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Theofilos G. Machinis, Kostas N. Fountas, Vassilios Dimopoulos and Joe Sam Robinson

The purpose of this article is to provide insight into the development of surgery for acoustic neurinomas throughout the years. The significant contribution of surgical authorities such as Cushing, Dandy, and House are discussed. The advances in surgical techniques from the very first operations for acoustic tumors at the end of the 19th century until today are described, with special emphasis on the technological and diagnostic milestones that preceded each step of this development.

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Ioannis Siasios, Eftychia Z. Kapsalaki, Kostas N. Fountas, Aggeliki Fotiadou, Alexander Dorsch, Kunal Vakharia, John Pollina and Vassilios Dimopoulos


Diffusion tensor imaging (DTI) for the assessment of fractional anisotropy (FA) and involving measurements of mean diffusivity (MD) and apparent diffusion coefficient (ADC) represents a novel, MRI-based, noninvasive technique that may delineate microstructural changes in cerebral white matter (WM). For example, DTI may be used for the diagnosis and differentiation of idiopathic normal pressure hydrocephalus (iNPH) from other neurodegenerative diseases with similar imaging findings and clinical symptoms and signs. The goal of the current study was to identify and analyze recently published series on the use of DTI as a diagnostic tool. Moreover, the authors also explored the utility of DTI in identifying patients with iNPH who could be managed by surgical intervention.


The authors performed a literature search of the PubMed database by using any possible combinations of the following terms: “Alzheimer's disease,” “brain,” “cerebrospinal fluid,” “CSF,” “diffusion tensor imaging,” “DTI,” “hydrocephalus,” “idiopathic,” “magnetic resonance imaging,” “normal pressure,” “Parkinson's disease,” and “shunting.” Moreover, all reference lists from the retrieved articles were reviewed to identify any additional pertinent articles.


The literature search retrieved 19 studies in which DTI was used for the identification and differentiation of iNPH from other neurodegenerative diseases. The DTI protocols involved different approaches, such as region of interest (ROI) methods, tract-based spatial statistics, voxel-based analysis, and delta-ADC analysis. The most studied anatomical regions were the periventricular WM areas, such as the internal capsule (IC), the corticospinal tract (CST), and the corpus callosum (CC). Patients with iNPH had significantly higher MD in the periventricular WM areas of the CST and the CC than had healthy controls. In addition, FA and ADCs were significantly higher in the CST of iNPH patients than in any other patients with other neurodegenerative diseases. Gait abnormalities of iNPH patients were statistically significantly and negatively correlated with FA in the CST and the minor forceps. Fractional anisotropy had a sensitivity of 94% and a specificity of 80% for diagnosing iNPH. Furthermore, FA and MD values in the CST, the IC, the anterior thalamic region, the fornix, and the hippocampus regions could help differentiate iNPH from Alzheimer or Parkinson disease. Interestingly, CSF drainage or ventriculoperitoneal shunting significantly modified FA and ADCs in iNPH patients whose condition clinically responded to these maneuvers.


Measurements of FA and MD significantly contribute to the detection of axonal loss and gliosis in the periventricular WM areas in patients with iNPH. Diffusion tensor imaging may also represent a valuable noninvasive method for differentiating iNPH from other neurodegenerative diseases. Moreover, DTI can detect dynamic changes in the WM tracts after lumbar drainage or shunting procedures and could help identify iNPH patients who may benefit from surgical intervention.

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Vassilios Dimopoulos, Kostas N. Fountas, Theofilos G. Machinis, Carlos Feltes, Induk Chung, Kim Johnston, Joe Sam Robinson and Arthur Grigorian

Cauda equina syndrome is a well-documented complication of uneventful lumbar microdiscectomy. In the vast majority of cases, no radiological explanation can be obtained. In this paper, the authors report two cases of postoperative cauda equina syndrome in patients undergoing single-level de novo lumbar microdiscectomy in which intraoperative electrophysiological monitoring was used. In both patients, the amplitudes of cortical and subcortical intraoperative somatosensory evoked potentials (SSEPs) abruptly decreased during discectomy and foraminotomy. In the first patient, a slow, partial improvement of SSEPs was observed before the end of the operation, whereas no improvement was observed in the second patient. In the first case, clinical findings consistent with cauda equina syndrome were seen immediately postoperatively, whereas in the second one the symptoms developed within 1.5 hours after the procedure. Postoperative magnetic resonance images obtained in both patients, and a lumbar myelogram obtained in the second one revealed no signs of conus medullaris or nerve root compression. Both patients showed marked improvement after an intense course of rehabilitation. The authors' findings support the proposition that intraoperative SSEP monitoring may be useful in predicting the development of cauda equina syndrome in patients undergoing lumbar microdiscectomy. Nevertheless, further prospective clinical studies are necessary for validation of these findings.

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Angel N. Boev, Kostas N. Fountas, Ioannis Karampelas, Christine Boev, Theofilos G. Machinis, Carlos Feltes, Ike Okosun, Vassilios Dimopoulos and Christopher Troup


The authors describe the prospective use of a new hand-held point-and-shoot pupillometer (NeurOptics) to assess pupil function quantitatively.


Repetitive measurements were made in 90 pediatric participants ranging in age from 1 to 18 years, providing a total of 100 measurements under ambient light conditions. The participants consisted of 45 patients without known intracranial or ophthalmological pathological conditions as well as 45 volunteers in the outpatient setting. Quantitative pupil measurements were reliably replicated in the study participants. The mean resting pupil aperture was 4.11 mm and the minimal diameter after stimulation was 2.65 mm, resulting in a 36% change in pupil size. The mean constriction velocity was 2.34 mm/second, with a mean dilation velocity of 2.2 mm/second.


Pupil symmetry was impressive in the entire cohort.

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Carlos Feltes, Kostas N. Fountas, Theofilos Machinis, Leonidas G. Nikolakakos, Vassilios Dimopoulos, Rostislav Davydov, Mozaffar Kassam, Kim W. Johnston and Joe Sam Robinson


Painful osteoporotic vertebral compression fractures (VCFs) are a significant cause of disability in the elderly population. Kyphoplasty, a recently developed minimally invasive procedure, has been advocated for the successful management of these fractures in terms of immediate pain relief, and also for restoration of the premorbid level of daily activities. In this retrospective study the authors report on their experience with the early management of VCFs with kyphoplasty.


A retrospective analysis was conducted in 13 patients (seven women and six men) whose ages ranged from 48 to 87 years (mean age 71.5 ± 11 years [mean ± standard deviation]). The interval between onset of symptoms and surgical intervention ranged from 4 to 9 weeks. Twenty levels (12 thoracic, eight lumbar) were treated in this cohort. Immediate and early postoperative (1-month follow-up visit) visual analog scale (VAS) pain scores, activity levels, and restoration of vertebral body (VB) height were assessed.

The mean preoperative VAS score was 8 ± 1, whereas the immediate and early postoperative scores were 1 ± 1. These findings reflected a resolution of 90 to 100% of preoperative pain. All patients resumed routine activities within hours of the procedure, although improvement in VB height was not accomplished in this cohort. No major complications were encountered in this clinical series.


Kyphoplasty is a safe and effective method for the treatment of osteoporotic VCFs. Failure to restore VB height does not seem to interfere with the excellent pain management and good functional outcome provided by this procedure.