Theoretical analysis of the pathophysiology of syringomyelia associated with adhesive arachnoiditis

OBJECTIVE: To apply a theoretical model to analyse the derangement of cerebrospinal fluid (CSF) dynamics in syringomyelia associated with adhesive arachnoiditis. METHODS: An electrical circuit model of CSF dynamics in the spine was used. With this model, the derangement of CSF dynamics in adhesive arachnoiditis was simulated. The effects of various surgical procedures were then analysed, such as syringo-subarachnoid shunting, subarachnoid bypass, and foramen magnum decompression. RESULTS: When CSF flow in the subarachnoid space was obstructed at a certain point, the pressure inside the spinal cord increased in the segment immediately distal to the blockage. This location of increased pressure corresponded to the preferred site of syrinx formation in adhesive arachnoiditis. Syringo-subarachnoid shunting, subarachnoid bypass, and foramen magnum decompression were all effective at reducing this pressure gradient. CONCLUSIONS: Blockage of the spinal subarachnoid CSF pathway produces a relative increase in the pressure inside the spinal cord distal to the blockage point. Repetitive formation of this pressure gradient then induces CSF leakage into the spinal parenchyma, leading to the formation of syringomyelia. Using this model, alternative surgical procedures could be suggested that might be effective in treating this disease.     

Spinal syringomyelia following subarachnoid hemorrhage

Subarachnoid blood has been reported as a cause of chronic spinal arachnoiditis. Although syringomyelia has been thought to be caused by spinal arachnoiditis, reports of syringomyelia following aneurysmal subarachnoid hemorrhage (SAH) are very rare. We describe two patients with syringomyelia associated with chronic spinal arachnoiditis following SAH. From January 2001 to December 2010, 198 patients with aneurysmal SAH were treated at Kinki University School of Medicine. Two of the 198 patients had syringomyelia following aneurysmal SAH; thus the rate of syringomyelia associated with aneurysmal SAH was 1.0%. Patient 1 was a 54-year-old woman who presented with back pain, back numbness and gait disturbance 20 months after SAH. Her MRI revealed syringomyelia of the spinal cord from C2 to T10. She underwent shunting of the syrinx to the subarachnoid space. Patient 2 was a 49-year-old man, who was admitted to the hospital with headache, diplopia, hoarseness, dysphagia and ataxia five months after SAH. MRI revealed syringomyelia from the medulla oblongata to C6, and an enlargement of the lateral and fourth ventricles. After foramen magnum decompression and C1 laminectomy, a fourth ventricle-subarachnoid shunt was placed by insertion of a catheter. Spinal arachnoiditis and spinal syringomyelia are rare but important chronic complications after SAH.     

The presyrinx state due to adhesive arachnoiditis: a case report]

We report a 66-year-old woman with a presyrinx state due to adhesive arachnoiditis. She had a history of subarachnoid hemorrhage one year ago. She became aware of gait disturbance and abnormal sensation at the chest 6 months ago. Neurological examination revealed weakness of the both lower extremities and sensory disturbance below the T6 level. MR images of the thoracic spine revealed swelling of the thoracic cord at the T3-4 level, with an intramedullary hyperintensity on T2 weighted images (WI) and hypointensity on T1-WI. The intramedullary hypointensity on T1-WI was less than the CSF intensity. In addition, the thoracic cord lower than T5 level was compressed by an arachnoid cyst in the spinal canal. The preoperative diagnosis was the presyrinx state due to adhesive arachnoiditis. An operation for detachment of arachnoidal adhesion and restoration of CSF flow pathway was performed. After one month from the operation, neurological findings were improved. Postoperative MR images revealed improvement of swelling of the thoracic cord and intramedullary abnormal intensity. The arachnoid cyst in the spinal canal was decreased in the size. The presyrinx state is recently recognized condition before the formation of syringomyelia and that is known to resolve with proper treatment. We wish to emphasize we could prevent a progression to syringomyelia by a proper treatment for the presyrinx state.     

Novel surgical management of spinal adhesive arachnoiditis by arachnoid microdissection and ventriculo-subarachnoid shunting

Spinal cord tethering and cerebrospinal fluid (CSF) flow disturbance are two major features in the pathophysiology of spinal adhesive arachnoiditis. We hypothesized that insufficient CSF supply to the surgically untethered spinal cord may be one of the causes of the typical post-operative recurrent extensive lesion. We report a patient with extensive spinal adhesive arachnoiditis, who was successfully treated using a novel surgical technique consisting of two procedures. First, microdissection of the thickened adherent arachnoid was performed to resolve spinal cord tethering. Next, a ventriculo-subarachnoid shunt was placed to provide sufficient flow of CSF. Clinical improvement was sustained for at least 22 months after surgery. The present surgical procedure may improve clinical outcome in patients with longitudinally extensive spinal adhesive arachnoiditis.     

Experimental syringomyelia in rabbits and rats after localized spinal arachnoiditis]

In order to produce syringomyelia, localized arachnoiditis was created in adult New Zealand albino rabbits and Wistar rats by the injection of kaolin into the thoracic spinal subarachnoid space and incision of the dura mater of the thoracic spinal cord. The rabbits and rats were divided into 3 groups; the control group, dural incision group (DG) and kaolin injection group (KG). Each rabbit was sacrificed at 4, 8, 12 and 16 weeks after the operation. Each rat was sacrificed at 8 and 16 weeks after the operation. Cavity formation in the cord of all rabbits was examined by ultrasound. All animals were perfused with 10% neutral beffered formalin at 150 cm H2O pressure, and histological examination was performed with Luxol fast blue (LFB) and hematoxylin and eosin (H&E) stains. Results obtained: (1) Cavity formation was noted in 6 of 16 DG of rabbit (37.5%), 5 of 16 KG of rabbit (31.2%) and 2 of 9 KG of rat (22.2%) with histological verification. With use of ultrasound, cavity was noted in 3 of 16 DG rabbits (12.5%) and 2 of 16 KG rabbits (18.8%). (2) Cavity formation was present in the cord adjacent to the marked adhesive arachnoiditis both in rabbits and in rats. (3) Cavity was noted in the ischemic area. (4) In 2 rabbits in which kaolin encircled whole surface of the spinal cord, hydromyelia was formed communicating with enlarged central canal caudad from the kaolin subarachnoid block. (5) Histological examination showed obliteration or narrowing of lumen of the small pial vessels involved in the adhesive arachnoiditis. In the cord parenchyma adjacent to the arachnoiditis, multiple spots of demyelination due secondary to ischemia demonstrated by LFB stain were noted. On the other hand, in the cord with the pia-arachnoid remained uninvolved, no demyelination was observed. (6) Localized adhesive arachnoiditis consisted of proliferation of fibrous tissue, lymphocytic infiltration and obliterating processes of small pial vessels involved in it. These data suggest that the cavitation within the cord would be induced by the ischemia, and hydromyelia would be produced by the pressure dissociation between the spinal subarachnoid space and the central canal.     

脊髓蛛网膜炎合并脊髓空洞的显微手术治疗

目的探讨脊髓蛛网膜炎合并脊髓空洞的显微手术治疗方法。方法回顾性分析经显微外科手术治疗的15例脊髓蛛网膜炎合并脊髓空洞病人的临床资料。根据脊髓蛛网膜炎症黏连的特点分为3型：I型（弥漫黏连型）10例,Ⅱ型（局限黏连型）3例,Ⅲ型（囊肿型）2例。I型行脊髓空洞一胸腔分流术,Ⅱ型行脊髓黏连松解术,Ⅲ型行囊肿探查切除术。结果术后症状明显改善13例,同术前2例。MRJ复查显示：脊髓空洞缩小12例,消失1例,同术前2例。13例术后随访8个月～3年,症状改善9例,同术前3例,加重1例。结论显微手术是治疗脊髓蛛网膜炎合并脊髓空洞的有效方法,根据分型选择合适的显微手术治疗方案,治疗效果较好。     

Experimental communicating syringomyelia in dogs after cisternal kaolin injection: Part 2. Pressure studies

Pressure measurements in cerebrospinal fluid have been made from the ventricles and the spinal subarachnoid space in dogs made hydrocephalic by intracisternal injections of kaolin. Raised intraventricular pressure has been confirmed in the ventricles. The spinal pressure is usually markedly different from that in the head, confirming that the arachnoiditis produced around the cistern isolates the spinal subarachnoid space from the CSF in the head. Pulsatile pressures have been investigated specifically and the interrelationship between the pulsation and baseline pressures in the development of communicating syringomyelia discussed. There are differences between these experimental animals and the human disease, particularly in the baseline pressures which are usually equal in the head and the spine of humans at rest even in cases with syringomyelia.     

Syringomyelia and arachnoiditis.

Five patients with chronic arachnoiditis and syringomyelia were studied. Three patients had early life meningitis and developed symptoms of syringomyelia eight, 21, and 23 years after the acute infection. One patient had a spinal dural thoracic AVM and developed a thoracic syrinx 11 years after spinal subarachnoid haemorrhage and five years after surgery on the AVM. A fifth patient had tuberculous meningitis with transient spinal cord dysfunction followed by development of a lumbar syrinx seven years later. Arachnoiditis can cause syrinx formation by obliterating the spinal vasculature causing ischaemia. Small cystic regions of myelomalacia coalesce to form cavities. In other patients, central cord ischaemia mimics syringomyelia but no cavitation is present. Scar formation with spinal block leads to altered dynamics of cerebrospinal fluid (CSF) flow and contributes to the formation of spinal cord cystic cavities.     

Syringomyelia and tethered cord in children

Introduction

The presence of syringomyelia varies in patients with different forms of dysraphism; from 21 % to 67 %. Only around 60 % of patients with syringomyelia is likely to experience symptoms related to it.

Pathophysiology

Many theories have been outlined for the creation of syringomyelia. The one most applicable to tethered cord dictates that tensile radial stress may create a syrinx in a previously normal cord tissue and transiently lower pressure may draw in interstitial fluid, causing the syrinx to enlarge if fluid exit is inhibited. In addition, arachnoiditis increases flow resistance in the spinal subarachnoid space, altering temporal CSF pulse pressure dynamics, which promotes entry of CSF in to the spinal cord.

Clinical presentation

There is a significant overlap between the symptoms that are due to tethered cord and syringomyelia, both in newly presenting patients with coexisting syringomyelia, and in previously treated patients who during follow-up present recurrent symptoms and a new syringomyelia cavity.

Treatment

The treatment of patients with tethered cord and syringomyelia is directed towards untethering the cord from its most caudal region upwards and restoring spinal anatomy with reestablishment of unobstructed CSF flow in the subarachnoid space. Only if complete untethering has been ensured and syringomyelia deteriorates, then surgical treatment can be directed against the syrinx. In patients with spinal dysraphism and coexisting hydrocephalus, radiological presentation of new syringomyelia or deterioration of previously known syringomyelia may signify shunt obstruction “until proven otherwise”.

Conclusion

In most occasions, satisfactory cord untethering addresses the development of syringomyelia.     

Progress in syringomyelia

Syringomyelia management is showing some progressive improvements following surgical methods of investigation and treatment. Investigation of simultaneous pressure changes in the cerebrospinal fluid pathways has illustrated the importance of craniospinal pressure dissociation in impacting the cerebellar and medullary tissues in the foramen magnum in hindbrain related syringomyelia. Such pressure differences may be referred to as 'suck' and similar changes are to be found in non-hindbrain related forms of syringomyelia such as those associated with spinal arachnoiditis. When cavities have formed then impulsive movements may occur with them and enlargement of the cavities may be continued by sloshing of the fluid within them. Investigations have been improved following the widespread use of water soluble contrast media and CT scanning with reconstructions after myelography.

A definite relationship between birth injury and hindbrain related syringomyelia has been established especially with cases showing arachnoiditis. The nature of the relationship to hindbrain hernia and basilar invagination remains unclear. Magnetic resonance imaging holds great promise particularly in showing hindbrain deformation in new-born babies, showing whether or not a communication commonly exists between the fourth ventricle and the cavities within the spinal cord in early childhood and also in outlining the changes in the spinal cord in the presence of acute traumatic paraplegia. Treatment still relies upon valved ventricular to extrathecal shunts for hydrocephalus, cranio-vertebral decompression to prevent suck and drainage of the syrinx in appropriate cases. Syrinx to extrathecal shunting may be preferred to shunts to the subarachnoid space. The peritoneum and the pleura are favoured sites and a valve is not necessary. The advances for the future may depend on earlier diagnosis and greater understanding of the mechanisms of pathogenesis in which MRI seems likely to play an increasingly important part.     

Arachnoiditis ossificans with progressive syringomyelia and spinal arachnoid cyst.

We present a 30-year-old man with progressive spastic paraparesis. Spinal imaging revealed extensive calcification of the thoracic cord and cauda equina arachnoid, an intradural extramedullary cyst and evidence of rapidly progressing syringomyelia. Radiological diagnosis was arachnoiditis ossificans and an attempt at surgical decompression was made because of progressive neurologic deterioration. Due to tenacious adhesion of the calcified plaques to the cord and roots, only cyst drainage was achieved; the patient had no clinical improvement. A literature review revealed only two other cases reported in the literature with co-existence of arachnoiditis ossificans and syringomyelia. In none of the previous cases was there an intradural extramedullary arachnoid cyst, nor did the syrinx progress in such a rapid fashion. An attempt is made to explain possible pathophysiological mechanisms leading to this unusual pathology.     

与Chiari畸形或脊髓损伤无关的脊髓空洞症的外科治疗（英文）

PURPOSE Syringomyelia is a misleading disease since the problem always lies elsewhere.Arachnoiditis,because it is radiographically difficult to discern,is an especially insidious cause.To better guide selection from among surgical treatment options for syringomyelia,we reviewed our case series of patients without Chiari malformation or spinal injury.METHODS Excluding syringomyelia due to Chiari malformation,spinal cord injury,and tumors,32 patients(mean age 44 years)were operated on between 1995 and 2013and followed up for a mean of 53.8 months.Presumed causes at diagnosis,clinical and radiological findings,type of operation,clinical and radiological outcome were reviewed.RESULTS Duration of clinical history varied widely(range 6-164 months).Clinical assessment was based on the McC ormick classification(15 independent,17 dependent).Causes included birth trauma,pyogenic meningitis,tuberculous meningitis,postoperative scarring,dysraphism,and basilar impression.Treatment was local decompression with arachnoid lysis and shunts.Hindbrain-related syringomyelia was differentiated from non hindbrain-related syringomyelia.Hindbrain arachnoiditis was significantly associated with radiological findings at the foramen magnum(P=0.01)and craniocervical decompression(P0.03),with good clinical and radiological outcome at 6 months and later follow-up controls(P=0.02),whereas uneven results were observed in cases of non-hindbrain arachnoiditis.CONCLUSIONS To remove the cause of syringomyelia,surgical planning will rely on thorough clinical history and accurate imaging to determine the site of cerebrospinal fluid obstruction.Craniocervical decompression to dissect basal arachnoiditis in the posterior fossa can be recommended in hindbrain syringomyelia.Treatment of non-hindbrain arachnoiditis is more controversial,probably owing to uncertainties about the extent of adhesions.     

Treatment of syringomyelia with a syringosubarachnoid shunt

The surgical results in 40 patients with syringomyelia, treated with a syringosubarachnoid shunt or other procedures are reviewed. The principal indication for surgery was that of significant neurological deterioration. There were 12 patients with idiopathic syringomyelia without tonsillar ectopia, 12 with an associated Chiari malformation, 11 with post-traumatic syringomyelia and five patients with spinal arachnoiditis. There were 38 syringosubarachnoid shunts performed in 35 patients, and an excellent or good result was achieved in 26 patients (74.3%). In terms of the type of syringomyelia, the best results were obtained in the idiopathic group without tonsillar ectopia and in the post-traumatic group. A short duration of pre-operative symptoms favoured a better outcome, and in our opinion, early surgical treatment is indicated for all patients with neurological deterioration. All eight patients in whom a posterior fossa decompression was performed as the initial surgical procedure required a second operation, either a syringosubarachnoid or syringoperitoneal shunt to achieve neurological improvement or stabilization. Thus, the syringosubarachnoid shunt is an effective therapeutic modality for patients with syringomyelia, particularly for the idiopathic and post-traumatic groups. More than one surgical procedure may be required to achieve cessation of deterioration. Overall, excellent or good results were achieved in 29 (72.5%) of the 40 patients.     

Chiari畸形伴脊髓空洞症的微创手术治疗

目的探讨Chiari畸形并脊髓空洞症的微创外科手术治疗方法。方法回顾性分析74例患者微创手术治疗情况。微创手术治疗74例,均行后颅窝小骨窗减压,下疝小脑扁桃体切除,松解蛛网膜下腔的粘连,开放正中孔至第四脑室及小脑延髓侧池,改善蛛网膜下腔脑脊液循环,原位缝合硬脑膜。结果术后临床症状消失和改善者68例,无变化6例。随访56例,脊髓空洞明显缩小。结论微创手术是治疗Chiari畸形并脊髓空洞症的有效方法。恢复蛛网膜下腔的脑脊液循环是治疗的关键。     

Omento-myelo-synangiosis in the management of chronic traumatic paraplegia: case report

A case of traumatic paraplegia, with almost complete motor and sensory loss up to the umbilicus, who had an operation for post traumatic arachnoiditis and diagnosed as having recurrence of arachnoiditis and traumatic syringomyelia and treated by a pedicled omental onlay graft to the spinal cord, is described. The patient made a remarkable recovery and 1 year after surgery he continues to maintain excellent progress. He is now able to walk with support and is completely independent. It is suggested that chronic paraplegics should be assessed for possible arachnoiditis and traumatic syringomyelia and if detected an omental transposition be considered as one means of increasing rehabilitation potential.     

Surgical management of syringomyelia: a five year experience in the era of magnetic resonance imaging.

We summarize our experience with 59 consecutive surgically managed cases of syringomyelia (SM) over a 5 year period. All cases had magnetic resonance imaging (MRI) preoperatively and postoperatively. Twenty-eight patients presented with SM and the adult Chiari (Chiari I) malformation (SM-ACM), 6 patients had post traumatic syrinxes, 14 patients had syrinxes associated with an intramedullary neoplasm, 3 patients had syringomyelia associated with spinal arachnoiditis and 8 patients had idiopathic syringomyelia. Holocord syrinxes were more often associated with SM-ACM, while focal syrinxes were associated with posttraumatic, spinal arachnoiditis and neoplastic conditions. In all cases with neoplasms the MRI revealed parenchymal intramedullary signal abnormalities in addition to the syrinx cavity. Posterior fossa decompression with obex plugging (the Gardner operation) was the procedure of choice for SM-ACM and for idiopathic holocord syringomyelia. Exploration and drainage of the syrinx with or without shunting was carried out mainly for focal syrinxes associated with trauma and neoplasm. Patients with SM-ACM responded well to posterior fossa decompression with satisfactory results in 24/28 patients. Idiopathic SM is probably a forme fruste of SM-ACM and when treated with the Gardner procedure showed good results in all 8 patients. Posttraumatic and neoplastic SM had the least predictable results with surgery. The disappearance of the syrinx on postoperative MRI correlated well with a good surgical outcome.     

Progress in syringomyelia

Syringomyelia management is showing some progressive improvements following surgical methods of investigation and treatment. Investigation of simultaneous pressure changes in the cerebrospinal fluid pathways has illustrated the importance of craniospinal pressure dissociation in impacting the cerebellar and medullary tissues in the foramen magnum in hindbrain related syringomyelia. Such pressure differences may be referred to as 'suck' and similar changes are to be found in non-hindbrain related forms of syringomyelia such as those associated with spinal arachnoiditis. When cavities have formed then impulsive movements may occur with them and enlargement of the cavities may be continued by sloshing of the fluid within them. Investigations have been improved following the widespread use of water soluble contrast media and CT scanning with reconstructions after myelography. A definite relationship between birth injury and hindbrain related syringomyelia has been established especially with cases showing arachnoiditis. The nature of the relationship to hindbrain hernia and basilar invagination remains unclear. Magnetic resonance imaging holds great promise particularly in showing hindbrain deformation in new-born babies, showing whether or not a communication commonly exists between the fourth ventricle and the cavities within the spinal cord in early childhood and also in outlining the changes in the spinal cord in the presence of acute traumatic paraplegia. Treatment still relies upon valved ventricular to extrathecal shunts for hydrocephalus, cranio-vertebral decompression to prevent suck and drainage of the syrinx in appropriate cases. Syrinx to extrathecal shunting may be preferred to shunts to the subarachnoid space. The peritoneum and the pleura are favoured sites and a valve is not necessary. The advances for the future may depend on earlier diagnosis and greater understanding of the mechanisms of pathogenesis in which MRI seems likely to play an increasingly important part.     

Syringoperitoneal shunt for treatment of cord cavitation.

A series of twenty-nine patients with cord cavitation were treated by syringoperitoneal shunt. Twenty-two of them showed improvement after operation, five were unchanged and two worsened. Operation was performed in patients with post-traumatic cystic myelopathy, idiopathic syringomyelia, intramedullary tumours associated with cysts, and patients who had developed cystic myelopathy in association with spinal arachnoiditis. Pain improved in twenty patients, sensory symptoms and signs in eleven and weakness in ten.     

Diagnosis of syringomyelia and its classification on the basis of symptoms, radiological appearance, and causative disorders

Although it is easier to accurately diagnose syringomyelia with the advent of magnetic resonance (MR) imaging, syringomyelia still poses challenges to clinicians because of its complex symptomatology, uncertain pathogenesis and multiple treatment options. Here, we propose criteria for classification of syringomyelia not related to those associated with spinal intramedullary tumors. The classification aims to distinguish between the presyrinx state and syringomyelia, between asymptomatic and symptomatic syringomyelia and to clarify the associated disorders such as Chiari malformations, spinal arachnoiditis and spinal cord trauma. Diagnostic criteria for Chiari I and II malformations with MR imaging were also defined. Several hypotheses proposed to explain the pathogenesis of syringomyelia associated with Chiari I malformation were reviewed. A questionnaire survey on syringomyelia based on the proposed criteria conducted between November 2009 and April 2010 in Japan revealed that 160 (22.6%) of the 708 patients were asymptomatic. Chiari I malformation was the most frequent causative disorder (48.3%), followed by spinal arachnoiditis (15.8%). The proposed criteria for classification of syringomyelia will facilitate a nationwide survey of syringomyelia in Japan. Such a survey will inform us of its prevalence and prognosis more precisely, and enable us to build a reliable database that may help determine the optimal treatment for the disease in the future.     

Surgical treatment of thoracic arachnoiditis with multiple subarachnoid cysts caused by epidural anesthesia

We report on a 36 year-old woman who had sensorimotor and sphincter dysfunction 0.5 day after having an epidural anesthesia to deliver her baby. The patients' neurological deficits recovered gradually and she could walk without support 1.5 months after the operation. However, her neurological function deteriorated 4 months after anesthesia and a magnetic resonance imaging (MRI) study revealed spinal arachnoiditis with multiple subarachnoid cysts at the T5-7 levels. Surgical treatment consisted of lysis of adhesions and wide opening of the subarachnoid cysts. Her motor function improved after operation and she could walk without support after a 1 year follow-up. However, her sphincter and sensory abnormalities persisted for the most part. The literature on the surgical treatment of arachnoiditis with myelopathy is reviewed and the surgical indications are discussed.