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2.
RSC Adv ; 12(53): 34393-34403, 2022 Nov 29.
Article in English | MEDLINE | ID: mdl-36545611

ABSTRACT

Activated carbon as a low-cost adsorbent prepared from almond shells using H3PO4 as a chemical activator and room vacuum pyrolysis as a physical activator, which is considered to be an eco-compatible preparation process. Experimental design methodology was used to study and optimize the effects of eight preparation parameters on I2 adsorption expressed by the iodine index (mg g-1). It was found that optimum activated carbon was obtained by chemical activation with H3PO4 at first, followed by physical treatment at 420 °C under a vacuum pressure of -0.8 bar. The obtained activated carbon was characterized by a thermogravimetric analyzer, scanning electron microscopy coupled to EDX, X-ray diffraction, and Fourier transform infrared absorption spectroscopy. The zero-charge pH and the characteristics of surface chemistry by Boehm titration were determined to predict the acid-base properties of the prepared material. An adsorption efficiency study of crystal violet dye on the optimally produced activated carbon was carried out. The obtained results of physicochemical characterization showed interesting properties of our activated carbon in comparison with those produced by other methods. Among these properties, an important porous surface, high thermal stability, and a disorganized graphitic crystalline structure were revealed. In addition to the carbon and oxygen elements, EDX analysis revealed the presence of phosphorus element, and the FTIR analysis indicated the existence of phosphonate groups and an acidic character, which resulted from chemical activation by H3PO4. An iodine index of 824.85 mg g-1 was achieved for optimal preparation. Crystal violet adsorption studies show a pseudo-first-order kinetic process and fit well with the Freundlich isotherm model, and thus, the predicted adsorption capacity was 364.27 mg g-1.

3.
Appl Radiat Isot ; 166: 109384, 2020 Dec.
Article in English | MEDLINE | ID: mdl-32980766

ABSTRACT

Gamma-ray spectrometry logs are verified as a qualitative analysis tool for clay minerals where clay swelling depends on the clay mineral type. The data are obtained from three random wells (Kh-24, Bassel-1X, and Hayat-1X wells) in Western Desert oil fields. X-ray diffraction, scanning electron microscopy, and gamma-ray spectrometry are performed and the swelling potential index is obtained for surface samples from the Bahariya Formation. The swelling values and the total counts of gamma radiation, equivalent Th, equivalent U, and K are plotted with correlation coefficients (r) of 0.71, 0.81, 0.62, and 0.07, respectively. The swelling percentage ranges from 33% to 110%. This swelling behavior is reflected in the great difference in the composition of the clay minerals. Active clay minerals such as montmorillonite are widely observed with mixed-layer clay, illite, chlorite, and kaolinite. The correlation coefficients clarify a strong relation occurs in the cases of total gamma radiation and equivalent Th versus the swelling index. Consequently, gamma-ray spectrometry logs provide a new approach for identifying not only clay minerals but also their swelling trend. Moreover, they help to give an expected drilling risk, such as stuck while drilling.

4.
Otol Neurotol ; 39(7): e561-e567, 2018 08.
Article in English | MEDLINE | ID: mdl-29912833

ABSTRACT

OBJECTIVE: To evaluate the relationship between normal and abnormal ocular vestibular evoked myogenic potentials (oVEMP) and cervical vestibular evoked myogenic potentials (cVEMP) in patients with and without vestibular migraine (VM). STUDY DESIGN: Retrospective review of oVEMP and cVEMP results in patients with vestibular disorders who were assessed clinically and completed vestibular function studies. Data were extracted from a deidentified RedCap Repository. SETTING: Tertiary care multispecialty medical center. PATIENTS: Subjects were 212 consecutive adults meeting prespecified inclusion criteria who were evaluated in the Balance Disorders Clinic at Vanderbilt University Medical Center between 2011 and 2017. Patients with bilaterally absent VEMPs were excluded from the study. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Proportions of subjects with or without VM in one of the following four test outcomes: normal cVEMP/normal oVEMP, abnormal cVEMP/abnormal oVEMP, abnormal cVEMP/normal oVEMP, and normal cVEMP/abnormal oVEMP. RESULTS: There was a significant relationship between VM and cVEMP and oVEMP test outcomes. CONCLUSION: Patients with VM are more likely than subjects with vestibular disorders other than migraine to exhibit normal cVEMP responses in the presence of unilaterally abnormal oVEMP responses. Such a VEMP pattern may be a biomarker of VM and further supports a possible pathophysiologic relationship between the utriculo-ocular reflex and VM.


Subject(s)
Migraine Disorders/physiopathology , Vestibular Diseases/physiopathology , Vestibular Evoked Myogenic Potentials/physiology , Adult , Female , Humans , Male , Middle Aged , Retrospective Studies
5.
Reumatismo ; 67(2): 68-77, 2015 Sep 16.
Article in English | MEDLINE | ID: mdl-26492965

ABSTRACT

Hip disorders in a pediatric population are a diagnostic challenge. The aim of the study is to assess the role of magnetic resonance imaging (MRI) in the evaluation of non-traumatic hip disorders in a series of Egyptian patients and to review the literature on the most common hip conditions. Seventy two consecutive patients [40 males (55.6%) and 32 females (44.4)] with acute onset of hip complaints unrelated to trauma or falls were recruited. All patients underwent an initial full clinical assessment and blood tests as well as contrast enhanced MRI of both hips. The most common diagnosis in this group of Egyptian patients was transient synovitis in 29 (40.3%) cases, followed by seronegative enthesopathy and arthropathy syndrome in 8 (11.1%), septic arthritis in 10 (13.9%), tuberculous arthritis in 4 (5.6%), sickle-cell disease in 7 (9.7%), complicated with septic arthritis in 3 (4.2%), transient bone marrow edema (BME) in 3 (4.2%), osteomyelitis in 2 (2.8%), osteosarcoma in 2 (2.8%), sciatic nerve injury in 1 (1.4%), leukemia with BME in 1 (1.4%), coxa vara of both hips and L5/S1 facet joint ankylosis in 1 (1.4%), and a benign bone cyst in 1 (1.4%). MRI studies showed hip effusion in a total of 51 patients (70.8%), joint space narrowing in 9 (12.5%), and BME in 15(20.8%). MRI is a sensitive tool for assessing hip disorders in a pediatric population and can play an important role in both diagnosis and management of different hip disorders, irrespective of the underlying pathology.


Subject(s)
Hip Joint/diagnostic imaging , Joint Diseases/diagnostic imaging , Magnetic Resonance Imaging , Anemia, Sickle Cell/complications , Arthritis/diagnostic imaging , Arthritis/epidemiology , Child , Child, Preschool , Comorbidity , Egypt/epidemiology , Enthesopathy/diagnostic imaging , Enthesopathy/epidemiology , Female , Follow-Up Studies , Hemarthrosis/diagnostic imaging , Hemarthrosis/epidemiology , Hemarthrosis/etiology , Humans , Joint Diseases/epidemiology , Male , Prospective Studies , Synovitis/diagnostic imaging , Synovitis/epidemiology
7.
Headache ; 53(6): 1028-9, 2013 Jun.
Article in English | MEDLINE | ID: mdl-23594065

ABSTRACT

Headache is a symptom of cerebrovascular disease, particularly the hemorrhagic type. Also, certain headache types, notably migraine with aura, predispose individuals to ischemic and perhaps hemorrhagic stroke. The relationship between migraine and cerebrovascular disease can be causal, coincidental or co-morbid.


Subject(s)
Headache/diagnosis , Headache/epidemiology , Migraine Disorders/diagnosis , Migraine Disorders/epidemiology , Stroke/diagnosis , Stroke/epidemiology , Animals , Humans
8.
Appl Radiat Isot ; 73: 90-5, 2013 Mar.
Article in English | MEDLINE | ID: mdl-23306160

ABSTRACT

Petroleum oil is an important source for the energy in the world. The Gulf of Suez, Nile Delta and South Valley are important regions for studying hydrocarbon potential in Egypt. A thorium normalization technique was applied on the sandstone reservoirs in the three regions to determine the hydrocarbon potentialities zones using the three spectrometric radioactive gamma ray-logs (eU, eTh and K% logs). The conventional well logs (gamma-ray, deep resistivity, shallow resistivity, neutron, density and sonic logs) are analyzed to determine the net pay zones in these wells. Indices derived from thorium normalized spectral logs indicate the hydrocarbon zones in petroleum reservoirs. The results of this technique in the three regions (Gulf of Suez, Nile Delta and South Valley) are in agreement with the results of the conventional well log analyses by ratios of 82%, 78% and 71% respectively.

9.
Appl Radiat Isot ; 73: 68-73, 2013 Mar.
Article in English | MEDLINE | ID: mdl-23291561

ABSTRACT

A 3D block of radiogenic heat production was constructed from the subsurface total gamma ray logs of Bahariya Formation, Western Desert, Egypt. The studied rocks possess a range of radiogenic heat production varying from 0.21 µWm(-3) to 2.2 µWm(-3). Sandstone rocks of Bahariya Formation have higher radiogenic heat production than the average for crustal sedimentary rocks. The high values of density log of Bahariya Formation indicate the presence of iron oxides which contribute the uranium radioactive ores that increase the radiogenic heat production of these rocks. The average radiogenic heat production produced from the study area is calculated as 6.3 kW. The histogram and cumulative frequency analyses illustrate that the range from 0.8 to 1.2 µWm(-3) is about 45.3% of radiogenic heat production values. The 3D slicing of the reservoir shows that the southeastern and northeastern parts of the study area have higher radiogenic heat production than other parts.

10.
Headache ; 49(10): 1423-34, 2009.
Article in English | MEDLINE | ID: mdl-19751370

ABSTRACT

BACKGROUND: MAP0004 is a novel orally inhaled formulation of dihydroergotamine mesylate (DHE) currently in development that has been clinically observed to provide rapid ( approximately 10 minutes) therapeutic levels of DHE but with lower rates of adverse effects (dizziness, nausea, and paresthesia) compared with intravenous (IV) dosing. Receptor-based mechanistic studies were conducted to determine if differences between IV DHE and inhaled DHE (MAP0004) binding and functional activity were responsible for the improved adverse event profile. METHODS: Radioligand competitive binding assays were performed at adrenergic (alpha1 [non-specific], alpha2A, alpha2B, alpha2C, beta), dopaminergic (D; D(1), D(2), D(3)), and at serotonergic (5-HT; 5-HT(1A), 5-HT(1B), 5-HT(1D), 5-HT(2A), 5-HT(2C), 5-HT(3), 5-HT(4), 5-HT(5A), 5-HT(6), 5-HT(7)) receptors. Binding assays were also conducted for the major metabolite of DHE, 8'-hydroxy-DHE (8'-OH-DHE). Subsequent functional receptor assays were also performed at 5-HT(1B), 5-HT(1D), 5-HT(2A), 5-HT(2C), 5-HT(3), D(2), alpha1A, alpha2A, alpha2B, beta1, and beta2 and muscarinic receptors to ensure that observed receptor binding translated into potential functional response. RESULTS: For competitive binding studies, DHE demonstrated extensive activity at IV C(max) for all 5-HT receptors tested, except 5-HT(3) and 5-HT(4), and alpha1, alpha2A, alpha2B, alpha2C, and D(3) receptors. DHE concentrations used in the studies were equal to the peak plasma concentrations (C(max)) observed in human subjects following IV DHE 1.0 mg (the standard approved dose), and 2 and 4 inhalations MAP0004 which, respectively, produced systemic circulation levels of DHE equivalent to 0.44 mg and 0.88 mg administered IV. MAP0004 binding activity at the C(max) concentrations was lower than IV DHE and no binding was observed for the 8'-OH-DHE metabolite. However, MAP0004 preserved potent agonist action at key anti-migraine 5-HT(1B) and 5-HT(1D) receptors, even at the lower C(max )concentrations. Functional binding studies displayed similar results whereby IV DHE C(max) concentrations invoked strong agonist/antagonist responses, for instance at adrenergic and 5-HT(2C) receptors, which could have been responsible for dizziness. Conversely, at C(max) concentrations of MAP0004, inhaled DHE achieved a significantly lower response or no response at the adrenergic and 5-HT(2C) receptors. CONCLUSIONS: The mechanism by which nausea was experienced with IV DHE--yet not with MAP0004--was not associated with classic nausea pathways/targets (dopamine, 5-HT(3), or muscarinic receptors) or with peripheral action in the intestine via enterochromaffin cells. Importantly, the maximum DHE concentrations following MAP0004 administration were insufficient to interact with receptors implicated in cardiovascular (5-HT(2B) and beta(1)) and pulmonary effects (beta(2), adenosine, muscarinic, and leukotriene).


Subject(s)
Dihydroergotamine/administration & dosage , Dihydroergotamine/adverse effects , Administration, Inhalation , Administration, Oral , Animals , Cross-Over Studies , Dizziness/chemically induced , Dizziness/metabolism , Guinea Pigs , Humans , Infusions, Intravenous , Nausea/chemically induced , Nausea/metabolism , Protein Binding/physiology , Receptors, Serotonin/metabolism
11.
Headache ; 48(3): 355-67, 2008 Mar.
Article in English | MEDLINE | ID: mdl-18179563

ABSTRACT

OBJECTIVE: We investigated the pulmonary absorption of dihydroergotamine (DHE) mesylate and compared the safety, pharmacokinetic, and metabolic profile of 4 different doses of orally inhaled DHE delivered by the Tempo Inhaler (MAP Pharmaceuticals Inc., Mountain View, CA, USA) with 1.0 mg intravenously (IV) administered DHE in 18 healthy subjects. METHODS: Safety was measured by monitoring adverse events, vital signs, electrocardiograms, spirometry, and changes in biochemical and hematological laboratory values. Liquid chromatography, tandem mass spectrometry was used to determine plasma DHE levels while C(max), t(max), AUC(0-6), AUC(0-48), AUC(0-inf), and t(1/2) of parent DHE and the major bioactive metabolite, 8'OH-DHE. Pharmacokinetic parameters and qualitative spectrograms for DHE and metabolites for all treatment groups were compared after inhaled DHE (MAP0004) and IV DHE 1.0 mg. Geometric means and 90% confidence intervals of log-transformed data were calculated and the ratio of means compared. RESULTS: Inhaled DHE resulted in rapid systemic absorption with pharmacokinetic parameters of both parent DHE and 8'OH-DHE similar to those achieved after a 3-minute IV infusion. Post-peak (t(max) approximately 12 minutes) DHE concentrations achieved after 4 actuations ( approximately 0.88 mg respirable dose) of MAP0004 were comparable to those detected after IV administration. The systemic exposure to DHE after 6 actuations of MAP0004 was slightly greater than that achieved after IV administration (geometric mean AUC(0-inf) ratio = 1.24). CONCLUSION: The 4-actuation delivery was well tolerated and provided systemic levels of DHE and 8'OH-DHE slightly lower than IV administration and predicted levels.


Subject(s)
Analgesics, Non-Narcotic/adverse effects , Analgesics, Non-Narcotic/pharmacokinetics , Dihydroergotamine/adverse effects , Dihydroergotamine/pharmacokinetics , Metered Dose Inhalers , Administration, Inhalation , Adult , Analgesics, Non-Narcotic/administration & dosage , Area Under Curve , Dihydroergotamine/administration & dosage , Dose-Response Relationship, Drug , Female , Humans , Male
12.
Headache ; 47 Suppl 1: S52-7, 2007 Apr.
Article in English | MEDLINE | ID: mdl-17425710

ABSTRACT

A variety of drugs from diverse pharmacological classes are in use for migraine prevention. Traditionally, they have been discovered by serendipity. Examples include beta-adrenergic blockers, anticonvulsants, tricyclic antidepressants, and serotonin receptor antagonists. The mechanisms of action of migraine preventive drugs are multiple but it is postulated that they converge on two targets: (1) inhibition of cortical excitation; (2) restoring nociceptive dysmodulation. The antiepileptic drugs (e.g., topiramate, valproate, gabapentin), calcium channel blockers such as verapamil, and inhibitors of cortical spreading depression are some examples of drugs that reduce neuronal hyperexcitability. On the other hand, modulators of the serotonergic and adrenergic systems and cholinergic enhancing drugs may restore descending nociceptive inhibition and play a role in migraine prevention. To date, Level 1 evidence and clinical experience favor the use of the antidepressant amitriptyline, the anticonvulsants divalproex and topiramate, and the beta-adrenergic blockers propranolol, timolol and metoprolol as first line migraine preventive drugs. The evidence for others (e.g., verapamil) is not as strong. Migraine preventive drugs have varying degrees of adverse effects, some of which could be limiting, and their efficacy should balanced with their risks of adverse effects, patients' expectations and desires, and compliance. It is hoped that future migraine preventive drugs target migraine mechanisms more specifically, which could well enhance the therapeutic index.


Subject(s)
Migraine Disorders/drug therapy , Migraine Disorders/prevention & control , Adrenergic beta-Antagonists/therapeutic use , Anti-Inflammatory Agents, Non-Steroidal/therapeutic use , Anticonvulsants/therapeutic use , Antidepressive Agents, Tricyclic/therapeutic use , Cerebral Cortex/physiopathology , Cyclooxygenase Inhibitors/therapeutic use , Drug Therapy/trends , Humans , Migraine Disorders/physiopathology , Nociceptors/physiopathology , Serotonin Antagonists/therapeutic use
13.
Hum Mutat ; 28(5): 522, 2007 May.
Article in English | MEDLINE | ID: mdl-17397047

ABSTRACT

Familial hemiplegic migraine (FHM) is a severe subtype of migraine with hemiparesis during attacks. We scanned 10 families with FHM without mutations in the CACNA1A (FHM1) and ATP1A2 (FHM2) genes. We identified the novel p.L1649Q mutation (c.4946T>A) in Na(v)1.1 sodium channel gene SCN1A (FHM3) in a North American kindred with FHM without associated ataxia or epilepsy. Functional analysis of the mutation, introduced in the highly homologous human SCN5A, revealed markedly slowed inactivation and a two-fold faster recovery from fast inactivation predicting enhanced neuronal excitation. Our findings establish the role of neuronal Na(v)1.1 sodium channels in FHM and reinforce the involvement of ion channel dysfunction in the pathogenesis of this episodic brain disorder.


Subject(s)
Epilepsy/genetics , Migraine Disorders/genetics , Mutation , Nerve Tissue Proteins/genetics , Sodium Channels/genetics , Cells, Cultured , Genetic Carrier Screening , Humans , Mutagenesis , NAV1.1 Voltage-Gated Sodium Channel , Polymerase Chain Reaction
14.
Pharmacol Ther ; 112(1): 199-212, 2006 Oct.
Article in English | MEDLINE | ID: mdl-16797716

ABSTRACT

Modern neuroscience advanced our understanding of putative migraine mechanisms, which led to improved therapeutics. Indeed, mechanism-based acute migraine therapy gained steam in the early 1990s after the introduction of the triptans (5-HT1B,D agonists). Post-triptans, novel targets such as calcitonin gene-related peptide (CGRP) antagonists, inhibitors of excitatory glutamatergic receptors, and nitric oxide synthase (NOS) inhibitors are leading the pack in this exploding field of discovery research. In contrast, novel therapeutic targets for migraine prevention are lacking despite a hugely unmet need. To date, migraine prophylactic drugs are advanced based on expanded indications for already approved pharmaceuticals (e.g., topiramate, valproate, propranolol, and timolol). An improved understanding of the predisposition to an attack, genomic discoveries, valid and reliable biomarkers and surrogates, and predictive preclinical models likely will unravel the neuronal substrates for central hyperexcitability and nociceptive dysmodulation, hopefully leading us to better mechanism-based targets for prevention, and ultimately yielding drugs with optimal therapeutic ratios or indices.


Subject(s)
Migraine Disorders/drug therapy , Humans , Migraine Disorders/prevention & control
15.
Aviat Space Environ Med ; 77(5): 509-14, 2006 May.
Article in English | MEDLINE | ID: mdl-16708531

ABSTRACT

BACKGROUND: Technological advances in military equipment have resulted in more devices being mounted on the helmet to enhance the capability of the soldier. The soldier's neck must bear this head-supported mass (HSM) and the resulting dynamic characteristics of the head and neck system are changed. The purpose of this study was to vary the conditions of impact as well as the design criteria to quantify the effect of HSM on neck injury risk through computational modeling. METHODS: The TNO MADYMO detailed neck model was used for a matrix of 196 simulations designed to vary the impact conditions and HSM properties added to the model. These parameters included seven impact directions, three impact magnitudes, nine mass locations, and three mass magnitudes. The data collected from these simulations were evaluated for injury risk using the lower neck beam criterion equation. RESULTS: The results from these simulations provide detailed information regarding the risk of injury based on a particular HSM configuration and the acceleration of the body. The predominant factor in increasing risk in the lower neck is the increase in pulse magnitude. The effect of pulse magnitude is more dominant in the directions that create a flexion or lateral bending moment. CONCLUSION: HSM increases the level of injury, but the impact level that the subject is exposed to is a more dominating factor in determining injury risk.


Subject(s)
Computer Simulation , Head/physiology , Models, Biological , Neck Injuries/physiopathology , Neck/physiology , Aerospace Medicine , Head Protective Devices , Humans , Military Medicine , Weight-Bearing/physiology
16.
Semin Neurol ; 26(2): 157-62, 2006 Apr.
Article in English | MEDLINE | ID: mdl-16628525

ABSTRACT

Clinical diagnostic classifications are critical when clear biological markers are not available. Such is the case in many headache disorders and mental disorders. Also, it is crucial that the classification is widely accepted and utilized. A main goal of classification is to be a universal language for categorizing a disease or a set of disorders, establishing diagnostic criteria, and promoting unity in treatment. The International Headache Society published its first Classification of Headache Disorders in 1988 and its second edition in 2004. The first classification paved the way for a better understanding of the epidemiology, mechanisms, and treatment of headache disorders, and the second edition likely will magnify our knowledge. This article provides an overview of the classification system and outlines some of the major changes in the revised edition.


Subject(s)
Headache Disorders/classification , Diagnosis, Differential , Headache Disorders/diagnosis , Headache Disorders/history , History, 20th Century , History, 21st Century , Humans , International Classification of Diseases
17.
Semin Neurol ; 26(2): 188-98, 2006 Apr.
Article in English | MEDLINE | ID: mdl-16628529

ABSTRACT

Migraine therapeutics are pharmacological, including acute and preventive, nonpharmacological and/or both. Preventive pharmacological strategies serendipitously were discovered to be effective and include drugs from various pharmacological classes (e.g., beta-adrenergic blocker, anticonvulsant, tricyclic antidepressants, serotonin receptor antagonist). Converging level I evidence and clinical experience support the use of the antidepressant amitriptyline, the anticonvulsants divalproex and topiramate, and the beta-adrenergic blockers propranolol, timolol, and metoprolol in migraine prevention. Other options for migraine prophylaxis exist, but the level of evidence in support of their use is not as robust. All of these drugs have varying degrees of adverse effects, some of which can limit their use. Balancing potential efficacy with risk of adverse effects, addressing patients' expectations and desires, complying with management recommendations, adequate follow up, and accurate assessment of treatment goals are key to migraine prevention. Finally, future migraine-preventive drugs likely will target migraine mechanisms more specifically, which undoubtedly will enhance the therapeutic index.


Subject(s)
Drug Therapy/methods , Migraine Disorders/prevention & control , Adrenergic Agents/therapeutic use , Angiotensins/agonists , Angiotensins/antagonists & inhibitors , Antidepressive Agents/therapeutic use , Calcium Channel Blockers/therapeutic use , Humans , Neurotoxins/therapeutic use , Neurotransmitter Agents/therapeutic use , Serotonin Antagonists/therapeutic use
18.
Curr Neurol Neurosci Rep ; 6(2): 95-9, 2006 Mar.
Article in English | MEDLINE | ID: mdl-16522261

ABSTRACT

Migraine is increasingly recognized as a disorder of altered neuronal excitability, in part based on genetically mediated and environmentally modified aberrations of ionic exchange across the brain neuronal membrane. To this end, migraine pharmacotherapy aids in restoring the abnormally low threshold for neuronal excitation. Indeed, modulation of neuronal excitability is a common property of several established migraine preventive drugs such as propranolol, valproate, amitriptyline, and topiramate. Future migraine preventive pharmacologic therapies likely will aim at restoring the neuronal threshold for excitation by targeting such processes as cortical spreading depression and intracellular calcium influx. Also, strategies aimed at enhancing descending antinociceptive inhibition will yield effective antimigraine drugs.


Subject(s)
Migraine Disorders/prevention & control , Guidelines as Topic , Humans
20.
J Am Acad Audiol ; 15(4): 324-33, 2004 Apr.
Article in English | MEDLINE | ID: mdl-15239205

ABSTRACT

Velocity storage (VS), a brainstem function, extends the low-frequency response of the vestibular system. To better understand VS mechanisms and characteristics in humans, we analyzed retrospectively functional measures of gait, electrophysiological measures of vestibular function, and imaging studies in an attempt to determine clinical, electrophysiological, and anatomical correlates of abnormalities in VS. Two cohorts of patients referred to our Risk of Falls Assessment Clinic participated in this investigation. Group 1 (control) patients demonstrated normal caloric and rotary chair tests. Group 2 patients with impaired velocity storage (experimentals) differed clinically from Group 1 only by demonstrating abnormal multifrequency vestibulocular reflex phase measures on rotational testing. Results showed that Group 2 patients had greater impairments in postural stability and gait than Group 1 patients. Additionally, 80% of patients in Group 2 and none in Group 1 showed pontine hyperintense lesions on MRI.


Subject(s)
Brain Stem/pathology , Gait/physiology , Postural Balance/physiology , Vestibular Diseases/physiopathology , Vestibule, Labyrinth/physiology , Aged , Aged, 80 and over , Brain Ischemia/pathology , Brain Ischemia/physiopathology , Brain Stem/anatomy & histology , Brain Stem/blood supply , Case-Control Studies , Cohort Studies , Dizziness/physiopathology , Electronystagmography , Female , Humans , Magnetic Resonance Imaging , Male , Middle Aged , Reflex, Vestibulo-Ocular/physiology , Retrospective Studies , Vestibular Function Tests , Vestibule, Labyrinth/anatomy & histology , Vestibulocochlear Nerve/physiology
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