Automated measurement of anteroposterior diameter and foraminal widths in MRI images for lumbar spinal stenosis diagnosis.

Lumbar Spinal Stenosis causes low back pain through pressures exerted on the spinal nerves. This can be verified by measuring the anteroposterior diameter and foraminal widths of the patient's lumbar spine. Our goal is to develop a novel strategy for assessing the extent of Lumbar Spinal Stenosis by automatically calculating these distances from the patient's lumbar spine MRI. Our method starts with a semantic segmentation of T1- and T2-weighted composite axial MRI images using SegNet that partitions the image into six regions of interest. They consist of three main regions-of-interest, namely the Intervertebral Disc, Posterior Element, and Thecal Sac, and three auxiliary regions-of-interest that includes the Area between Anterior and Posterior elements. A novel contour evolution algorithm is then applied to improve the accuracy of the segmentation results along important region boundaries. Nine anatomical landmarks on the image are located by delineating the region boundaries found in the segmented image before the anteroposterior diameter and foraminal widths can be measured. The performance of the proposed algorithm was evaluated through a set of experiments on the Lumbar Spine MRI dataset containing MRI studies of 515 patients. These experiments compare the performance of our contour evolution algorithm with the Geodesic Active Contour and Chan-Vese methods over 22 different setups. We found that our method works best when our contour evolution algorithm is applied to improve the accuracy of both the label images used to train the SegNet model and the automatically segmented image. The average error of the calculated right and left foraminal distances relative to their expert-measured distances are 0.28 mm (p = 0.92) and 0.29 mm (p = 0.97), respectively. The average error of the calculated anteroposterior diameter relative to their expert-measured diameter is 0.90 mm (p = 0.92). The method also achieves 96.7% agreement with an expert opinion on determining the severity of the Intervertebral Disc herniations.

Long term neuropsychological outcome and management of 'decompensated' longstanding overt ventriculomegaly in adults.

OBJECTIVE: We aimed to study a group of patients presenting with symptomatic longstanding overt ventriculomegaly in adults (LOVA) requiring treatment (endoscopic third ventriculostomy), and to study their long term neuropsychological status and functionality. METHODS: Twenty patients were treated with endoscopic third ventriculostomy on presentation and were studied with neuropsychological assessments including the repeatable battery for the assessment of neuropsychological status and the hospital anxiety and depression scores. Pre- and post-operative MRI studies were used to assess the patency of the endoscopic third ventriculostomy (ETV) along with clinical outcome scores. RESULTS: A variety of presenting symptoms were experienced including headache (90%), worsening imbalance, attacks of loss of consciousness and cognitive decline. Mean age of patients was 52 years (range, 17-78) with mean head circumference of 60.9 cm. ETV was successful in controlling symptoms in 89% of patients with three patients requiring shunts (gravitational valves). There were no subdurals after surgery. All patients did universally badly in all aspects of the neuropsychological studies without showing any undue anxiety or depression. CONCLUSION: LOVA patients can decompensate at any time in their adult life with acute symptoms, which are generally well controlled with ETV and with few complications. Sadly, the long-term effects of carrying 'asymptomatic' or compensated hydrocephalus since childhood are of a significant cognitive cost to these patients.

A mechatronic valve in the management of hydrocephalus: methods and performance.

The problem of excess cerebrospinal fluid in the brain (hydrocephalus) is generally managed using a passive pressure or flow regulated mechanical shunt. Despite the success of such devices, they have been plagued with a number of problems. It is desirable to have a shunt valve that responds dynamically to the changing needs of the patient, opening and closing according to a dynamic physiological pattern, rather than simply to the hydrostatic pressure across the valve. Such a valve would by necessity be mechatronic, electronically controlled by software. In this article, different methods for controlling such a mechatronic valve are explored, and the effect of current hydrocephalus management techniques on the intracranial hydrodynamics of acute hydrocephalus patient compared with those based on a mechatronic valve was investigated using numerical simulation. Furthermore, the performance of these techniques was evaluated based on a proposed multi-dimensional figure of merit. In addition, an empirical valve schedule was proposed based on different criterions. An intelligent shunting system is seen as the future in hydrocephalus management and treatment, and towards this end, suitably programmed mechatronic valves would attempt to mimic normal physiology and potentially overcome many of the problems associated with current mechanical valves.

The role of endoscopic third ventriculostomy in adult patients with hydrocephalus.

OBJECT: Endoscopic third ventriculostomy (ETV) is the treatment of choice for hydrocephalus, but the outcome is dependent on the cause of this disorder, and the procedure remains principally the preserve of pediatric neurosurgeons. The role of ETV in adult patients with hydrocephalus was therefore investigated. METHODS: One hundred ninety adult patients underwent ETV for hydrocephalus. Cases were defined as primary ETV (newly diagnosed, without a previously placed shunt) and secondary ETV (performed for shunt malfunctions due to infection or mechanical blockage). Causes of hydrocephalus included tumor, long-standing overt ventriculomegaly (LOVA), Chiari malformation Types I and II (CM-I and -II), aqueduct stenosis, spina bifida, and intraventricular hemorrhage (IVH). Successful ETV was defined as resolution of symptoms with shunt independence. Operative complications and ETV failure rate were investigated according to the causes of hydrocephalus and between the primary and secondary ETV groups. RESULTS: In the primary group, ETV was successful in 107 (83%) of 129 patients, including those with tumors (52 of 66), LOVA (21 of 24), CM-I (11 of 11 cases), CM-II (8 of 9), aqueduct stenosis (8 of 9), and IVH (2 of 2). In the secondary group, ETV was successful in 41 (67%) of 61 patients and was equally successful in cases of mechanical shunt malfunction (35 of 52 patients) and infected shunt malfunction (6 of 9 patients). The median time to ETV failure was 1.7 months in the primary group and 0.5 months in the secondary group. The majority of ETV failures occurred within the first 3 months, and thereafter, the Kaplan-Meier survival curves plateaued. There were no procedure-related deaths, and complications were seen in only 5.8% of cases. CONCLUSIONS: The success rate of ETVs in adults is comparable, if not better, than in children. In addition to the well-defined role of ETV in the treatment of hydrocephalus caused by tumors and aqueduct stenosis, ETV may also have a role in the management of CM-I, LOVA, persistent shunt infection, and IVH resistant to other CSF diversion procedures.

Expression of three distinct families of calcium-activated chloride channel genes in the mouse dorsal root ganglion.

Objective A calcium-activated chloride current (IClCa) has been observed in medium-sized sensory neurons of the dorsal root ganglion (DRG). Axotomy of the sciatic nerve induces a similar current in the majority of medium and large diameter neurons. Our aim is to identify the molecule(s) underlying this current. Methods Using conventional and quantitative RT-PCR, we examined the expression in DRG of members of three families of genes, which have been shown to have IClCa current inducing properties. Results We showed the detection of transcripts representing several members of these families, i.e. chloride channel calcium-activated (CLCA), Bestrophin and Tweety gene families in adult DRG, in the normal state and 3 d after sciatic nerve section, a model for peripheral nerve injury. Conclusion Our analysis revealed that that mBest1 and Tweety2 appear as the best candidates to play a role in the injury-induced IClCa in DRG neurons.

Gene profiling during development and after a peripheral nerve traumatism reveals genes specifically induced by injury in dorsal root ganglia.

In order to shed light on transcriptional networks involved in adult peripheral nerve repair program, we propose for the first time an organization of the transcriptional dynamics of the mouse dorsal root ganglia (DRG) following a sciatic nerve lesion. This was done by a non-hierarchical bioinformatical clustering of four Serial Analysis of Gene Expression libraries performed on DRG at embryonic day E13, neonatal day P0, adult and adult 3 days post-sciatic nerve section. Grouping genes according to their expression profiles shows that a combination of down-regulation of genes expressed at the adult stages, re-expression of embryonic genes and induction of a set of de novo genes takes place in injured neurons. Focusing on this latter event highlights Ddit3, Timm8b and Oazin as potential new injury-induced molecular actors involved in a stress response pathway. Their association with the traumatic state was confirmed by real-time PCR and in situ hybridization investigations. Clustering analysis allows us to distinguish developmental re-programming events from nerve-injury-induced processes and thus provides a basis for molecular understanding of transcriptional alterations taking place in the DRG after a sciatic nerve lesion.

Calcium dependence of axotomized sensory neurons excitability.

Hyperexcitability of axotomized dorsal root ganglion neurons is thought to play a role in neuropathic pain. Numerous changes in ionic channels expression or current amplitude are reported after an axotomy, but to date no direct correlation between excitability of axotomized sensory neurons and ionic channels alteration has been provided. Following sciatic nerve injury, we examined, under whole-cell patch clamp recording, the effects of calcium homeostasis on the electrical activity of axotomized medium-sized sensory neurons isolated from lumbar dorsal root ganglia of adult mice. Axotomy induced an increase in excitability of medium sensory neurons among which 25% develop a propensity to fire repetitively. The condition necessary to get burst discharge in axotomized neurons was the presence of a high intracellular Ca2+ buffer concentration. The main effect was to amplify the increase in threshold current and apparent input resistance induced by axotomy. These data supply evidence for a role of Ca2+-dependent mechanisms in the control of excitability of axotomized sensory neurons.

Axotomy-induced expression of calcium-activated chloride current in subpopulations of mouse dorsal root ganglion neurons.

Whole cell patch-clamp recordings of calcium-activated chloride current [ICl(Ca)] were made from adult sensory neurons of naive and axotomized mouse L4-L6 lumbar dorsal root ganglia after 1 day of culture in vitro. A basal ICl(Ca) was specifically expressed in a subset of naive medium-diameter neurons (30-40 microm). Prior nerve injury, induced by sciatic nerve transection 5 days before experiments, increased both ICl(Ca) amplitude and its expression in medium-diameter neurons. Moreover, nerve injury also induced ICl(Ca) expression in a new subpopulation of neurons, the large-diameter neurons (40-50 microm). Small-diameter neurons (inferior to 30 microm) never expressed ICl(Ca). Regulated ICl(Ca) expression was strongly correlated with injury-induced regenerative growth of sensory neurons in vitro and nerve regeneration in vivo. Cell culture on a substrate not permissive for growth, D,L-polyornithine, prevented both elongation growth and ICl(Ca) expression in axotomized neurons. Regenerative growth and the induction of ICl(Ca) expression take place 2 days after injury, peak after 5 days of conditioning in vivo, slowly declining thereafter to control values. The selective expression of ICl(Ca) within medium- and large-diameter neurons conditioned for rapid, efficient growth suggests that these channels play a specific role in postinjury behavior of sensory neuron subpopulations such as neuropathic pain and/or axonal regeneration.