Seizures as presentation of shunt malfunction: tertiary paediatric neurosurgery experience.

AIM: Patients with a background of cerebrospinal fluid (CSF)-diverting shunts are frequently investigated for shunt malfunction when presenting with seizures. However, there is very limited evidence in the literature regarding the association of seizures and shunt malfunction. We sought to determine the incidence of shunt malfunction in our cohort of shunted paediatric patients presenting with seizures, and the utility of seizures as a marker of shunt malfunction. METHODS: We retrospectively identified all shunted patients presenting with seizures, as well as all patients undergoing shunt revision following a presentation with seizures from our hospital database over a 14-year period from 2009 to 2023. Data gathered included demographics, de novo seizures or change in pattern of seizures, the aetiology of hydrocephalus and the segment of shunt requiring revision. Exclusion criteria included infected cases requiring shunt externalisation. A literature review of all papers discussing seizures as a presentation of shunt malfunction was also carried out. RESULTS: Overall, over a 14-year period of study, 338 shunted patients presented with seizures and were referred as suspected shunt malfunction with 10 having confirmed shunt malfunction requiring revision (2.9%). This group represented 6.2% of 161 cases of shunt revision carried out during the 14-year period of study. Post-haemorrhagic hydrocephalus secondary to prematurity was the commonest aetiology of shunted hydrocephalus presenting with seizures. Out of 10 patients presenting with seizures with shunt malfunction, 4 presented with de novo seizures, while 6 presented with a change in seizure pattern or frequency in already known epileptic patients. Shunt revision surgeries included 5 distal catheter, 2 proximal catheter, 1 proximal catheter-valve, 1 valve only and 1 case of whole shunt change. CONCLUSION: Our data supports that seizures are rare manifestation of shunt malfunction and can present either de novo or with a change in seizure frequency in already-known epileptic patients.

Factors affecting endoscopic third ventriculostomy success in adults.

BACKGROUND: Endoscopic third ventriculostomy (ETV) is a standard treatment in hydrocephalus of certain aetiologies. The most widely used predictive model is the ETV success score. This is frequently used to predict outcomes following ETV in adult patients; however, this was a model developed in paediatric patients with often distinct aetiologies of hydrocephalus. The aim of this study was to assess the predictive value of the model and to identify factors that influence ETV outcomes in adults. METHODS: A retrospective study design was used to analyse consecutive patients who underwent ETV at a tertiary neurosurgical centre between 2012 and 2020. Observed ETV outcomes at 6 months were compared to pre-operative predicted ETV success scores. A multivariable Bayesian logistic regression analysis was used to determine the factors that best predicted ETV success and those factors that were redundant. RESULTS: A total of 136 patients were analysed during the 9-year study. Thirty-one patients underwent further cerebrospinal fluid diversion within 6 months. The overall ETV success rate was 77%. Observed ETV outcomes corresponded well with predicted outcomes using the ETV success score for the higher scores, but less well for lower scores. Location of obstruction at the aqueduct irrespective of aetiology was the best predictor of success with odds of 1.65 of success. Elective procedures were also associated with higher success compared to urgent ones, whereas age under 70, nature and location of obstructive lesion (other than aqueductal) did not influence ETV success. CONCLUSION: ETV was successful in three-quarters of adult patient with hydrocephalus within 6 months. Obstruction at the level of the aqueduct of any aetiology was a good predictor of ETV success. Clinicians should bear in mind that adult hydrocephalus responds differently to ETV compared to paediatric hydrocephalus, and more research is required to develop and validate an adult-specific predictive tool.

The zebrafish mutant dreammist implicates sodium homeostasis in sleep regulation.

Sleep is a nearly universal feature of animal behaviour, yet many of the molecular, genetic, and neuronal substrates that orchestrate sleep/wake transitions lie undiscovered. Employing a viral insertion sleep screen in larval zebrafish, we identified a novel gene, dreammist (dmist), whose loss results in behavioural hyperactivity and reduced sleep at night. The neuronally expressed dmist gene is conserved across vertebrates and encodes a small single-pass transmembrane protein that is structurally similar to the Na+,K+-ATPase regulator, FXYD1/Phospholemman. Disruption of either fxyd1 or atp1a3a, a Na+,K+-ATPase alpha-3 subunit associated with several heritable movement disorders in humans, led to decreased night-time sleep. Since atpa1a3a and dmist mutants have elevated intracellular Na+ levels and non-additive effects on sleep amount at night, we propose that Dmist-dependent enhancement of Na+ pump function modulates neuronal excitability to maintain normal sleep behaviour.

Volume maximised glycerol rhizolysis for trigeminal neuralgia: a single centre analysis of outcomes.

OBJECTIVES: Glycerol rhizotomy is an established treatment for medically refractory trigeminal neuralgia in select cases where microvascular decompression is contraindicated or not preferred. The standard approach is to inject a fixed volume of glycerol using Hartel's technique into Meckel's cave. We discuss a 'volume-maximised' technique of measuring the volume of Meckel's cave using intra-operative fluoroscopy and injecting an equivalent volume of glycerol such that every patient receives a tailored quantity of glycerol dependent on the volume of Meckel's cave. The safety and efficacy of this approach is analysed. METHODS: A retrospective analysis of 53 procedures where volume-maximised glycerol rhizolysis was utilised over a 7-year period (2012 -2018) at a single centre by the senior author was carried out. The incidence and duration of pain freedom and complications incurred over a median follow-up period of 8 years were analysed. RESULTS: 37 procedures were carried out for typical trigeminal neuralgia, 13 for secondary trigeminal neuralgia, and 3 for atypical trigeminal neuralgia. Overall, pain freedom was achieved in 85% cases, and 92% in patients with typical trigeminal neuralgia. Median duration of pain freedom in patients with typical trigeminal neuralgia was 63 months, versus 6 months in those with secondary trigeminal neuralgia (p < 0.00001). 14 procedures (26.4%) resulted in mild and temporary complications. 54.7% of cases experienced hypoaesthesia in a distribution similar to or less extensive than the distribution of trigeminal neuralgia. The presence of hypoaesthesia post-procedure was highly predictive of longer pain freedom (95 months versus 8 months median pain freedom (p = 0.00003)). CONCLUSIONS: Volume-maximised glycerol injection is safe and effective when compared to literature-reported outcomes post-standard volume glycerol injections. The duration of pain freedom achieved exceeds most literature-reported studies, with hypoaesthesia outcomes being comparable with previous studies. Pain freedom outcomes are more favourable in those with post-procedure hypoaesthesia.

Regional Scalp Blockade for Painless Removal ofIntracranial Pressure Bolts: Technical Note and Patient-Reported Outcomes.

OBJECTIVE: Elective insertion of intracranial pressure (ICP) monitoring bolts is useful for the diagnosis and treatment of disorders of cerebrospinal fluid dynamics. Patients typically report severe discomfort on bolt removal, which negatively impacts overall patient satisfaction of ICP monitoring. We assessed the efficacy and safety of using supratrochlear and supraorbital nerve block-a commonly used form of scalp anesthesia-alongside oral analgesia before bolt removal. METHODS: We compared the efficacy and safety of regional scalp block anesthesia alongside oral analgesia versus oral analgesia alone in a cohort of 85 patients undergoing removal of diagnostic ICP bolts between June 2017 and April 2019 using retrospective patient questionnaires, as well as electronic admission documentation. RESULTS: We found that scalp block alongside oral analgesia improved bolt removal experience (4/5 vs. 3/5 on a 1-5 point Likert scale) and that a majority (70.6%) of patients would have preferred local anesthetic before removal in the oral analgesia-only group. Only 2 patients experienced mild and localized side effects: mild bruising and temporary facial and eyelid swelling following regional scalp block. CONCLUSIONS: We conclude that regional supraorbital and supratrochlear nerve block is a simple, safe, and effective adjunct to minimizing discomfort during bolt removal and improving overall patient satisfaction of ICP monitoring.

Acute-onset polyradiculoneuropathy after SARS-CoV2 vaccine in the West and North Midlands, United Kingdom.

INTRODUCTION/AIMS: We aimed to determine whether specific severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) vaccines may be associated with acute-onset polyradiculoneuropathy and if they may result in particular clinical presentations. METHODS: We retrospectively reviewed records of all persons presenting with acute-onset polyradiculoneuropathy from January 1, 2021, to June 30, 2021, admitted to two Neuroscience centers, of the West and North Midlands, United Kingdom. We compared subjects with previous SARS-CoV2 vaccine exposure with a local cohort of persons with acute-onset polyradiculoneuropathy admitted between 2005 and 2019 and compared admission numbers for the studied time frame with that of the previous 3 years. RESULTS: Of 24 persons with acute-onset polyradiculoneuropathy, 16 (66.7%) presented within 4 weeks after first SARS-CoV2 vaccine. Fourteen had received the AstraZeneca vaccine and one each, the Pfizer and Moderna vaccines. The final diagnosis was Guillain-Barré syndrome (GBS) in 12 and acute-onset chronic inflammatory demyelinating polyneuropathy in 4. Among AstraZeneca vaccine recipients, facial weakness in nine persons (64.3%), bulbar weakness in seven (50%), and the bifacial weakness and distal paresthesias GBS variant in three (21.4%), were more common than in historical controls (P = .01; P = .004, and P = .002, respectively). A 2.6-fold (95% confidence interval: 1.98-3.51) increase in admissions for acute-onset polyradiculoneuropathy was noted during the studied time frame, compared to the same period in the previous 3 years. DISCUSSION: Despite a low risk, smaller than that of SARS-CoV2 infection and its complications, exposure to the first dose of AstraZeneca SARS-CoV2 vaccine may be a risk factor for acute-onset polyradiculoneuropathy, characterized by more common cranial nerve involvement.

White Fiber Correlates of Amygdalohippocampectomy Through the Middle Temporal Gyrus Approach.

OBJECTIVE: The white fiber and gross anatomy relevant for performing amygdalohippocampectomy through the middle temporal gyrus approach for mesial temporal sclerosis has been depicted by white fiber dissection. METHODS: Three previously frozen and formalin fixed cerebral hemispheres were studied. The Klingler method of fiber dissection was used to study the anatomy. The primary tools used were hand-made wooden spatulas, forceps, and microscissors. The anatomy of the amygdala and hippocampus and the landmarks for performing the disconnection during epilepsy surgery are presented. The white fibers at risk during the middle temporal gyrus approach were studied. RESULTS: The white fiber tracts at risk during the middle temporal gyrus approach for epilepsy surgery are the fibers of the inferior frontooccipital fasciculus, temporal extension of the anterior commissure, Meyer loop of the optic radiation, and uncinate fasciculus. On the basis of our anatomic dissections, we present a novel entry point into the temporal horn, potentially minimizing injury to the fibers of the sagittal stratum. We also propose novel landmarks to perform the amygdala disconnection in mesial temporal sclerosis. CONCLUSIONS: The middle temporal gyrus is a commonly used approach to perform temporal lobectomy and amygdalohippocampectomy for patients with mesial temporal sclerosis. The anatomy relevant to the approach as presented will aid while performing epilepsy surgery.

Neurosurgery activity levels in the United Kingdom and republic of Ireland during the first wave of the covid-19 pandemic - a retrospective cross-sectional cohort study.

The impact of Covid-19 on surgical patients worldwide has been substantial. In the United Kingdom (UK) and the Republic of Ireland (RoI), the first wave of the pandemic occurred in March 2020. The aims of this study were to: (1) evaluate the volume of neurosurgical operative activity levels, Covid-19 infection rate and mortality rate in April 2020 with a retrospective cross-sectional cohort study conducted across 16 UK and RoI neurosurgical centres, and (2) compare patient outcomes in a single institution in April-June 2020 with a comparative cohort in 2019. Across the UK and RoI, 818 patients were included. There were 594 emergency and 224 elective operations. The incidence rate of Covid-19 infection was 2.6% (21/818). The overall mortality rate in patients with a Covid-19 infection was 28.6% (6/21). In the single centre cohort analysis, an overall reduction in neurosurgical operative activity by 65% was observed between 2020 (n = 304) and 2019 (n = 868). The current and future impact on UK neurosurgical operative activity has implications for service delivery and neurosurgical training.

Dynamic causal modelling of immune heterogeneity.

An interesting inference drawn by some COVID-19 epidemiological models is that there exists a proportion of the population who are not susceptible to infection-even at the start of the current pandemic. This paper introduces a model of the immune response to a virus. This is based upon the same sort of mean-field dynamics as used in epidemiology. However, in place of the location, clinical status, and other attributes of people in an epidemiological model, we consider the state of a virus, B and T-lymphocytes, and the antibodies they generate. Our aim is to formalise some key hypotheses as to the mechanism of resistance. We present a series of simple simulations illustrating changes to the dynamics of the immune response under these hypotheses. These include attenuated viral cell entry, pre-existing cross-reactive humoral (antibody-mediated) immunity, and enhanced T-cell dependent immunity. Finally, we illustrate the potential application of this sort of model by illustrating variational inversion (using simulated data) of this model to illustrate its use in testing hypotheses. In principle, this furnishes a fast and efficient immunological assay-based on sequential serology-that provides a (1) quantitative measure of latent immunological responses and (2) a Bayes optimal classification of the different kinds of immunological response (c.f., glucose tolerance tests used to test for insulin resistance). This may be especially useful in assessing SARS-CoV-2 vaccines.

Corpus Callosum and Its Connections: A Fiber Dissection Study.

OBJECTIVE: We performed a fine white fiber dissection to demonstrate the extensive connections of the corpus callosum. MATERIAL AND METHODS: Three formalin-fixed frozen cadaveric human brain specimens were dissected using Klingler's technique. On one half of each hemisphere, the superior connections of the corpus callosum were dissected and in the other half the inferior connections of the corpus callosum were dissected. RESULTS: The mean length of the corpus callosum from the rostrum to the splenium was 7.8 cm. The fibers of the corpus callosum were classified as superior/dorsal radiations, inferior/ventral radiations, anterior radiations, and posterior radiations. The entire transverse length of the dorsal callosal radiation from one hemisphere to the other was 8.1 cm. For anterior interhemispheric approaches, an incision in the anterior part of the body not extending beyond 3.5 cm from the genu was found to be safe with regards to crossing motor fibers. CONCLUSIONS: The corpus callosum was found to have intricate connections with all the lobes of the cerebral hemispheres, including the insular region and the limbic and paralimbic areas. Based on the course and traverse of the callosal fibers, a transverse incision in the corpus callosum should be preferred when performing a callosotomy to access intraventricular lesions as this splits the callosal fibers instead of transecting them. The analysis of the course of the callosal radiations enhances understanding of the growth pattern of primary corpus callosal gliomas and helps to design a safe surgical strategy.

A morphological analysis of the cervical spine of the dolphin.

OBJECTIVE: Morphology of bones of cervical vertebrae of dolphin was studied. When compared to human vertebrae the structural modifications in terms of functional needs are evaluated. MATERIAL: Morphological analysis of duly prepared bones of species D. delphis was carried out. RESULT: The craniocervical junction and cervical spine of the dolphin (Delphinus delphis) has unique adaptations to allow for dorsoventrally undulating swimming movements as well as leaping out of water. The key differences from the human cervical spine include the absence of an odontoid process limiting rotatory movements, disproportionately short and wide vertebral bodies and a unilaterally elongated transverse process of the axis. Moreover, the cervical spine of the dolphin is disproportionally short compared to humans. These modifications give strength and stability to the cervical spine allowing maximal agility for flexion-extension movements of the lumbocaudal spine, which are keys for propulsion. The unilaterally elongated transverse process likely allows for rotatory spinning, suggesting possible lateral dominance of rotatory spin in this species. CONCLUSIONS: Despite the skeletal adaptations, the cervical spine is strongly resonant of a mammalian heritage with a remarkably similar form and structure to house neurovascular contents and to allow muscular attachments.

External syringomyelia in longstanding benign foramen magnum tumors.

BACKGROUND: The effect of benign foramen magnum tumours on cranial and spinal dimensions and cerebrospinal fluid (CSF) spaces is unclear. In this study, we measured alterations in cerebrospinal fluid (CSF) spaces in the spinal canal and in the posterior cranial fossa distant from the site of benign foramen magnum tumors. METHODS: Twenty-nine magnetic resonance imaging scans of patients with foramen magnum tumors (8 meningiomas and 21 C2 neurinomas) were identified for radiological morphometric analysis and compared with normal control scans. The anterior-posterior distance between the pontomedullary junction and the clivus, the spinal canal diameter, spinal cord diameter, and cord-canal ratios were measured at the C6 and T2 levels. RESULTS: The mean spinal canal diameter was significantly higher in tumor scans at both the C6 and T2 spinal levels than in controls (13.8 mm vs. 11.4 mm at C6; p<0.0001, and 12.9 mm vs. 11.9 mm at T2; P=0.01). Further, the mean cord:canal ratio was significantly lower in tumor scans at both levels (0.49 vs. 0.64 at C6; P<0.0001, and 0.45 vs. 0.54 at T2; P=0.0009). There was no significant difference in mean anteroposterior distance from the clivus to the pontomedullary junction (10.4 mm vs. 10.3 mm; P=0.91). CONCLUSION: In the presence of benign foramen magnum tumors, the spinal canal diameter and CSF volume in the spinal canal increased at the C6 and T2 levels, distant from the tumor site, a phenomenon we describe as "external syringomyelia".

Brainstem Anatomy: A Study on the Basis of the Pattern of Fiber Organization.

OBJECTIVE: A focused dissection of the brainstem was performed to study the various fiber bundles and gray matter nuclei of the brainstem and to decipher the intricate anatomy. METHODS: Ten formalin-fixed cadaveric human brains were procured. The fiber dissection techniques described by Klingler were then adopted to study the anatomy. The primary dissection tools used were thin handmade wooden spatulas and fine jeweler's forceps. The fibers were dissected layer by layer with the use of magnification. RESULTS: The brainstem dissection was performed from the dorsal, ventral, and lateral aspects to provide a 3-dimensional perspective of the internal architecture. We have presented a novel classification of the brainstem white matter in accordance with the internal organization. The fiber tracts of the brainstem can be divided into short projection fibers, long projection fibers, traversing fibers, and association fibers. From our dissection findings, we divided these white fibers of the brainstem into 3 zones from laterally to medially. The first or outermost zone consists of short projection fibers connecting the brainstem to the cerebellum and adjacent thalamic nuclei. The second zone or the middle zone lies medial to the first zone and consists of traversing and long projection fibers. These consist of both ascending and descending fibers. The third zone or the innermost zone consists of the brainstem association fibers. CONCLUSIONS: This division of the fiber bundles into zones will help neurosurgeons in understanding the course and anatomy of the fibers, which can be cumbersome to remember when only studying the sectional anatomy of the brainstem.

Approach to Slitlike Ventricles: Parietal-Occipital versus Frontal Burr Catheter Entry Sites.

BACKGROUND: Slit ventricles can be a challenging target during shunt catheter insertion. Traditionally, the frontal approach has been considered optimal for small ventricles. At this center, routine use of electromagnetic (EM) stereotactic guidance (Stealth, Medtronic, Dublin, Ireland) has enabled a parietooccipital (P-O) burr hole approach to the frontal horns. We compare shunt placement and revisions required for patients with slit ventricles who had shunts inserted via a P-O approach versus frontal shunt. METHODS: We studied a retrospective cohort of patients with slit ventricles and a ventricular shunt inserted using EM guidance between 2012 and 2018. Slitlike ventricles were defined as the widest point of the lateral ventricle <3 mm. Outcome measures included placement accuracy and survival using the Kaplan-Meier curve. Optimal final catheter tip location was considered to be the frontal horn of the ipsilateral lateral ventricle. RESULTS: Eighty-two patients (77 female, 5 male) aged 34.9 ± 10.8 years (mean ± standard deviation) had ventricular shunts inserted for idiopathic intracranial hypertension (n = 63), chiari/syrinx (n = 8), congenital (n = 10), and pseudomeningocele (n = 1). Of those identified, 35 had primary P-O shunts and 46 had frontal shunts. Overall, 94% of cases had the catheter tip sitting in the frontal horn. The P-O approach was just as accurate as the frontal approach. Eight P-O shunts and 9 frontal shunts required revision over a 60-month period. There was no significant different in shunt survival between the 2 approaches (P = 0.37). CONCLUSIONS: EM-guided placement has enabled the P-O approach to be as safe and with equivalent survival to frontal approach. The accuracy of shunt placement between the 2 approaches was similar.

CSF-diverting shunts: Implications for abdominal and pelvic surgeons; a review and pragmatic overview.

The optimal management of patients with ventriculoperitoneal or lumboperitoneal shunts undergoing abdominal or pelvic surgery for unrelated reasons is often unclear due to the paucity of guidelines in this field. In this review, we outline key issues in managing these patients. Specifically, we address issues relating to pre-operative planning, avoidance of shunt-related complications such as infection and malfunction, and specific management of neurological symptoms in the post-operative period. A retrospective study was carried out analysing correspondence between general surgeons and a specialist hydrocephalus unit over a 4-year period relating to management of patients with ventriculoperitoneal and lumboperitoneal shunts undergoing abdominal or pelvic surgery. A literature review was carried out to identify available evidence in this field. 30 queries from general surgeons were identified comprising 12 main themes. 16 relevant publications were identified. We summarised these to answer these queries. The management of shunted patients may present challenges and uncertainties in an abdominal or pelvic surgery setting. This paper provides guidelines and clarity in this field by discussing and summarising reported data in the literature.

Neural Circuitry: Architecture and Function-A Fiber Dissection Study.

OBJECTIVE: White fiber dissection using a gyrus-based approach was performed to study the various associations, commissural, and projection fiber bundles of the brain. METHODS: Ten previously frozen and formalin-fixed cadaveric human brains were included. The fiber dissection techniques described by Klingler were used. The primary dissection tools were thin handmade wooden spatulas and curved metallic spatulas with tips of various sizes. The fibers were studied by the naked eye and with the use of magnification. The various fiber bundles were studied using a gyrus-based approach. The dissection was performed through each named gyrus, and the fiber tracts encountered during dissection were identified, and their relationship to other adjacent fiber bundles was studied. RESULTS: From our dissections, the white fibers of the brain were divided architecturally into 5 groups-4 horizontal groups and 1 vertical group. The 4 horizontal groups were the superficial, middle, deep, and central groups. The association fibers constituted the superficial, middle, and deep groups. The commissural fibers formed the central group, and the projection fibers formed the vertical group. The course of the fiber bundles and their functional co-relationship were determined. CONCLUSIONS: When planning the surgical trajectory, knowledge of the location of white matter tracts is essential to help minimize the occurrence of postoperative deficits. Fiber dissection using the Klingler technique is useful in gaining an understanding of the complex 3-dimensional nature of these white matter tracts and can provide a valuable resource in neurosurgical training.

Stem cell therapy in spinal cord injury: Hollow promise or promising science?

Spinal cord injury (SCI) remains one of the most physically, psychologically and socially debilitating conditions worldwide. While rehabilitation measures may help limit disability to some extent, there is no effective primary treatment yet available. The efficacy of stem cells as a primary therapeutic option in spinal cord injury is currently an area under much scrutiny and debate. Several laboratory and some primary clinical studies into the use of bone marrow mesenchymal stem cells or embryonic stem cell-derived oligodentrocyte precursor cells have shown some promising results in terms of remyelination and regeneration of damaged spinal nerve tracts. More recently,laboratory and early clinical experiments into the use of Olfactory Ensheathing Cells, a type of glial cell derived from olfactory bulb and mucosa have provided some phenomenal preliminary evidence as to their neuroregenerative and neural bridging capacity. This report compares and evaluates some current research into selected forms of embryonic and mesenchymal stem cell therapy as well as olfactory ensheathing cell therapy in SCI, and also highlights some legal and ethical issues surrounding their use. While early results shows promise, more rigorous large scaleclinical trials are needed to shed light on the safety, efficacy and long term viability of stem cell and cellular transplant techniques in SCI.

Double insurance transfacetal screws for lumbar spinal stabilization.

AIM: The authors report experience with 14 cases where two screws or "double insurance" screws were used for transfacetal fixation of each joint for stabilization of the lumbar spinal segment. The anatomical subtleties of the technique of insertion of screws are elaborated. MATERIALS AND METHODS: During the period March 2011 to June 2014, 14 patients having lumbar spinal segmental instability related to lumbar canal stenosis were treated by insertion of two screws into each articular assembly by transfacetal technique. After a wide surgical exposure, the articular cartilage was denuded and bone chips were impacted into the joint cavity. For screw insertion in an appropriate angulation, the spinous process was sectioned at its base. The screws (2.8 mm in diameter and 18 mm in length) were inserted into the substance of the medial or inferior articular facet of the rostral vertebra via the lateral limit of the lamina approximately 6-8 mm away from the edge of the articular cavity. The screws were inserted 3 mm below the superior edge and 5 mm above the inferior edge of the medial (inferior) facets and directed laterally and traversed through the articular cavity into the lateral (superior) articular facet of the caudal vertebra toward and into the region of junction of base of transverse process and of the pedicle. During the period of follow-up all treated spinal levels showed firm bone fusion. There was no complication related to insertion of the screws. There was no incidence of screw misplacement, displacementor implant rejection. CONCLUSIONS: Screw insertion into the firm and largely cortical bones of facets of lumbar spine can provide robust fixation and firm stabilization of the spinal segment. The large size of the facets provides an opportunity to insert two screws at each spinal segment. The firm and cortical bone material and absence on any neural or vascular structure in the course of the screw traverse provides strength and safety to the process.