Feridun Acar

Radiographic evaluation of trigeminal neurovascular compression in patients with and without trigeminal neuralgia.

OBJECT Neurovascular compression (NVC) of the trigeminal nerve is associated with trigeminal neuralgia (TN), but also occurs in many patients without facial pain. This study is designed to identify anatomical characteristics of NVC associated with TN. METHODS Thirty patients with Type 1 TN (intermittent shocklike pain) and 15 patients without facial pain underwent imaging for analysis of 30 trigeminal nerves ipsilateral to TN symptoms, 30 contralateral to TN symptoms, and 30 in asymptomatic patients. Patients underwent 3-T MR imaging including balanced fast-field echo and MR angiography. Images were fused and reconstructed into virtual cisternoscopy images that were evaluated to determine the presence and degree of NVC. Reconstructed coronal images were used to measure nerve diameter and crosssectional area. RESULTS The incidence of arterial NVC in asymptomatic nerves, nerves contralateral to TN symptoms, and nerves ipsilateral to TN symptoms was 17%, 43%, and 57%, respectively. The difference between symptomatic and asymptomatic nerves was significant regarding the presence of NVC, nerve distortion, and the site of compression (p < 0.001, Fisher exact test). The most significant predictors of TN were compression of the proximal nerve (odds ratio 10.4) and nerve indentation or displacement (odds ratio 4.3). There was a tendency for the development of increasingly severe nerve compression with more advanced patient age across all groups. Decreased nerve size was observed in patients with TN but did not correlate with the presence or extent of NVC. CONCLUSIONS Trigeminal NVC occurs in asymptomatic patients but is more severe and more proximal in patients with TN. This information may help identify patients who are likely to benefit from microvascular decompression.

Classification of trigeminal neuralgia: clinical, therapeutic, and prognostic implications in a series of 144 patients undergoing microvascular decompression

OBJECT Trigeminal neuralgia (TN) presents a diagnostic challenge because of the variety of symptoms, findings during microvascular decompression (MVD), and postsurgical outcomes observed among patients who suffer from this disorder. Recently, a new paradigm for classification of TN was proposed, based on the quality of pain. This study represents the first clinical analysis of this paradigm. METHODS The authors analyzed 144 consecutive cases involving patients who underwent MVD for TN. Preoperative symptoms were classified into 1 of 2 categories based on the preponderance of shocklike (Type 1 TN) or constant (Type 2 TN) pain. Analysis of clinical characteristics, neurovascular pathology, and postoperative outcome was performed. RESULTS Compared with Type 2 TN, Type 1 TN patients were older, were more likely to have right-sided symptoms, and reported a shorter duration of symptoms prior to evaluation. Previous treatment by percutaneous or radiosurgical procedures was not a predictor of symptoms, surgical findings, or outcome (p = 0.48). Type 1 TN was significantly more likely to be associated with arterial compression. Venous or no compression was more common among Type 2 TN patients (p < 0.01). Type 1 TN patients were also more likely to be pain-free immediately after surgery, and less likely to have a recurrence of pain within 2 years (p < 0.05). Although a subset of patients progressed from Type 1 to Type 2 TN over time, their pathological and prognostic profiles nevertheless resembled those of Type 1 TN. CONCLUSIONS Type 1 and Type 2 TN represent distinct clinical, pathological, and prognostic entities. Classification of patients according to this paradigm should be helpful to determine how best to treat patients with this disorder.

Preoperative visualization of neurovascular anatomy in trigeminal neuralgia

OBJECT The authors report on a novel technique to identify neurovascular compression in trigeminal neuralgia (TN). Using 3D reconstructed high-resolution balanced fast-field echo (BFFE) images fused with 3D time-of-flight (TOF) magnetic resonance (MR) angiography and Gd-enhanced 3D spoiled gradient recalled sequence, it is possible to objectively visualize the trigeminal nerve and nearby arteries and veins. METHODS Magnetic resonance imaging was performed in 18 patients with unilateral TN using 3 sequences: BFFE, 3D TOF angiography, and 3D Gd-enhanced imaging. The images were imported into OsiriX imaging software; after their fusion, a 3D false-color reconstruction was produced using surface rendering. The reconstructed images objectively differentiate nerves and vessels and can be viewed from any angle, including the anticipated surgical approach. RESULTS Fifteen patients were predicted to have neurovascular compression on the symptomatic side (9 arterial and 6 venous compressions). All patients had a vascular structure that was identical in location and configuration to that predicted on preoperative analysis. The 3 patients without predicted compression underwent surgical exploration because they manifested the classic symptoms. As expected, exploration in 2 of these patients revealed no offending vessel. The third patient had a small vein embedded in the trigeminal nerve that was beyond the resolution of the 3D Gd-enhanced study. CONCLUSIONS Combining BFFE with MR angiography and Gd-enhanced MR images capitalizes on the advantages of both techniques, enabling MR angiography and contrast-enhanced MR imaging discrimination of vascular structures at BFFE resolution. This results in an unambiguous 3D image that can be used to identify the neurovascular compression and plan the surgical approach.

Significant reduction in stereotactic and functional neurosurgical hardware infection after local neomycin/polymyxin application.

OBJECT Hardware infection is a common occurrence after the implantation of neurostimulation and intrathecal drug delivery devices. The authors investigated whether the application of a neomycin/polymyxin solution directly into the surgical wound decreases the incidence of perioperative infection. METHODS Data from all stereotactic and functional hardware procedures performed at the Oregon Health & Science University over a 5-year period were reviewed. All patients received systemic antibiotic prophylaxis. For the last 18 months of the 5-year period, wounds were additionally injected with a solution consisting of 40 mg neomycin and 200,000 U polymyxin B sulfate diluted in 10 ml normal saline. The primary outcome measure was infection of the hardware requiring explantation. RESULTS Six hundred fourteen patients underwent hardware implantation. Among 455 patients receiving only intravenous antibiotics, the infection rate was 5.7%. Only 2 (1.2%) of 159 patients receiving both intravenous and local antibiotics had an infection. The wounds in both of these patients were compromised postoperatively: 1 patient had entered a swimming pool, and the other had undergone a general surgery procedure that exposed the hardware. If these patients are excluded from analysis, the effective infection rate using a combined intravenous and local antibiotic prophylaxis is 0%. There were no complications due to toxicity. CONCLUSIONS The combination of local neomycin/polymyxin with systemic antibiotic therapy can lead to a significantly lower rate of postoperative infection than when systemic antibiotics are used alone.

Functional Anatomy of the Spine by Avicenna in His Eleventh Century Treatise Al-Qanun fi al-Tibb (The Canons of Medicine)

The history of spinal surgery is an important part of the spine-related sciences. The development of treatment strategies for spine-related disorders is acquired from the Western literature. In this article, an Eastern physician, Ibn Sina, who is known as Avicenna in the West, and his treatise, Al-Qanun fi al-Tibb (the Canons of Medicine), are presented. Eight chapters of this book regarding the functional neuroanatomy of the spine were reviewed and are presented to give insight into the development of the understanding of spinal anatomy and biomechanics.

Safety of anterior commissure-posterior commissure-based target calculation of the subthalamic nucleus in functional stereotactic procedures

The subthalamic nucleus (STN) is a common target of functional stereotactic surgeries. High-field magnetic resonance imaging and sophisticated computer systems provide precise identification of the nucleus location in stereotactic space. However, it is unclear what additional benefit these techniques provide over traditional anterior commissure-posterior commissure (AC-PC)-based standard atlas coordinate calculation methods based on the AC-PC plane. The accuracy of AC-PC-based standard atlas coordinate targeting of the STN using 1.5-tesla images compared with direct visualization of the nucleus on fused 3-tesla images was examined. A retrospective examination of stereotactic images from 20 patients (40 STN targets) who underwent deep brain stimulation for Parkinson’s disease was undertaken at our institution. Two methods were used to identify the STN stereotactic coordinates: (1) an AC-PC-based standard atlas coordinate calculation obtained by a series of measurements using 1.5-tesla images, and (2) a computer workstation calculation using fused 3-tesla and 1.5-tesla images. Euclidean distances between two sets of coordinates of the same target were calculated in three dimensions. Differences along individual X, Y, and Z axes were analyzed to determine whether there was a greater difference in one direction than in another. Data from the right and left sides were pooled to increase the sample power. The anterior-posterior and lateral frame tilts were compared to X, Y, and Z differences to find a correlation using linear regression. Statistical analyses were performed. The accuracy of the position of the STN calculated with state-of-the-art imaging systems was not significantly better than that obtained using traditional AC-PC-based standard atlas coordinate calculation if the frame was aligned with the AC-PC plane. The mean difference was 0.45 mm, 0.72 mm, and 0.98 mm in the X, Y, and Z axes, respectively. Therefore, it is possible to effectively target the STN for stereotactic treatment of Parkinson’s disease, for instance in a situation where expensive advanced technology is unavailable.

Pain relief after cervical ganglionectomy (C2 and C3) for the treatment of medically intractable occipital neuralgia.

Occipital neuralgia (ON) presents a diagnostic challenge because of the wide variety of symptoms, surgical findings, and postsurgical outcomes. Surgical removal of the second (C2) or third (C3) cervical sensory dorsal root ganglion is an option to treat ON. The goal of this study was to evaluate the short-term and the long-term efficacy of these procedures for management of cervical and occipital neuropathic pain. Twenty patients (mean age 48.7 years) were identified who had undergone C2 and/or C3 ganglionectomies for intractable occipital pain and a retrospective chart review undertaken. Patients were interviewed regarding pain relief, pain relief duration, functional status, medication usage and procedure satisfaction, preoperatively, immediately postoperative, and at follow-up (mean 42.5 months). C2, C3 and consecutive ganglionectomies at both levels were performed on 4, 5, and 11 patients, respectively. All patients reported preoperative pain relief following cervical nerve blocks. Average visual analog scale scores were 9.4 preoperatively and 2.6 immediately after procedure. Ninety-five percent of patients reported short-term pain relief (<3 months). In 13 patients (65%), pain returned after an average of 12 months (C2 ganglionectomy) and 8.4 months (C3 ganglionectomy). Long-term results were excellent, moderate and poor in 20, 40 and 40% of patients, respectively. Cervical ganglionectomy offers relief to a majority of patients, immediately after procedure, but the effect is short lived. Nerve blocks are helpful in predicting short-term success, but a positive block result does not necessarily predict long-term benefit and therefore cannot justify surgery by itself. However, since 60% of patients report excellent-moderate results, cervical ganglionectomy continues to have a role in the treatment of intractable ON.

Anatomical and computed tomographic analysis of C1 vertebra

Craniovertebral junction surgery requires knowledge regarding the anatomy of this region, particularly the C1 vertebra. Both C1 laminectomy and C1-2 instrumentation necessitate preoperative information about bony landmarks and the vertebral artery. This study compares the results obtained from anatomic and computed tomographic measurements of C1 bony landmarks. 31 C1 cervical vertebrae were measured; the C1 AP diameter, and C1 transverse diameter, the facet diameter, the distance between the anterior tubercle and the anterior aspect of the C1 lateral mass on a lateral view, the distance between the midline and the vertebral artery groove on the outer cortex of the posterior arch of C1 anatomically and computed tomographically. Anatomic measurements were performed by an anatomist using a Vernier caliper accurate to 0.1 mm, whereas the computed tomographic measurements were performed by a radiologist on bone window computed tomography (CT). The mean values and the differences between two measurement modalities were analysed using a paired t-test. There was no statistical difference between the results obtained by anatomical and radiological measurements for six parameters. There was, however, a statistically significant difference between two modalities regarding the distance between the midline and vertebral artery groove on the outer cortex of posterior arch of C1, while slightly different, the difference is within 1 mm and, therefore, not clinically significant. It is concluded that CT reflects most anatomical details of bony landmarks of C1.

Pathology of ilioinguinal neuropathy produced by mesh entrapment: case report and literature review

Ilioinguinal neuropathy is a well-described complication of mesh inguinal herniorrhaphy. We report the first human case, to our knowledge, of ilioinguinal nerve mesh entrapment with neuropathological changes that suggest an inflammatory cause for this chronic pain syndrome.

Seizure Outcome following Transcortical Selective Amygdalohippocampectomy in Mesial Temporal Lobe Epilepsy

The aim of this study was to retrospectively determine if patients with medically refractory epilepsy, due to hippocampal sclerosis, who underwent selective amygdalohippocampectomy (SAH) with a transcortical approach experienced improved seizure outcome. Thirty-nine patients with mesial temporal lobe epilepsy and hippocampal sclerosis were included in the study. The mean follow-up was 25.88 ± 17.69 months. Antiepileptic medication use and seizure frequency were significantly reduced after SAH. After surgery, 32 patients (82.05%) were completely seizure free (Engel class IA), and 2 patients experienced transient memory difficulty. In conclusion, SAH with a transcortical approach can lead to favorable seizure control with a low irreversible complication risk.