Foramen magnum decompression for syringomyelia associated with basilar impression and Chiari I malformation--report of three cases.

Anterior or posterior decompression of the foramen magnum was performed in three patients with syringomyelia associated with basilar impression and Chiari I malformation. The operative results were evaluated using the pre- and postoperative magnetic resonance (MR) images. Two patients with combined anterior and posterior cervicomedullary compression due to basilar impression and tonsillar descent received suboccipital craniectomy, upper cervical laminectomy, and dural plasty without any intradural manipulations via the posterior approach. One patient with prominent anterior cervicomedullary compression due to basilar impression and a sharp clivoaxial angle was operated on by the transoral anterior approach. Postoperatively, all patients showed a sustained shrinkage of the syrinx and rounding of the flattened cerebellar tonsils. Two patients showed upward movement of the herniated tonsils. All patients had improved symptoms during 2-4 years follow-up. Treatment of syringomyelia associated with basilar impression and Chiari I malformation requires more efficient decompressive procedures at the foramen magnum based on neurological and MR findings.     

Syringomyelia associated with arachnoid septum at the craniovertebral junction, contradicting the currently prevailing theory of syringomyelia formation

Despite a number of various hypotheses in the literature, the pathophysiology of syringomyelia is still not well understood. In this article, we report two cases of cervical syringomyelia not associated with Chiari I malformation. Both cases had a septum-like structure in the subarachnoid space on the dorsal side of the cord at the craniovertebral junction. Cardiac-gated phase-contrast cine-mode magnetic resonance imaging (MRI) demonstrated decreased cerebrospinal fluid (CSF) flow on the dorsal side of the spinal cord. Surgical excision of this septum, restoring the CSF flow, resulted in a prompt reduction of the syrinx size in both cases. Findings in these cases contradict the currently prevailing hypothesis of syrinx formation that postulate that the piston-like movement of the cerebellar tonsils enhance the pulsatile CSF flow in the spinal subarachnoid space, driving the CSF into the syrinx through the perivascular space of Virchow and Robin. The authors propose that a mechanism based on the decreased pulsatile CSF flow in the spinal subarachnoid space will be more suitable as a hypothesis in studying the pathophyisiology of syringomyelia. These cases also provide an important lesson in managing the patients with syringomyelia not associated with Chiari I malformation.     

Hiccups attributable to syringobulbia and/or syringomyelia associated with a Chiari I malformation: case report

OBJECTIVE AND IMPORTANCE: Approximately 20 to 50% of patients with syringomyelia associated with Chiari malformations exhibit cranial nerve or cerebellar symptoms. However, hiccups represent a rare clinical manifestation of this disorder. We report a case of intractable hiccups resulting from syringobulbia associated with a Chiari I malformation, which was successfully treated with foramen magnum decompression. CLINICAL PRESENTATION: We report the case of a patient who presented with syringomyelia and syringobulbia associated with a Chiari I malformation, manifested as intractable hiccups and neurological deficits. Magnetic resonance imaging scans demonstrated syringobulbia in the dorsal medullary region and a large cervical syrinx from C2 to C6-C7, associated with a Chiari I malformation. INTERVENTION: Foramen magnum decompression and a C1 laminectomy were performed. One month later, the intractable hiccups disappeared and the neurological symptoms demonstrated improvement. CONCLUSION: Postoperative magnetic resonance imaging scans demonstrated enlargement of the subarachnoid space in the posterior fossa and disappearance of the syringobulbia. There has been no recurrence of intractable hiccups and syringobulbia in 6 months after surgery. Magnetic resonance imaging of the brainstem is an important diagnostic procedure for intractable hiccups, because syringobulbia associated with a Chiari malformation represents a surgically treatable disorder, although the incidence is low.     

Resolution of tonsillar herniation and syringomyelia after supratentorial tumor resection: case report and review of the literature

OBJECTIVE AND IMPORTANCE: The pathophysiological features of syringomyelia are not yet entirely understood. We present a case of a supratentorial mass causing tonsillar herniation and syringomyelia. CLINICAL PRESENTATION: A 51-year-old woman underwent magnetic resonance imaging for evaluation of progressive headaches. A large parieto-occipital mass was revealed. Herniation of the cerebellar tonsils and a cervical syrinx were also noted. INTERVENTION: A craniotomy was performed without incident. After tumor resection, the tonsils ascended and the syrinx resolved in a 1-year period. CONCLUSION: This case highlights the importance of tonsillar herniation in the pathogenesis of syringomyelia. "Acquired" Chiari malformations and syringomyelia attributable to supratentorial masses may be treated by mass resection alone, without the need for foramen magnum decompression.     

Endoscopic fenestration of posterior fossa arachnoid cyst for the treatment of presyrinx myelopathy--case report

A 32-year-old man presented with an arachnoid cyst of the posterior fossa manifesting as cervical syringomyelic myelopathy. Magnetic resonance (MR) imaging demonstrated edematous enlargement and T2 prolongation of the cervical spinal cord, indicating a "presyrinx" state. MR imaging showed the inferior wall of the cyst, which disturbed cerebrospinal fluid (CSF) pulsatile movement between the intraspinal and intracranial subarachnoid spaces. The cyst wall was fenestrated with a neuroendoscope. The presyrinx state and the CSF movement improved. Posterior fossa arachnoid cyst, as well as Chiari malformation, can cause CSF flow disturbance at the craniocervical junction and syringomyelia. Endoscopic fenestration is less invasive than foramen magnum decompression and should be the procedure of choice.     

Unraveling the riddle of syringomyelia

The pathophysiology of syringomyelia development is not fully understood. Current prevailing theories suggest that increased pulse pressure in the subarachnoid space forces cerebrospinal fluid (CSF) through the spinal cord into the syrinx. It is generally accepted that the syrinx consists of CSF. The here-proposed intramedullary pulse pressure theory instead suggests that syringomyelia is caused by increased pulse pressure in the spinal cord and that the syrinx consists of extracellular fluid. A new principle is introduced implying that the distending force in the production of syringomyelia is a relative increase in pulse pressure in the spinal cord compared to that in the nearby subarachnoid space. The formation of a syrinx then occurs by the accumulation of extracellular fluid in the distended cord. A previously unrecognized mechanism for syrinx formation, the Bernoulli theorem, is also described. The Bernoulli theorem or the Venturi effect states that the regional increase in fluid velocity in a narrowed flow channel decreases fluid pressure. In Chiari I malformations, the systolic CSF pulse pressure and downward motion of the cerebellar tonsils are significantly increased. This leads to increased spinal CSF velocities and, as a consequence of the Bernoulli theorem, decreased fluid pressure in narrow regions of the spinal CSF pathways. The resulting relatively low CSF pressure in the narrowed CSF pathway causes a suction effect on the spinal cord that distends the cord during each systole. Syringomyelia develops by the accumulation of extracellular fluid in the distended cord. In posttraumatic syringomyelia, the downwards directed systolic CSF pulse pressure is transmitted and reflected into the spinal cord below and above the traumatic subarachnoid blockage, respectively. The ensuing increase in intramedullary pulse pressure distends the spinal cord and causes syringomyelia on both sides of the blockage. The here-proposed concept has the potential to unravel the riddle of syringomyelia and affords explanations to previously unanswered clinical and theoretical problems with syringomyelia. It also explains why syringomyelia associated with Chiari I malformations may develop in any part of the spinal cord including the medullary conus. Syringomyelia thus preferentially develops where the systolic CSF flow causes a suction effect on the spinal cord, i.e., at or immediately caudal to physiological or pathological encroachments of the spinal subarachnoid space.     

Spontaneous resolution of syringomyelia without Chiari malformation

A 30-year-old woman presented with a cervical syrinx manifesting as hemihypesthesia. Neuroimaging found no evidence of Chiari malformation or tight cisterna magna. Serial magnetic resonance imaging studies over a 6-year period demonstrated spontaneous and complete resolution of the syrinx accompanied by an asymptomatic clinical course. The natural history of syringomyelia is highly unpredictable. The outcome of surgical treatment for patients with syringomyelia is not always satisfactory, so the indications for surgery are controversial. Spontaneous resolution of syringomyelia unrelated with foramen magnum lesion has various causes. Close follow up of the patient is necessary to monitor for recurrence.     

Pathogenesis of syringomyelia associated with Chiari type 1 malformation: review of evidences and proposal of a new hypothesis

The exact pathogenesis of syringomyelia associated with Chiari type 1 malformation is unknown, although a number of authors have reported their theories of syrinx formation. The purpose of this review is to understand evidences based on the known theories and to create a new hypothesis of the pathogenesis. We critically review the literatures on clinicopathological, radiological, and clinical features of this disorder. The previously proposed theories mainly focused on the driven mechanisms of the cerebrospinal fluid (CSF) into the spinal cord. They did not fully explain radiological features or effects of surgical treatment such as shunting procedures. Common findings of the syrinx in clinicopathological studies were the communication with the central canal and extracanalicular extension to the posterior gray matter. Most of the magnetic resonance imaging studies demonstrated blockade and alternated CSF dynamics at the foramen magnum, but failed to show direct communication of the syrinx with the CSF spaces. Pressure studies revealed almost identical intrasyrinx pressure to the subarachnoid space and decreased compliance of the spinal CSF space. Recent imaging studies suggest that the extracellular fluid accumulation may play an important role. The review of evidences promotes a new hypothesis of syrinx formation. Decreased absorption mechanisms of the extracellular fluid may underlie the pathogenesis of syringomyelia. Reduced compliance of the posterior spinal veins associated with the decreased compliance of the spinal subarachnoid space will result in disturbed absorption of the extracellular fluid through the intramedullary venous channels and formation of syringomyelia.     

Symptomatic Chiari malformation in adults: a new classification based on magnetic resonance imaging with clinical and prognostic significance

Thirty-five consecutive adults with Chiari malformation and progressive symptoms underwent surgical treatment at a single institution over a 3-year period. All patients underwent magnetic resonance imaging scan before and after surgery. Images of the craniovertebral junction confirmed tonsillar herniation in all cases and allowed the definition of two anatomically distinct categories of the Chiari malformation in this age group. Twenty of the 35 patients had concomitant syringomyelia and were classified as Type A. The remaining 15 patients had evidence of frank herniation of the brain stem below the foramen magnum without evidence of syringomyelia and were labeled Type B. Type A patients had a predominant central cord symptomatology; Type B patients exhibited signs and symptoms of brain stem or cerebellar compression. The principal surgical procedure consisted of decompression of the foramen magnum, opening of the fourth ventricular outlet, and plugging of the obex. Significant improvement in preoperative symptoms and signs was observed in 9 of the 20 patients (45%) with syringomyelia (Type A), as compared to 13 of the 15 patients (87%) without syringomyelia (Type B). Postoperative reduction in syrinx volume was observed in 11 of the 20 patients with syringomyelia, including all 9 patients with excellent results. Magnetic resonance imaging has allowed a classification of the adult Chiari malformation in adults based on objective anatomic criteria, with clinical and prognostic relevance. The presence of syringomyelia implies a less favorable response to surgical intervention.     

Laparoscopic cholecystectomy in a morbidly obese patient with Chiari I malformation and craniocervical anomalies

Chiari I malformation is the downward herniation of cerebellar tonsils through the foramen magnum, and is frequently associated with craniocervical anomalies. Laparoscopic surgery can cause an increase in intracranial pressure due to the obstruction of the foramen magnum. The successful administration of general anesthesia in a 50-year-old, morbidly obese woman with a difficult airway, scheduled for laparoscopic cholecystectomy, who was incidentally diagnosed with Chiari I malformation associated with craniocervical anomalies, is presented.     

Spontaneous resolution of syringomyelia: report of two cases and review of the literature

OBJECTIVE AND IMPORTANCE: The natural history of syringomyelia is highly unpredictable, and some patients experience improvement or stabilization without surgery. However, the mechanisms of the formation and spontaneous resolution of syringomyelia remain controversial. This report concerns two patients with syringomyelia who demonstrated spontaneous reductions in syrinx size, accompanied by symptomatic improvement. CLINICAL PRESENTATION: One patient was a 10-year-old girl with syringomyelia associated with a tight cisterna magna and basilar impression, who demonstrated a spontaneous decrease in syrinx size, accompanied by symptomatic improvement, in 22 months. The other patient was a 39-year-old man with syringomyelia associated with a Chiari I malformation, who demonstrated a spontaneous reduction in syrinx size and neurological improvement, accompanied by elevation of the cerebellar tonsils, 6 months after diagnosis. INTERVENTION: The patients were monitored. CONCLUSION: The mechanisms of spontaneous resolution of syringomyelia, as well as the factors leading to the cerebrospinal fluid flow disturbances that cause syringomyelia, may vary. Resolution of foramen magnum lesion-related syringomyelia may be the result of spontaneous correction of the abnormal cerebrospinal fluid flow, as observed in our cases, or of cavity fluid drainage into the spinal arachnoid space because of spinal cord fissuring.     

Asymptomatic Chiari Type I malformations identified on magnetic resonance imaging

OBJECT: Chiari Type I malformation (CMI) is a congenital disorder recognized by caudal displacement of the cerebellar tonsils through the foramen magnum and into the cervical canal. Frequently, associated findings include abnormalities of nearby bony and neural elements as well as syringomyelia. Cerebellar tonsillar ectopia is generally considered pathological when greater than 5 mm below the foramen magnum. However, asymptomatic tonsillar ectopia is an increasingly recognized phenomenon, the significance of which is poorly understood. METHODS: The authors retrospectively reviewed the records of all brain magnetic resonance (MR) images obtained at our hospital over a 43-month period in an attempt to ascertain the relative prevalence and MR imaging characteristics of asymptomatic CMIs. Of 22,591 patients who underwent MR imaging of the head and cervical spine, 175 were found to have CMIs with tonsillar herniation extending more than 5 mm below the foramen magnum. Of these, 25 (14%) were found to be clinically asymptomatic. The average extent of ectopia in this population was 11.4 +/- 4.86 mm, and was significantly associated with a smaller cisterna magna. Syringomyelia and osseous anomalies were found in only one asymptomatic patient. CONCLUSIONS: The authors suggest that the isolated finding of tonsillar herniation is of limited prognostic utility and must be considered in the context of all available clinical and radiographic data. Strategies for treating patients with asymptomatic CMIs are discussed.     

Management of syringomyelia associated with Chiari malformation: comparative study of syrinx size and symptoms by magnetic resonance imaging

The authors reviewed the postoperative alteration of symptoms and syrinx size by magnetic resonance imaging (MRI) in 14 consecutive patients with syringomyelia associated with Chiari malformation. The patients were treated according to our treatment regimen and were divided into five groups according to operative modalities: (1) only foramen magnum decompression (D) for small syrinx; (2) D with ventriculoperitoneal (VP) shunt for small syrinx with hydrocephalus; (3) D with syringosubarachnoid (SS) shunt or (4) D with syringoperitoneal (SP) shunt for large syrinx; and (5) only VP shunt for syrinx with hydrocephalus and atlantoaxial dislocation, respectively. From the preoperative and postoperative sagittal MR images, the areas of the spinal cord and syrinx were measured by a digitizer and the syringo-cord (S-C) ratio was calculated. Out of 14 patients, 12 showed a reduction of syrinx size and a stabilization or improvement of symptoms after surgery. In the other two patients, the syrinx size did not change and their symptoms worsened. Magnetic resonance imaging follow-up showed that foramen magnum decompression without shunt is effective for patients with a small syrinx below 35% of the S-C ratio, and foramen magnum decompression with shunt was effective for patients with a large syrinx over 35% of the S-C ratio, but there was no significant difference between the SS and SP shunt group.     

Surgical management of syringomyelia–Chiari complex

Great variety exists in the indications and techniques recommended for the surgical treatment of syringomyelia–Chiari complex. More recently, magnetic resonance (MR) imaging has increased the frequency of diagnosis of this pathology and offered a unique opportunity to visualize cavities inside the spinal cord as well as their relationship to the cranio-cervical junction. This report presents 18 consecutive adult symptomatic syringomyelia patients with Chiari malformation who underwent foramen magnum decompression and syringosubarachnoid shunting. The principal indication for the surgery was significant progressive neurological deterioration. All patients underwent preoperative and postoperative MRI scans and were studied clinically and radiologically to assess the changes in the syrinx and their neurological picture after surgical intervention. All patients have been followed up for at least 36 months. No operative mortality was encountered; 88.9% of the patients showed improvement of neurological deficits together with radiological improvement and 11.1% of them revealed collapse of the syrinx cavity but no change in neurological status. None of the patients showed further deterioration of neurological function. The experience obtained from this study demonstrates that foramen magnum decompression to free the cerebro-spinal fluid (CSF) pathways combined with a syringosubarachnoid shunt performed at the same operation succeeds in effectively decompressing the syrinx cavity, and follow-up MR images reveal that this collapse is maintained. In view of these facts, we strongly recommend this technique, which seems to be the most rational surgical procedure in the treatment of syringomyelia– Chiari complex. Received: 11 October 1999 Revised: 29 February 2000 Accepted: 20 March 2000     

Remote cerebellar hemorrhage after foramen magnum decompression surgery for Chiari I malformation--case report

A 47-year-old woman underwent decompressive suboccipital craniectomy and C1 laminectomy with duroplasty in the prone position for Chiari malformation type I and syringomyelia. The arachnoid membrane was not injured. Intraoperative echography showed good enlargement of the subarachnoid space. No closed subcutaneous drain was used. The patient complained of repeated nausea and vomiting 3 hours after the operation, and computed tomography revealed remote cerebellar hemorrhage on postoperative day 1. The cerebellar hemorrhage was treated conservatively, and the symptoms continued only for 3 days after surgery. Dural opening with rapid loss of cerebrospinal fluid (CSF) has occurred in every reported case of remote cerebellar hemorrhage complicating intracranial and spinal procedures. Loss of CSF is the main pathogenesis of this condition. In our case, the most probable pathomechanism seems to involve stretching of the infratentorial cerebellar bridging veins due to cerebellar sagging because of dural opening in the prone position and drop in CSF pressure. Such a complication is rare but should be considered after foramen magnum decompression surgery if the patient shows unusual symptoms of repeated vomiting.     

Spinal cord edema preceding syringomyelia associated with Chiari I malformation--case report

A 38-year-old woman with Chiari I malformation presented with spinal cord edema preceding syringomyelia manifesting as a 5-month history of nuchal pain and numbness of the upper extremities. Magnetic resonance imaging showed spinal cord edema, a poorly defined syrinx at the C-2 to T-2 levels, and distorted cerebellar tonsils. Computed tomography revealed cerebrospinal fluid (CSF) density in the center of spinal cord edema, and positron emission tomography revealed no uptake of L-[methyl-11C]methionine, indicating a non-neoplastic lesion. Craniocervical decompression achieved excellent clinical and neuroradiological outcomes. The success of surgical treatment supports the theory that patients with Chiari I malformation have increased transmural flow of CSF, causing spinal cord edema that progresses to syringomyelia. Early treatment of patients with spinal cord edema is indicated to prevent permanent spinal cord injury due to progressive syringomyelia.     

Chiari malformation (type I) associated with bilateral abducens nerve palsy: case report

There are still many questions concerning the pathology and therapeutic strategy for Chiari malformation. We recently encountered a case of Chiari malformation associated with only bilateral abducens nerve palsy which was successfully treated by foramen magnum decompression. The pathology and mechanisms of Chiari malformation (type I) were evaluated in this case. The patient was a 12-year-old girl who had visited our institute 1 month previously complaining of diplopia. She had no particular past or family history and her general appearance was also normal. Bilateral abducens nerve palsy was the only neurological deficit. Her cerebrospinal pressure was 9 cm H2O. Neuroradiological findings revealed basilar impression, C4-6 syringomyelia and Chiari malformation (type I), but no hydrocephalus or meningocele. Foramen magnum decompression with lateral extension, upper cervical laminectomy and open duraplasty were performed. The position of both eyes recovered fully shortly after surgery, and diplopia occurred only when the patient looked sideways. Eye movements also returned completely to normal 3 months after surgery. MRI showed no syringomyelia 4 months after surgery, the upward shift of the pendulous portion of the cerebellar tonsil, and the expansion of the subarachnoidal space of the pons-oblongata junction. In conclusion, it was thought that the mechanism of bilateral abducens nerve palsy in this case was due to the strangulation and the downward traction of the pons-oblongata junction. The nerve was relieved from this traction by foramen magnum decompression.     

Decompression of the spinal subarachnoid space as a solution for syringomyelia without Chiari malformation

STUDY DESIGN: Review and analysis of seven cases of syringomyelia treated surgically. OBJECTIVE: To demonstrate the beneficial role of decompressive surgery for the altered cerebrospinal fluid (CSF) flow dynamics in syringomyelia not associated with Chiari I malformation. A comparison between the pre- and post-operative syrinx size and CSF flow in the subarachnoid space was made using cine-mode magnetic resonance imaging (cine-MRI) and then correlated with clinical improvement. SETTING: University Hospital, Seoul, Korea. METHODS: Conventional spinal MRI and cine-MRI were performed in the region of CSF flow obstruction preoperatively in seven patients with syringomyelia not associated with Chiari I malformation. The group consisted of one case of syrinx with post-traumatic compression fracture, one case of post-traumatic arachnoiditis, two cases of holocord syrinx associated with hydrocephalus without Chiari malformation, one case of syrinx with post-traumatic pseudomeningeal cyst, one case of post-laminectomy kyphosis-associated syringomyelia and one case of post-tuberculous arachnoiditis syringomyelia. Based on the preoperative cine-MRI, the types of surgery appropriate to correct the CSF flow obstruction were chosen: decompressive laminectomy-adhesiolysis and augmentation duraplasty in arachnoiditis cases, ventriculoperitoneal shunt for hydrocephalus, cyst extirpation in pseudomeningeal cyst and both anterior and posterior decompression-fusion in the case of post-laminectomy kyphosis. A syrinx-draining shunt operation was performed in three cases; where the syringomyelia was associated with post-traumatic compression fracture refractory to a previous decompression, where hydrocephalus was present in which the decompression by ventriculoperitoneal shunt was insufficient and where post-traumatic arachnoiditis was present in which the decompression was impossible due to diffuse adhesion. Change in syrinx size was evaluated with post-operative MRI in all seven cases and restoration of flow dynamics was evaluated with cine-MRI in three of the cases, two patients with clinical improvement and one patient with no change of clinical status, respectively. RESULTS: Four out of seven patients showed symptomatic improvement after each decompressive operation. In the remaining three cases, reconstruction of the spinal subarachnoid space was not possible due to diffuse adhesion or was not the main problem as in the patient with syrinx associated with hydrocephalus who had to undergo a shunt operation. One of these three patients showed clinical improvement after undergoing syringosubarachnoid shunt. A decrease of syrinx size was observed in only two out of the five patients who showed clinical improvement after treatment. Of these five patients, two patients underwent post-operative cine-MRI and the restoration of normal CSF flow dynamics was noted in both patients. Of the remaining two patients, one underwent post-operative cine-MRI and there was no change in the CSF flow dynamics evident. CONCLUSION: These results suggest that the restoration of CSF flow dynamics between the syrinx and the subarachnoid space by decompressive operation is more effective than simple drainage of the syrinx cavity itself in the treatment of syringomyelia without Chiari malformation.     

Factors contributing to improvement of syringomyelia after foramen magnum decompression for Chiari type I malformation

Background

Although various surgical approaches have been proposed for treating syringomyelia associated with Chiari type I malformation, a standard method has yet to be established. we prospectively investigated the results of our surgical method: foramen magnum decompression combined with C1 laminectomy and excision of the outer layer of the dura mater.

Methods

Twenty patients underwent surgery between 2000 and 2010 at our hospital. After surgery, the size of the syrinx decreased in 11 patients (decreased group) but remained unchanged in nine patients (unchanged group). The following parameters were compared: age at the time of surgery, duration of morbidity, improvement of preoperative symptoms, morphological type and length of the syrinx, presence or absence of scoliosis, cervical alignment, basal and clivo-axial angles, and postoperative subarachnoid space at the foramen magnum level.

Results

Preoperative symptoms improved in all patients in the decreased group but in only one patient in the unchanged group. The average duration of morbidity was significantly shorter in the decreased group. Morphological examination revealed that the size of all central-type syrinxes decreased after surgery, whereas in all cases of deviated-type syrinx, size was unchanged. The average length of preoperative syrinx was significantly shorter in the decreased group. The postoperative subarachnoid space at the foramen magnum was enlarged in the entire decreased group, whereas residual narrowing of the space was observed in 44 % of patients in the unchanged group. No significant intergroup differences were observed in the other factors.

Conclusions

In patients with syringomyelia, a longer and deviated type of syrinx, a longer duration of morbidity, and postoperative residual narrowing of the subarachnoid space are associated with a poor prognosis after the surgical procedure. The pathogenesis of syringomyelia is inconsistent, and the choice of surgical technique for each pathological condition is important.     

Transverse Microincisions of the Outer Layer of the Dura mater Combined with Foramen Magnum Decompression as Treatment for Syringomyelia with Chiari I Malformation

Summary Numerous surgical procedures have been proposed for treatment of syringomyelia associated with Chiari I malformation, but the optimal treatment has not yet been uniformly standardised. The main aim of the surgical treatment of syringomyelia/Chiari I complex is directed toward restoration of physiological cerebrospinal fluid dynamic at the craniovertebral junction. We report the surgical results of eight patients, affected by syringomyelia and Chiari I malformation, age range from 18 to 62 years, treated by bony foramen magnum decompression combined with transverse microincisions of the outer layer of the dura mater. In an average postoperative follow-up period of two years neurological symptoms and signs improved in seven patients. Postoperative Magnetic Resonance showed a decrease in size of the syrinx in seven patients. These results suggest that foramen magnum decompression combined with transverse microincisions of the outer layer of the dura 1) is an effective and safe treatment option for syringomyelia and Chiari I malformation, 2) corrects the circulatory disturbances of cerebrospinal fluid dynamic, 3) leads to a decrease in size of the syrinx and to a significant improvement in neurological signs and symptoms, 4) avoids complications of intradural approaches and syringosubarachnoid shunting.