Phenomenon Research Articles

Fenómeno de Kernohan-Woltman: ¿un cuadro neurológico excepcional?

IntroductionIpsilateral hemiparesis (IH) can be defined as a paradoxical dysfunction of the first motor neuron involving the extremities on the opposite side to that expected, given the location of the triggering intracranial pathology. Compression of the corticospinal tract (CSt) along its course through the contralateral cerebral peduncle against the free edge of the tentorium, known as the Kernohan-Woltman notch phenomenon (KWNP), represents the main cause of IH. MethodsThis retrospective study analyzes a series of 12 patients diagnosed with IH secondary to KWNP treated at our institution, including a descriptive study of epidemiological, clinical, radiological, neurophysiological, and prognostic variables. ResultsIn 75% of the cases, symptoms had an acute or subacute onset. Initial imaging studies showed signs of significant mass effect in half of the patients, whereas magnetic resonance imaging (MRI) identified a structural lesion in the contralateral cerebral peduncle in two thirds of them. Impairment of the motor evoked potentials (MEP) was verified in 4 patients. During follow-up 7 patients experienced improvement in motor activity, and near half of the cases were classified in the first three categories of the modified Rankin scale. ConclusionsIn contrast to prior historical series, most of our patients developed a KWNP secondary to a traumatic mechanism. MRI represents the optimal method to identify both the classic cerebral peduncle notch and the underlying structural lesion of the CSt. The use of MEP can help to establish the diagnosis, especially in those cases lacking definite radiological findings.

In Reply to the Letter to the Editor Regarding “Kernohan-Woltman Notch Phenomenon Following Acute Subdural Hematoma”

In Reply to the Letter to the Editor Regarding “Kernohan-Woltman Notch Phenomenon Following Acute Subdural Hematoma”

Letter to the Editor Regarding “Kernohan–Woltman Notch Phenomenon Following Acute Subdural Hematoma”

Letter to the Editor Regarding “Kernohan–Woltman Notch Phenomenon Following Acute Subdural Hematoma”

Kernohan-Woltman notch phenomenon in traumatic brain injury patient: A case series

Kernohan-Woltman notch phenomenon in traumatic brain injury patient: A case series

Kernohan-Woltman Notch Phenomenon Following Acute Subdural Hematoma

A 72-year-old right-handed female patient was operated on for left-sided acute subdural hematoma responsible for coma. Two weeks afterward, her neurological status had improved with a Glasgow Coma Scale score of 14 and a paradoxical left-sided hemiparesis. The brain magnetic resonance imaging displayed a diffusion-restricting, hyper fluid-attenuated inversion recovery lesion of the right cerebral peduncle facing the tentorial notch, and the patient was diagnosed with Kernohan-Woltman notch phenomenon. This allowed to focus the neurological rehabiliation on the ipsilateral motor deficit as well as the hemineglect.

Syndrome of the third frontal convolution: Léon Ectors´ legacy on paradoxical ipsilateral hemiparesis.

Since the crossed control of sensitive-motor body functions by the contralateral cerebral hemispheres was recognized in the early 18th century, clinicians have been baffled by patients developing a motor deficit involving the extremities on the same side as an intracranial lesion. In the first third of the 20th century, three main hypotheses were proposed to explain this so-called ipsilateral or paradoxical hemiparesis: (1) the absence of decussation of the corticospinal tracts; (2) diaschisis, or blocking of the normal input to a brain region anatomically distant from the injured site; and (3) compression of the contralateral cerebral peduncle against the tentorial border, also known as the Kernohan-Woltman notch phenomenon. Here, we deal with the less widely known contributions of the Belgian neurosurgeon Léon Ectors, who included this paradoxical deficit within a neurological syndrome he considered highly specific for an early diagnosis of those meningiomas growing over the third frontal convolution. The present manuscript includes a systematic review of the cases of ipsilateral hemiparesis secondary to intracranial masses reported in ancient and modern scientific medical literature. We also address in-depth the physiopathological theories accounting for this syndrome and contrast them with Léon Ectors' observations.

Paradoxical Hemiparesis from Cerebellopontine Angle Tumor: A Case Report

Objective: To report a vestibular schwannoma in the cerebellopontine angle presenting with paradoxical hemiparesis with the Kernohan-Woltman Notch Phenomenon (KWNP).Methods: A 31-year-old female presented to the neurology clinic at Bhayangkara Hospital TK. I R. Said Sukanto, Indonesia, on 29 November 2021 with loss of balance, hearing, vision, and weakness in her left arm and leg. On physical examination, the patient had reduced left arm and leg muscle strengths against resistance (MRC grade 4), face deviation to the left, abnormal finger-to-nose test, dysdiadochokinesia, and inability to perform tandem gait. She was admitted for a brain MRI but did not return to the hospital for re-evaluation and surgery. Results: The brain MRI showed a mass on the left side of the cerebellum with a size of 4.44x3.93x4.93 cm, suggesting vestibular schwannoma. The mass also caused the obliteration of the ventricle, causing hydrocephalus.Conclusion:KWNP is an unusual finding resulting in a paradoxical hemiparesis, a false-localizing neurologic sign. Physicians should recognize KWNP in patients with hemiparesis, especially in space-occupying lesions. Imaging studies can help localize the lesion to minimize misdiagnosis and optimize patient treatment.

The Kinetics of Transtentorial Brain Herniation: Kernohan-Woltman Notch Phenomenon Revisited.

To critically review recent literature in understanding the pathological consequences of transtentorial brain herniation resulting from unilateral expanding supratentorial mass lesions. Modern neuroimaging assists in understanding the consequences of transtentorial brain herniation with the development of the Kernohan-Woltman notch phenomenon. MRI studies in post-operative patients undergoing craniotomy and removal of expanding unilateral hemispheric mass lesions (usually an extradural or subdural hematoma) have shown striking findings in the contralateral crus cerebri suggestive of damage as a result of impact against the free margin of the opposite tentorium as suggested by Kernohan and Woltman nearly a century back in autopsy studies. MR changes include T1 hypointensity, T2 and fluid-attenuated inversion recovery (FLAIR) hyperintensity, DW1 hyperintensity with restriction of diffusion, presence of hypointensity in GRE sequences and evidence of axonal damage in the corticospinal tracts in the cerebral peduncle in diffusion tensor imaging and MR tractography. The pathological basis of such changes may be variable or a combination of several pathological processes, which may all be related to the impact/compression of the contralateral crus with the tentorial margin. These include contusion, compression, demyelination, and perhaps most importantly microvascular damage including microbleeds. The role of uncal herniation is debatable. It appears that as a result of massive lateral shift in the supratentorial compartment, there is a transient forceful impact of the opposite cerebral peduncle against the rigid tentorial border to induce one or more of the abovementioned phenomena to explain the imaging findings. The limitation of these studies is that most of them have been done in the post-operative periods and surgical manipulations can surely alter anatomical relationships between intracranial structures. The exact sequence of events happening intracranially in the face of rapidly expanding supratentorial mass lesions is largely unknown. Even with rapid progress in neuroimaging, documentation of such changes during life are difficult, principally for logistic reasons. Consequently, the very truth of the much taught about phenomenon of uncal herniation and the resultant Kernohan-Woltman notch phenomenon and the false localizing sign of unilateral motor weakness and contralateral pupillary dilation have been questioned. Animal experimentation and autopsy studies have not contributed much in our understanding of the actual process happening intracranially in such an emergent situation. The midbrain undoubtedly is the key structure bearing the brunt of the effect of brain shift which is more lateral than downward in cases with unilateral expanding lesions. Structural changes in the cerebral peduncles have now been visualized with modern neuroimaging. These alterations may result from the interplay of one or more factors which include compression, contusion, demyelination, and perhaps most importantly microvascular ischemia and hemorrhage resulting from a forceful yet transient impact of the cerebral peduncle with the tough tentorial margin. The last mentioned hypothesis would be in conformity with Kernohan and Woltman's concept of elastic deformation of the midbrain. In the present article an attempt is made to provide a historical account of the changing concepts in relation to brain herniation as systematically and chronologically as possible, and then, critically review recent neuroimaging observations with a view to hypothesize on the sequence of events during transtentorial brain herniation.

Kernohan–Woltman notch phenomenon in patient with subdural hematoma and ipsilateral hemiparesis in Bukavu

Key Clinical MessageKernohan–Woltman phenomenon is a rare and paradoxical neurological situation in which a transtentorial lesion leads to compression of the contralateral cerebral peduncle responsible for compression of the descending corticospinal fibers with clinical consequence of a motor deficit ipsilateral to the primary lesion. This phenomenon should attract the attention of clinicians in order to avoid unfortunate incidents such as wrong‐side craniotomy in neurosurgical practice. In this work, we report a similar situation.AbstractThe Kernohan–Woltman notch phenomenon is a rare and paradoxical neurological situation in which transtentorial damage is observed leading to compression of the contralateral cerebral peduncle responsible for compression of descending corticospinal fibers with the clinical consequence of a motor deficit ipsilateral to the primary lesion. This phenomenon has been found in several situations including tumors and cerebral hematomas after craniocerebral trauma. In this work, we have reported the case of a 52‐year‐old man with hemiparesis ipsilateral to a large chronic subdural hematoma.

Novel aortic heart valve model parameterizing normal and pathological cases: Aortic stenosis and regurgitation

In this paper, a novel heart valve model with parameters selections enabling to illustrate some physiological patterns such as healthy, aortic stenosis, and regurgitation has been shown. The motion of the elastic leaflet body is modeled by a nonlinear mass–spring–damper and coupled with a cardiovascular lumped parameter model. As a result, our model takes in to account a single continuous time-varying fluid resistance, the aortic flow rate, left ventricular and aortic pressures, and the leaflets’ pose. This novel model is able to show the backflow, vortex and dicrotic notch phenomenon as approaching to the gold standard in physiological evaluation. The model also additionally presents reverse pressure effect on the aortic valve in the diastolic phase that is not observed in the recent literature. The physiological validation is performed by comparing two reference models and previously reported on physiological data. Nominal leaflet spring ( α) and damping (c) parameters have been determined for the healthy valve ( α = 0.1, c = 2), aortic stenosis ( α = 0.005, c = 0.1), and aortic regurgitation ( α = 0.001, c = 2). When compared to other studies, the left ventricular and aortic pressure, leaflets’ opening-closing angles are generated in similar patterns. In addition, the reduction of the blood flow rate can now be observed in aortic regurgitation, which is not presented in the literature. In conclusion, a set of critical aortic valve conditions is parameterized by our novel model. The elastic structure of the leaflet model enabling us to demonstrate not only the vortex and dicrotic notch phenomenon but also the backflow and reverse pressure effect. Furthermore, it offers a generalized framework to realize extensive aortic valve conditions.

Antenna source of radio-frequency emission in ion-proton pulsars

ABSTRACT The growth of a longitudinal or quasi-longitudinal Langmuir mode in the outward-moving beam of ions and protons that forms the open sector of an ion-proton pulsar magnetosphere radiates as an analogue of an end-fed high-impedance horizontal straight-wire antenna an integral number of half-waves in length. The radiation has, broadly, the energy flux, linear polarization, and spectral index that are widely observed: also, the notch phenomenon seen in some integrated pulse profiles occurs naturally. The new field of pulsar observations below 100 MHz may lead to productive tests of the radio emission mechanism.

KERNOHAN’S NOTCH PHENOMENON IN AN ACUTE COMPONENTED CHRONIC SUBDURAL HEMATOMA PATIENT: A CASE REPORT

Kernohan's notch phenomenon is a rare examination finding in cases diagnosed as an intracranial space-occupying lesion. The localization of the space-occupying lesion in this clinical status, which is considered as a sign of herniation, is on the opposite side of the predicted side. The most typical finding is motor deficit and mydriasis on the same side as the space-occupying lesion. A 61-year-old female patient was evaluated in the emergency department due to sudden loss of consciousness. Her neurological examination revealed anisocoria and right hemiparesis findings, including mydriasis in the right pupil. Cranial computed tomography examination revealed a large, acute component combined with chronic subdural hematoma in the right frontoparietal region and midline shift. Clinical and radiological findings were evaluated as Kernohan’s Notch Sign phenomenon. The patient, who was operated on urgently, was discharged on the 7th postoperative day without any neurological deficits.

Kernohan-Woltman notch phenomenon: an exceptional neurological picture?

IntroductionIpsilateral hemiparesis (IH) can be defined as a paradoxical dysfunction of the first motor neuron involving the extremities on the opposite side to that expected, given the location of the triggering intracranial pathology. Compression of the corticospinal tract (CSt) along its course through the contralateral cerebral peduncle against the free edge of the tentorium, known as the Kernohan-Woltman notch phenomenon (KWNP), represents the main cause of IH. MethodsThis retrospective study analyses a series of 12 patients diagnosed with IH secondary to KWNP treated at our institution, including a descriptive study of epidemiological, clinical, radiological, neurophysiological, and prognostic variables. ResultsIn 75% of the cases, symptoms had an acute or subacute onset. Initial imaging studies showed signs of significant mass effect in half of the patients, whereas magnetic resonance imaging (MRI) identified a structural lesion in the contralateral cerebral peduncle in two thirds of them. Impairment of the motor evoked potentials (MEP) was verified in 4 patients. During follow-up 7 patients experienced improvement in motor activity, and near half of the cases were classified in the first three categories of the modified Rankin scale. ConclusionsIn contrast to prior historical series, most of our patients developed a KWNP secondary to a traumatic mechanism. MRI represents the optimal method to identify both the classic cerebral peduncle notch and the underlying structural lesion of the CSt. The use of MEP can help to establish the diagnosis, especially in those cases lacking definite radiological findings.

A case of Kernohan-Woltman notch phenomenon caused by an epidural hematoma: the diagnostic and prognostic value of PET/CT imaging

BackgroundKernohan-Woltman notch phenomenon (KWNP) classically occurs when a lesion causes compression of the contralateral cerebral peduncle against the tentorium, resulting in ipsilateral hemiparesis. It has been studied clinically, radiologically and electrophysiologically which all confirmed to cause false localizing motor signs. Here, we demonstrate the potential use of fluorine-18 fluorodeoxyglucose (18 F-FDG) positron emission tomography/computed tomography (PET/CT) to identify KWNP caused by an epidural hematoma.Case presentationA 29-year-old male patient post right-sided traumatic brain injury presenting with persistent ipsilateral hemiparesis. Patient underwent decompressive craniotomy and intracranial hematoma evacuation. Brain magnetic resonance imaging in the postoperative period showed a subtle lesion in the left cerebral peduncle. PET/CT was performed to exclude early brain tumor and explain his ipsilateral hemiparesis. PET/CT imaging demonstrated a focal region of intense 18 F-FDG uptake in the left cerebral peduncle. Throughout the treatment in outpatient neurorehabilitation unit, the patient exhibited a gradual recovery of his right hemiparesis.ConclusionIn our case report, for the first time, PET/CT offered microstructural and functional confirmation of KWNP. Moreover, our case suggests that 18 F-FDG PET/CT may serve as an important reference for the probability of functional recovery.

The Kernohan-Woltman Notch Phenomenon : A Systematic Review of Clinical and Radiologic Presentation, Surgical Management, and Functional Prognosis.

The Kernohan-Woltman notch phenomenon (KWNP) refers to an intracranial lesion causing massive side-to-side mass effect which leads to compression of the contralateral cerebral peduncle against the free edge of the cerebellar tentorium. Diagnosis is based on “paradoxical” motor deficit ipsilateral to the lesion associated with radiologic evidence of damage to the contralateral cerebral peduncle. To date, there is scarce evidence regarding KWNP associated neuroimaging patterns and motor function prognostic factors. A systematic review was conducted on Medline database from inception to July 2021 looking for English-language articles concerning KWNP, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The research yielded 45 articles for a total of 51 patients. The mean age was 40.7 years-old and the male/female sex ratio was 2/1. 63% of the patients (32/51) suffered from head trauma with a majority of acute subdural hematomas (57%, 29/51). 57% (29/51) of the patients were in the coma upon admission and 47% (24/51) presented pupil anomalies. KWNP presented the neuroimaging features of compression ischemic stroke located in the contralateral cerebral peduncle, with edema in the surrounding structures and sometimes compression stroke of the cerebral arteries passing nearby. 45% of the patients (23/51) presented a good motor functional outcome; nevertheless, no predisposing factor was identified. A Glasgow coma scale (GCS) of more than 3 showed a trend (p=0.1065) toward a better motor functional outcome. The KWNP is a regional compression syndrome oftentimes caused by sudden and massive uncal herniation and leading to contralateral cerebral peduncle ischemia. Even though patients suffering from KWNP usually present a good overall recovery, patients with a GCS of 3 may present a worse motor functional outcome. In order to better understand this syndrome, future studies will have to focus on more personalized criteria such as individual variation of tentorial notch width.

The Impact of Inverter Dead-Time in Single-Phase Wireless Power Transfer Systems

In this article, the effect of the dead-time on a single-phase wireless power transfer (WPT) system is studied in detail. In practice, the dead-time is always placed between the complementary switching pulses of the inverter phase-leg. At higher operating frequencies, the dead-time issues in the resonant inverter become critical, especially as the power level increases. The detailed analysis of the dead-time on a WPT system is discussed for different operating conditions of the inverter duty-cycle and power factor. The switching characteristics of the WPT system inverter are analyzed, and the notch phenomenon that appears at the output of the inverter is also discussed. A notch equation based on the observations is derived to predict the notch occurrence during the system operation. Furthermore, the mathematical expressions are presented for different notch conditions. Subsequently, the effect of the notches on the sensitivity and the power transfer of the series–series compensated WPT system is analyzed. Finally, the approach is verified experimentally on an 8-kW WPT system prototype, and the results are compared with the theoretical analysis.

스코트 변압기 적용 3상 계통의 불평형 전류보상 기법 연구

This paper presents a control algorithm using a Scott transformer to solve the imbalance problem in the three-phase system. Due to the imbalance of the three-phase system, the power system has a deterioration in quality. Here, a power compensation system is designed according to the actual driving environment of railway vehicles. The received three-phase AC power is converted into two single-phase power with a phase difference of 90 degrees through the Scott transformer, and the two loads are connected through a back-to-back converter. In order to minimize the power loss in the system, the back-to-back converter adopts a single three-level NPC converter. This compensation system uses the single-phase current on the secondary side of the Scott transformer for control. In order to solve the problem of voltage distortion caused by the notch phenomenon and phase tracking caused by the leakage inductance of the transformer when directly measuring the voltage on the single-phase side, an observer is cited. In order to verify the performance of the proposed current compensation system, simulations and experiments are carried out under the conditions of switching frequency of 600Hz, M-phase 5kW and T-phase 1kW imbalanced load. The experimental results show that the three-phase current unbalance rate after the current compensator is running has dropped from 67.99% to 0.58%, which fully verifies the excellent performance of the current compensator proposed in this paper.

An optoelectronic notch (‘dip’) phenomenon in the heterodyne photocarrier radiometry frequency response of Si wafers: a route to quantitative trap-state dynamic processes in semiconductors

An anomaly was observed in the heterodyne photocarrier radiometry (HePCR) frequency response of Si wafers in the form of a signal amplitude depression (‘dip’) accompanied by a 180° phase transition. This phenomenon resembles an electronic notch filter and was investigated experimentally and theoretically by invoking free-carrier-density-wave (CDW) kinetics in generic semiconductor systems. Both homodyne PCR and HePCR signals were obtained from n- and p-type wafers of different resistivities. Dynamic nonlinear rate-equation models with two bandgap carrier traps were introduced and analytical zeroth and first-order CDW solutions were obtained in the frequency domain. The experimental frequency responses of the HePCR optoelectronic notch phenomenon were found to be in very good agreement with the theory. Characteristic CDW recombination and trap capture and emission characteristic times were obtained and studied as functions of the illuminating laser intensity. The present newly observed HePCR notch phenomenon has revealed a new mechanism of nonlinear contributions due to trap-state-related CDW dynamics in semiconductors superposed on the well-known nonlinear electron-hole recombination interactions that give rise to non-zero HePCR signals. The implications of this notch phenomenon are discussed in terms of its importance in providing physical insights into photocarrier dynamic interactions with traps, leading to identification of active CDW trap-state numbers and precision measurements of their kinetic parameters, carrier capture and emission coefficients, and quantitative trap densities that determine the optoelectronic quality of semiconductors.

A Puzzling Exam: Kernohan’s Notch Reimaged

•We provide a visual image of the consequeces of massive brainstem shift with oculomotor and peduncle injury.•Acute space occupying lesions may cause ipsilateral hemiparesis – and can be a false localizing sign. Conventional teaching on the neurologic examination suggests findings can be attributed to specific regions – which improves timely diagnosis and treatment, particularly in life threatening situations. Rarely, puzzling patient presentations can wrongly lead to false localization. A 36-year-old man was found comatose. Head CT demonstrated an acute right convexity subdural hematoma, causing a nearly 2 cm midline shift. Initial neurologic examination was confounded by paralytic agents; however, there was a dilated-light fixed right pupil. The patient was taken for a right hemicraniectomy and hematoma evacuation (Fig. 1). Post-operative examination demonstrated right-sided oculomotor palsy and hemiplegia with preserved left-sided strength—consistent with a false localizing sign. An MRI on POD#1 revealed abnormal T2-signal hyperintensity involving the left anterolateral midbrain and cerebral peduncle, indicative of compression of the contralateral crus cerebri against the contralateral tentorial incisura (“notch”). The descending corticospinal tracts travel from the motor cortex through the ipsilateral crus cerebri into the inferior brainstem where they decussate-transmitting motor stimuli to the contralateral hemibody. Correspondingly, right-sided lesions above the decussation produce left-sided deficits. In the present case, the expected deficits would have been in the left hemibody. However, in rare circumstances involving a significant midline shift the contralateral peduncle is injured via compression at the tentorium. The oculomotor at the same side of the hematoma is as expected and either caused by strech of the nerve or direct compression of the uncus. This false localizing sign has been honored by the eponym "Kernohans Notch"..[[1]Kernohan J.W. Woltman H.W. Incisura of the crus due to contralateral brain tumor.Arch NeurPsych. 1929; 21: 274-287https://doi.org/10.1001/archneurpsyc.1929.02210200030004Crossref Scopus (117) Google Scholar] More deserving of the distinction is Groeneveld [[2]Dammers R Volovci V and Kompanje EJOThe History of the Kernohan Notch Revisited.Neurosurgery. 2016; 78: 581-584https://doi.org/10.1227/NEU.0000000000001097Crossref PubMed Scopus (0) Google Scholar] and Schaltenbrand who explained the injury as a knife-like stab (“Messerähnlichen Wirkung”) from the tentorium and possibly petrosal bone. There is a fascination with the Kernohan's notch phenomenon as evidenced by an ongoing flurry of case reports in the literature. Our patient clearly visualizes what has previously only been described in text and provides better proof of its existance. Picture Quiz: A 36 year-old male found down is noted on neurologic examination to have right hemiplegia and right oculomotor nerve palsy, with intact left upper and lower extremity function. Based on the exam, what is the most likely level of the lesion? A. Left motor cortex B. Right basal ganglia C. Left cerebral peduncle D. Right upper medulla Answer on page 336. LPC, AP, RCP, PCR, JLF, and EFW all provided substantial direct medical or surgical care pertaining to the diagnosis and treatment of the patient; LPC, AP, and CSG gathered the data and wrote manuscript/created the figure, PJR obtained formal patient consent and edited the manuscript, JLF and EFW supervised the project and made final manuscript editorial edits and approvals. None. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. A Puzzling Exam: Kernohan’s Notch ReimagedJournal of Clinical NeuroscienceVol. 80PreviewThe Answer is: C. Left cerebral peduncle. Full-Text PDF

Neuro-images Kernohan–Woltman notch phenomenon in acute subdural hematoma

Neuro-images Kernohan–Woltman notch phenomenon in acute subdural hematoma