Decoding Chiari Malformation and Syringomyelia: From Epidemiology and Genetics to Advanced Diagnosis and Management Strategies

Chiari Malformation and Syringomyelia are neurosurgical entities that have been the subject of extensive research and clinical interest. Globally prevalent, these disorders vary demographically and have witnessed evolving temporal trends. Chiari Malformation impacts the normal cerebrospinal fluid flow, consequently affecting overall health. Key observations from canine studies offer pivotal insights into the pathogenesis of Syringomyelia and its extrapolation to human manifestations. Genetics plays a pivotal role; contemporary knowledge identifies specific genes, illuminating avenues for future exploration. Clinically, these disorders present distinct phenotypes. Diagnostically, while traditional methods have stood the test of time, innovative neurophysiological techniques are revolutionizing early detection and management. Neuroradiology, a cornerstone in diagnosis, follows defined criteria. Advanced imaging techniques are amplifying diagnostic precision. In therapeutic realms, surgery remains primary. For Chiari 1 Malformation, surgical outcomes vary based on the presence of Syringomyelia. Isolated Syringomyelia demands a unique surgical approach, the effectiveness of which is continually being optimized. Post-operative long-term prognosis and quality of life measures are crucial in assessing intervention success. In conclusion, this review amalgamates existing knowledge, paving the way for future research and enhanced clinical strategies in the management of Chiari Malformation and Syringomyelia.

Tetraventricular hydrocephalus with aqueductal flow void: an overlooked entity having consistent improvement following endoscopic third ventriculostomy

BACKGROUND

Tetraventricular Hydrocephalus (TetHCP) is a heterogeneous group of cerebrospinal fluid (CSF) flow disorders having varying success rates with Endoscopic third ventriculostomy (ETV). This is report on the efficacy and rationale of ETV in a specific subset of primary TetHCP with aqueductal CSF flow voids.

METHODS

Patients of primary acquired TetHCP presenting with increasing head size and/or headache having aqueductal CSF flow void on sagittal Magnetic Resonance Imaging (MRI) were included in this study. All of them underwent ETV. All patients were evaluated for clinical improvement & MRI at 3 months, and need for any additional procedure, in contrast to those without CSF flow void. The pathophysiology of hyperdynamic CSF circulation and its correlation to ETV was further reviewed.

RESULTS

Eleven patients had tetraventricular hydrocephalus and aqueductal flow void, with age ranging from 10 months to 59 years. Two patients who could undergo quantitative flow study confirmed the hyperdynamic flow across the aqueduct. Following ETV, all showed clinical improvement. MRI at 3 months showed CSF flow void across the third ventricular stoma in addition to across the aqueduct. None of these patients required any redo procedures for a mean follow-up of 39.2 months. In contrast, there was 30% failure rate after ETV among 10 patients of tetraventricular hydrocephalus without aqueductal flow void.

CONCLUSION

Tetraventricular hydrocephalus with aqueductal CSF flow void may be a unique entity with hyperdynamic CSF circulation and relative resistance at fourth ventricular outlets. ETV is highly efficacious in these patients, resulting in consistent clinico-radiological improvement.

Fourth ventricle to spinal subarachnoid space stenting in pediatric patients with refractory syringomyelia: case series and systematic review

A series of 5 patients treated with the fourth ventricle to spinal subarachnoid space stent (FVSSS) is presented. Indication for surgery, surgical technique, pre-operative and post-operative images, and outcome are analyzed. A systematic review of the pertinent literature has also been performed. This is a retrospective cohort review of a series of 5 consecutive patients with refractory syringomyelia who underwent a fourth ventricle to spinal subarachnoid space shunt surgery. The surgical indication was based on the presence of refractory syringomyelia in patients already treated for Chiari malformation or in patients who developed scarring at the level of the outlets of the fourth ventricle following posterior fossa tumor surgery. The mean age at FVSSS was 11.30 ± 5.88 years. Cerebral MRI revealed crowded posterior fossa, with a membrane at the level of the foramen of Magendie. Spinal MRI showed syringomyelia in all patients. Before surgery, the averages of the craniocaudal and the anteroposterior diameter were 22.66 and 1.01 cm, respectively, whereas the volume was 28.16 cm³. The post-operative period was uneventful in 4 out of 5 patients; one child died on the 1st post-operative day due to complications unrelated to surgery. In remaining cases, syrinx marked improvement. The post-operative volume was 1.47 cm³ with an overall reduction of 97.61%. With regard to literature, 7 articles with a total of 43 patients were analyzed. After FVSSS, syringomyelia reduction was observed in 86.04% of cases. Three patients underwent reoperation due to syrinx recurrence. Four patients presented a catheter displacement, one a wound infection and meningitis and one CSF leak requiring placement of a lumbar drain. FVSSS is highly effective in restoring CSF dynamics, with dramatic improvement of syringomyelia. In all our cases, the volume of the syrinx was reduced by at least 90%, with improvement/resolution of accompanying symptomatology. This procedure should be reserved to patients in which other causes of gradient pressure between the fourth ventricle and subarachnoid space are excluded, for example, tetraventricular hydrocephalus. Surgical procedure is not simple, because it requires meticulous microdissection of cerebello-medullary fissure and upper cervical spine, in already operated patients. To avoid migration of the stent, it should be carefully sutured to the dura mater or thick arachnoid membrane.

Cerebrospinal Fluid Hydrodynamics in Chiari I Malformation and Syringomyelia: Modeling Pathophysiology

Anatomic MRI, MRI flow studies, and intraoperative ultrasonography demonstrate that the Chiari I malformation obstructs CSF pathways at the foramen magnum and prevents normal CSF movement through the foramen magnum. Impaired CSF displacement across the foramen magnum during the cardiac cycle increases pulsatile hindbrain motion, pressure transmission to the spinal subarachnoid space, and the amplitude of CSF subarachnoid pressure waves driving CSF into the spinal cord. Central canal septations in adults prevent syrinx formation by CSF directly transmitting its pressure wave from the fourth ventricle to the central canal.

Magendie's foramen debridement and catheterisation for the treatment of syringomyelia due to diffuse craniocervical junction arachnoiditis. A case report and technical note

A 36 year old woman was referred to our department for symptomatic lumbar spinal arachnoiditis following an epidural anaesthesia for childbirth. She did not had other known causative factor and she was free of any neurological symptoms before. She rapidly developed lower limbs impairment by compressing intradural lumbar collections and arachnoiditis requiring surgical decompression and subsequently internal cerebrospinal fluid shunting for acute hydrocephalus. Three years and the half later, she developed a severe tetraparesis due to a massive syrinx consecutive to the fourth ventricle outlets obstruction cause by the ongoing diffuse craniocervical junction arachnoiditis. Our aim was to treat all the problems in one step. An open fourth ventriculostomy of the Magendie's foramen with catheter insertion from the fourth ventricle down to the upper cervical subarachnoid space improve both the patient status and imagery.

Assessment of patients with a Chiari malformation type I

Introduction

The prevalence of Chiari malformation type I (CM-I) has been estimated as up to 1% of the general population. The majority of patients are asymptomatic and usually do not need treatment. Symptomatic patients, and some asymptomatic patients with associated conditions, may benefit from further assessment and treatment.

Research question

The aim of this review was to describe the clinical and radiological assessment of patients presenting with a CM-I.

Material and methods

A literature search was performed using the PubMed and Embase databases focused on clinical assessment and imaging techniques used to diagnose CM-I.

Results

Following a complete clinical evaluation in patients with symptomatic CM-I and/or radiologically significant CM-I (tonsillar impaction, resulting tonsillar asymmetry and loss of CSF spaces), MRI of the brain and whole spine enables an assessment of the CM-I and potential associated or causative conditions. These include hydrocephalus, syringomyelia, spinal dysraphism, and tethered cord. Flow and Cine MRI can provide information on CSF dynamics at the craniocervical junction, and help in surgical decision-making. Hypermobility or instability at the upper cervical and craniocervical junction is less common and can be measured with CT imaging and flexion/extension or upright MRI.

Discussion and conclusion

The majority of CM-I detected are incidental findings on MRI imaging of brain or spine, and do not require intervention. Once a radiological diagnosis and concern has been raised, clinical assessment by an appropriate specialist is required. A MRI brain and cervical spine is indicated in all radiologically labelled CM-I. In symptomatic patients or cases of radiologically significant CM-I, MRI of the brain and entire spine is indicated. Further investigations should be tailored to individuals’ needs.

•

A CM-I assessment should include a history and examination and a referral to a specialist.

•

MRI of the brain and spine enables an assessment of the CM-I and potential associated conditions.

•

Flow and Cine MRI can help in surgical decision-making.

Trapped fourth ventricle-treatment options and the role of open posterior fenestration in the surgical management

BACKGROUND

Trapped fourth ventricle (TFV) is a rare and difficult to treat condition. Most patients have a past inciting event (infection, IVH, trauma) and history of prior CSF diversion. The symptoms are due to the mass effect on brainstem and cerebellum. Rarely, TFV can also be associated with syrinx formation due to a dissociated craniospinal CSF flow near the fourth ventricle outlets. We present our experience and outcomes of open posterior fenestration in 11 cases, along with an overview of the surgical management of TFV.

METHODS

Between 2011 and 2018, 11 patients of TFV were operated by the posterior approach fenestration of the fourth ventricle outlets and arachnoid dissection. The clinical and radiological findings of the patients were retrieved from the hospital database. The surgical technique is described in detail. The patients' neurological status and imaging findings in the follow-up were recorded and compared.

RESULTS

The average age of the patients was 23.55 years. The most common presenting symptoms were headache (9/11) and gait imbalance (7), with TB meningitis being the commonest etiology. Ten patients had a history of prior CSF diversion with two presenting with shunt malfunction. Mean follow-up duration was 33.33 months. The improvement in neurological status was observed in 9/11 patients, 2 remained status quo. On follow-up imaging, 8/11 (72.72%) patients had a decrease in the size of TFV while syrinx improved in 3/5 (60%).

CONCLUSION

Multiple surgical approaches have been described for TFV. Endoscopic fourth ventriculostomy with aqueductoplasty is gaining popularity in the past two decades. However, an open posterior fenestration of the midline fourth ventricle outlet (magendieplasty) along with sharp arachnoid dissection (adhesiolysis) along the cerebello-medullary cisterns and paracervical gutters is relatively simple and provides physiological fourth ventricular CSF outflow. This is especially useful in TFV with syrinx as the craniospinal CSF circulation is established.