Aristotelis S. Filippidis and Kostas N. Fountas
Efthimios Dardiotis, Kostas N. Fountas, Maria Dardioti, Georgia Xiromerisiou, Eftychia Kapsalaki, Anastasia Tasiou and Georgios M. Hadjigeorgiou
Traumatic brain injury (TBI) constitutes a major cause of mortality and disability worldwide, especially among young individuals. It is estimated that despite all the recent advances in the management of TBI, approximately half of the patients suffering head injuries still have unfavorable outcomes, which represents a substantial health care, social, and economic burden to societies.
Considerable variability exists in the clinical outcome after TBI, which is only partially explained by known factors. Accumulating evidence has implicated various genetic elements in the pathophysiology of brain trauma. The extent of brain injury after TBI seems to be modulated to some degree by genetic variants.
The authors' current review focuses on the up-to-date state of knowledge regarding genetic association studies in patients sustaining TBI, with particular emphasis on the mechanisms underlying the implication of genes in the pathophysiology of TBI.
Theofilos G. Machinis, Kostas N. Fountas, John Hudson, Joe Sam Robinson and E. Christopher Troup
Ventriculoatrial (VA) shunts remain a valid option for the treatment of hydrocephalus, especially in patients in whom ventriculoperitoneal (VP) shunts fail. Correct positioning of the distal end of the catheter in the right atrium is of paramount importance for maintaining shunt patency and reducing the incidence of VA shunt-associated morbidity. The authors present their experience with real-time transesophageal echocardiography (TEE) monitoring for the accurate placement of the distal catheter of a VA shunt.
Four patients underwent conversion of a VP shunt to a VA shunt under the guidance of intraoperative fluoroscopy and TEE between May 2003 and December 2004. After induction of general anesthesia, the TEE transducer was advanced into the esophagus. A cervical incision was made and the external jugular vein was visualized. An introducer was passed through an opening in the jugular vein and a guidewire was placed through the introducer. Under continuous TEE guidance, the guidewire was carefully advanced into the superior vena cava. A distal shunt catheter overlying a J-wire was then passed to the superior vena cava, again under TEE guidance. The catheter was advanced to the right atrium after removing the guidewire.
Final visualization with TEE and fluoroscopy revealed a good position of the catheter in the right atrium in all four cases. The mean duration of the operation was 91 minutes (range 65–120 minutes) and the mean operative blood loss was 23 ml (range 10–50 ml). No procedure-related complication was noted.
Real-time TEE is a safe and simple technique for the accurate placement of the distal catheter of a VA shunt.
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.
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.
Kostas N. Fountas, Robert S. Donner, Leonidas G. Nikolakakos, Carlos H. Feltes, Ioannis Karampelas and Joe Sam Robinson Jr.
✓ The authors report a unique case of diffuse spinal metastatic disease due to a pleomorphic rhabdomyosarcoma (RMS) in an adult. In additon to its overall rarity, peculiar characteristics of the particular tumor included its site of origin, demonstrated radiologically as the lumbar paravertebral musculature (psoas muscle) and the transcanalicular spread into the vertebral canal, resulting in thecal compression at multiple levels. The salient clinicopathological characteristics of RMS, as they related particularly to the spine, are subsequently discussed and a short review of the major therapeutic modalities for these tumors is offered.
Kostas N. Fountas, Joseph R. Smith, Gregory P. Lee, Patrick D. Jenkins, Rebecca R. Cantrell and W. Chris Sheils
Stereotactic radiosurgery (SRS) with the Gamma Knife (GK) is a rapidly emerging surgical modality in the management of medically refractory idiopathic trigeminal neuralgia (TN). The current study examines the long-term outcome in patients with drug-resistant idiopathic TN who underwent GK surgery at the authors‘ institution.
One hundred and six consecutive patients (38 men and 68 women) with proven medically refractory idiopathic TN were included in this retrospective study. Their ages were 41–82 years (mean 72.3 years). All patients underwent SRS with prescribed maximal radiation doses ranging from 70 to 85 Gy. Isocenters 1–3 were used and plugging was used selectively. The follow-up period was 12–72 months (mean 34.3 months). The patients were divided into 2 groups according to their history of previous surgery.
The initial response rate in patients with no history of previous surgery was 92.9%; in those who had undergone previous surgery, the initial response rate was 85.7%. At the end of the 1st posttreatment year, an excellent outcome was achieved in 82.5% of patients who had not had previous surgery, and in 69.4% of those who had. The respective outcome rates for the 2nd posttreatment year were 78 and 63.5%, respectively. The most common complication was the development of persistent paresthesia, which occurred in 15.8% of patients with no previous surgery and 16.3% of those with previous surgery.
Stereotactic radiosurgery with the GK is a safe and effective treatment option for patients with medically refractory idiopathic TN.
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.
Kostas N. Fountas, Eftychia Kapsalaki and Georgios Hadjigeorgiou
The wide application of deep brain stimulation in the management of movement as well as other degenerative neurological and psychiatric disorders has renewed the interest in using deep brain stimulation in the management of medically intractable epilepsy. Various stimulation targets have been used with significantly varying results in aborting seizure activity. Electrical cerebellar stimulation (CS) has been used for more than 50 years in the management of epilepsy, with conflicting results. In the current study, the authors review the pertinent literature to outline the role of CS in the management of medically refractory epilepsy.
The PubMed medical database was systematically searched for the following terms: “cerebellar,” “epilepsy,” “stimulation,” and “treatment,” and all their combinations. Case reports were excluded from this study.
The pertinent articles were categorized into 2 large groups: animal experimental and human clinical studies. Particular emphasis on the following aspects was given when reviewing the human clinical studies: their methodological characteristics, the number of participants, their seizure types, the implantation technique and its associated complications, the exact stimulation target, the stimulation technique, the seizure outcome, and the patients' psychological and social poststimulation status. Three clinical double-blind studies were found, with similar implantation surgical technique, stimulation target, and stimulation parameters, but quite contradictory results. Two of these studies failed to demonstrate any significant seizure reduction, whereas the third one showed a significant poststimulation decrease in seizure frequency. All possible factors responsible for these differences in the findings are analyzed in the present study.
Cerebellar stimulation seems to remain a stimulation target worth exploring for defining its potential in the treatment of medically intractable epilepsy, although the data from the double-blind clinical studies that were performed failed to establish a clear benefit in regard to seizure frequency. A large-scale, double-blind clinical study is required for accurately defining the efficacy of CS in epilepsy treatment.