Thecoperitoneal shunt for syringomyelia: report of three cases

Treatment of Holocord Syringomyelia-Chiari Complex by Posterior Fossa Decompression and a Syringosubarachnoid Shunt in a Single-Stage Single Approach

BACKGROUND

Posterior fossa decompression with expansive duraplasty is the first-line surgical approach for the treatment of symptomatic syringomyelia associated with Chiari malformation. Despite good decompression, the clinical failure rate is reported to be up to 26%. A syringosubarachnoid (S-S) shunt may be used as a secondary option.

METHODS

In this paper we describe a single-institution experience of three cases of holocord syringomyelia-Chiari complex treated with foramen magnum decompression, expansive duraplasty and an S-S shunt carried out in a single-stage single approach. Following a standard suboccipital craniectomy, patients were submitted to syrinx fenestration and simultaneous insertion of an S-S shunt through a 1-mm posterior midline myelotomy at the C2 level prior to expansive dural reconstruction.

RESULTS

Postoperative imaging showed immediate reduction of the holocord cavities. Preoperative neurological deficits rapidly improved significantly and were stabilized at follow-up.

CONCLUSION

In our experience the positioning of the shunt catheter at a high level of the spinal cord (C2) did not add a significant risk of morbidity and obviated the need for a second operation and/or a separate incision in cases of clinical failure. This technique avoided the risk associated with a second surgery and its morbidity, and allowed prompt clinical recovery.

Pathophysiology of primary spinal syringomyelia

OBJECT

The pathogenesis of syringomyelia in patients with an associated spinal lesion is incompletely understood. The authors hypothesized that in primary spinal syringomyelia, a subarachnoid block effectively shortens the length of the spinal subarachnoid space (SAS), reducing compliance and the ability of the spinal theca to dampen the subarachnoid CSF pressure waves produced by brain expansion during cardiac systole. This creates exaggerated spinal subarachnoid pressure waves during every heartbeat that act on the spinal cord above the block to drive CSF into the spinal cord and create a syrinx. After a syrinx is formed, enlarged subarachnoid pressure waves compress the external surface of the spinal cord, propel the syrinx fluid, and promote syrinx progression.

METHODS

To elucidate the pathophysiology, the authors prospectively studied 36 adult patients with spinal lesions obstructing the spinal SAS. Testing before surgery included clinical examination; evaluation of anatomy on T1-weighted MRI; measurement of lumbar and cervical subarachnoid mean and pulse pressures at rest, during Valsalva maneuver, during jugular compression, and after removal of CSF (CSF compliance measurement); and evaluation with CT myelography. During surgery, pressure measurements from the SAS above the level of the lesion and the lumbar intrathecal space below the lesion were obtained, and cardiac-gated ultrasonography was performed. One week after surgery, CT myelography was repeated. Three months after surgery, clinical examination, T1-weighted MRI, and CSF pressure recordings (cervical and lumbar) were repeated. Clinical examination and MRI studies were repeated annually thereafter. Findings in patients were compared with those obtained in a group of 18 healthy individuals who had already undergone T1-weighted MRI, cine MRI, and cervical and lumbar subarachnoid pressure testing.

RESULTS

In syringomyelia patients compared with healthy volunteers, cervical subarachnoid pulse pressure was increased (2.7 ± 1.2 vs 1.6 ± 0.6 mm Hg, respectively; p = 0.004), pressure transmission to the thecal sac below the block was reduced, and spinal CSF compliance was decreased. Intraoperative ultrasonography confirmed that pulse pressure waves compressed the outer surface of the spinal cord superior to regions of obstruction of the subarachnoid space.

CONCLUSIONS

These findings are consistent with the theory that a spinal subarachnoid block increases spinal subarachnoid pulse pressure above the block, producing a pressure differential across the obstructed segment of the SAS, which results in syrinx formation and progression. These findings are similar to the results of the authors' previous studies that examined the pathophysiology of syringomyelia associated with obstruction of the SAS at the foramen magnum in the Chiari Type I malformation and indicate that a common mechanism, rather than different, separate mechanisms, underlies syrinx formation in these two entities. Clinical trial registration no.: NCT00011245.

The role of lumboperitoneal shunts in the treatment of syringomyelia

OBJECT The role of thecoperitoneal shunts in the management of syringomyelia is not well defined. In this study, the authors analyze the outcome of lumboperitoneal shunt procedures carried out to treat syringomyelia in their institution. METHODS The authors retrospectively reviewed the medical records of 19 patients who underwent lumboperitoneal shunt procedures for syringomyelia. RESULTS The mean follow-up duration was 25 months (range 3-51 months). Of 16 cases followed up, only 5 patients reported clinical improvement in their preoperative symptoms, but of these, 2 had clear radiological evidence of improvement. Three of 6 patients with syringomyelia due to spinal arachnoiditis improved. CONCLUSIONS Lumboperitoneal shunts may lead to useful improvement in the symptoms of a patient with syringomyelia while avoiding the risk of neurological deterioration inherent in myelotomies required for syrinx shunting procedures.

Thecal shunt placement for treatment of obstructive primary syringomyelia

OBJECT

The most commonly reported treatment of primary syringomyelia has been laminectomy with duraplasty or direct shunting from the syrinx cavity. Diversion of cerebrospinal fluid (CSF) from the spinal subarachnoid space to peritoneal, atrial, or pleural cavities has been described previously in only a few case reports. Shunting of the CSF from the subarachnoid space rostral to the level of myelographic blockage may reduce the filling force of the syrinx cavity and avoids myelotomy and manipulation of the spinal cord parenchyma. The authors report on 7 patients who underwent thecal shunt placement for primary spinal syringomyelia.

METHODS

This study is a retrospective review of a consecutive series. The authors reviewed the medical records and neuroimaging studies of 7 adult patients with posttraumatic, postsurgical, or postinflammatory syringomyelia treated with thecoperitoneal, thecopleural, or thecoatrial shunt placement at the University of California Los Angeles Medical Center. Myelographic evidence of partial or complete CSF flow obstruction was confirmed in the majority of patients. The mean duration of follow-up was 33 months (range 6-104 months).

RESULTS

Six (86%) of 7 patients showed signs of clinical improvement, whereas 1 remained with stable clinical symptoms. Of the 6 patients with available postoperative imaging, each demonstrated a reduction in syrinx size. Three patients (43%) had > or = 1 complication, including shunt-induced cerebellar tonsillar descent in 1 patient and infections in 2.

CONCLUSIONS

If laminectomy with duraplasty is not possible for the treatment of primary syringomyelia, placement of a thecoperitoneal shunt (or thecal shunt to another extrathecal cavity) should be considered. Although complications occurred in 3 of 7 patients, the complication rate was outweighed by a relatively high symptomatic and imaging improvement rate.

Surgical outcomes in adult patients with syringomyelia associated with Chiari malformation Type I: the relationship between scoliosis and neurological findings

Object

The clinical characteristics of pediatric scoliosis associated with syringomyelia have been reported in previous studies, but scoliosis associated with syringomyelia in adults is rarely treated, and there is a paucity of detailed studies. In the present study of adult syringomyelia associated with Chiari malformation Type I, the authors investigated the relationships among the syrinx, scoliosis, and neurological data.

Methods

The population was composed of 27 patients (≥ 20 years of age) who underwent foramen magnum decompression for the treatment of syringomyelia. The patients were divided into two groups: those with scoliosis of 10° or more (Group A) and those without scoliosis (Group B). The authors assessed the length of the syrinx, duration of morbidity, and clinical status before and after surgery based on the Japanese Orthopaedic Association (JOA) Scale.

There were 15 cases in Group A and 12 in Group B. The mean length of the syrinx was 12.8 vertebral bodies (VBs) in Group A and 7.2 VBs in Group B. The mean duration of morbidity was 14.2 years in Group A and 6.8 years in Group B. The mean preoperative JOA score was 10.1 in Group A and 14.4 in Group B, whereas the mean postoperative JOA scores were 11.9 and 15.8, respectively. There were significant differences between Groups A and B in length of the syrinx, duration of morbidity, and pre- and postoperative JOA scores.

Conclusions

In patients with syringomyelia and scoliosis the syringes spanned a greater number of VBs, the duration of morbidity was greater, neurological dysfunction was more severe, and surgical results were poorer. Scoliosis could be a predicting factor of the prognosis in patients with syringomyelia and Chiari malformation Type I.

Chiari I malformation associated with atlanto-axial dislocation: focussing on the anterior cervico-medullary compression

BACKGROUND

Chiari I malformation with atlantoaxial dislocation may cause both posterior and anterior cervicomedullary compression. We studied the clinicoradiological features and surgical outcome in patients having Chiari I malformation with atlantoaxial dislocation.

METHOD

Thirty-nine patients with Chiari I malformation with atlanto-axial dislocation underwent preoperative and follow-up neurological status assessment. In Chiari I malformation with reducible atlanto-axial dislocation (n = 11), a direct posterior stabilization was done. In Chiari I malformation with irreducible atlanto-axial dislocation (n = 28), a single stage transoral decompression with posterior stabilization and/or posterior decompression and duraplasty were done in 18 patients. In 10 patients, only posterior decompression and/or posterior stabilization was performed. Seven among the latter patients subsequently deteriorated and required transoral decompression. Comparison of mean neurological status scores of patients with Chiari I malformation with irreducible atlanto-axial dislocation who underwent single stage transoral decompression with posterior stabilization versus the posterior procedure alone was done using T-test and proportional significance also calculated.

FINDINGS

Patients with Chiari I malformation with atlanto-axial dislocation have a high incidence of long tract signs and sphincteric disturbances with a decrease in the mean foramen magnum diameter. The mean neurological status scores of patients with Chiari I malformation with irreducible atlanto-axial dislocation who underwent single stage transoral decompression with posterior stabilization were significantly better than those patients who underwent the posterior procedure alone. The latter patients also showed significant clinical improvement following transoral decompression. In the presence of Chiari I malformation with reducible atlanto-axial dislocation, reduction and stabilization of atlanto-axial dislocation resulted in neurological improvement. The follow up neurological status scores of these patients improved after surgical intervention even in the presence of poor preoperative grades.

CONCLUSIONS

Patients with Chiari I malformation should be investigated for the presence of atlanto-axial dislocation. In case atlantoaxial dislocation coexists, priority must be given to relieving anterior cervicomedullary compression.

Primary spinal syringomyelia. Invited submission from the joint section meeting on disorders of the spine and peripheral nerves, March 2005

In the present review the author describes the different types of syringomyelia that originate from abnormalities at the level of the spinal cord rather than at the craniovertebral junction. These include posttraumatic and postinflammatory syringomyelia, as well as syringomyelia associated with arachnoid cysts and spinal cord tumors. The diagnosis and the principles of managing these lesions are discussed, notably resection of the entity restricting cerebrospinal fluid flow. Placement of a shunt into the syrinx cavity is reserved for patients in whom other procedures have failed or who are not candidates for other procedures.

Subarachnoid pressure—dependent change in syrinx size in a patient with syringomyelia associated with adhesive arachnoiditis

✓ The pathophysiology of syringomyelia is still not well understood. Current prevailing theories involve the assumption that cerebrospinal fluid (CSF) flows into the syrinx from the subarachnoid space through the perivascular space of Virchow—Robin. Reported here is the case of a patient with syringomyelia in which this course is clearly contradicted.

This patient with a holocord syrinx associated with adhesive arachnoiditis was treated 3 years previously with insertion of a subarachnoid—peritoneal shunt and had recently experienced worsening myelopathy. On surgical exploration, the shunt system was functioning normally. The medium-pressure shunt valve was replaced with an adjustable valve with a higher closing pressure setting, thus increasing the CSF pressure in the subarachnoid space. Contrary to prevailing theories, this procedure markedly reduced the size of the syrinx.

This case provides direct evidence that the syrinx size is inversely related to subarachnoid CSF pressure and supports the hypothesis that the pressure gradient across the spinal cord parenchyma is the force that generates syringes in syringomyelia.

Surgical experience of syringomyelia with reference to the findings of magnetic resonance imaging

We present our surgical experience of 20 patients with syringomyelia, who were divided into two groups based on the findings of magnetic resonance (MR) imaging: a "non-visible cisterna magna" group, in which MR imaging did not reveal cerebrospinal fluid (CSF) in the cisterna magna, and a "visible cisterna magna" group. Patients with non-visible cisterna magna were associated with Chiari malformation (14 patients) or tight cisterna magna (4 patients) and underwent craniocervical decompression. Intradural exploration was performed when CSF movement in the cisterna magna or CSF outflow from the fourth ventricle appeared to be insufficient. It is important to confirm CSF outflow from the foramen of Magendie. Patients with visible cisterna magna were associated with tuberculous meningitis (2 patients) and underwent shunting procedures. Postoperatively, improvement in symptoms and a reduction in syrinx size were demonstrated in all patients except one. Two patients experienced recurrence of symptoms and syrinx dilatation.

Adult scoliosis in syringomyelia associated with Chiari I malformation

STUDY DESIGN

In adult syringomyelia associated with Chiari I malformation, the spinal deformity, the configuration of cerebellar tonsillar descent, the configuration of syrinx, and the clinical evaluation before and after surgery were investigated.

OBJECTIVES

To investigate the characteristics of the scoliosis in syringomyelia associated with Chiari I malformation.

SUMMARY OF BACKGROUND DATA

In previous studies, the clinical characteristics of pediatric scoliosis associated with syringomyelia have been reported.

METHODS

In this study, 42 patients with syringomyelia were treated. All the patients were 20 years of age or older. They were divided into three groups: Group 1 comprising those without scoliosis, Group 2 composed of those with scoliosis of 10 degrees or more but less than 20 degrees, and Group 3 consisting of those with scoliosis of 20 degrees or more. Investigations conducted with the three groups included determining the curve patterns of scoliosis, the degree of thoracic kyphosis, the configuration of cerebellar tonsillar descent, the configuration of syrinx, the morbidity period, and the clinical evaluation before and after surgery.

RESULTS

There were 12 patients in Group 1, 21 patients in Group 2, and 9 patients in Group 3. The concomitant rate of adult syringomyelia with scoliosis was 71.4%. As scoliosis advanced, the kyphotic angle also increased. The concordance in laterality between the cerebellar tonsil and curve convex was 70%. Findings showed that the more advanced the scoliosis was, the more aggravated the neurologic symptoms were, and the poorer the surgical outcomes tended to be.

CONCLUSIONS

In adult syringomyelia with scoliosis, the morbidity period is long, the syrinx is long, the neurologic symptoms are aggravated, and the surgical outcomes tend to be poor.

Syringosubarachnoid shunt for syringomyelia associated with Chiari I malformation

OBJECT

The authors describe the surgical procedures for placing syringosubarachnoid shunts and the results of surgery, as well as the prevention of shunt malfunction.

METHODS

The series consisted of 59 patients with syringomyelia associated with Chiari I malformation in whom syringosubarachnoid shunts were placed. Their ages ranged from 4 to 62 years (median 28 years). The follow-up period ranged from 13 to 219 months. The authors principally implanted the shunts in patients with large-sized syringes. Neurological improvement was satisfactory, and postoperative magnetic resonance imaging demonstrated that the syringes had resolved or decreased in size in all patients. Reoperation was necessary in 10 patients who were treated before 1993.

CONCLUSIONS

To prevent shunt malfunction, both dorsal root entry zone myelotomy and placement of the syringosubarachnoid shunt tube into the ventral subarachnoid space are useful.

Successful neuroendoscopic third ventriculostomy for hydrocephalus and syringomyelia associated with fourth ventricle outlet obstruction. Case report

The authors report the use of neuroendoscopic third ventriculostomy to treat successfully both hydrocephalus and syringomyelia associated with fourth ventricle outlet obstruction. A 27-year-old woman presented with dizziness, headache, and nausea. Magnetic resonance (MR) imaging demonstrated dilation of all ventricles, downward displacement of the third ventricular floor, obliteration of the retrocerebellar cerebrospinal fluid (CSF) space, funnellike enlargement of the entrance of the central canal in the fourth ventricle, and syringomyelia involving mainly the cervical spinal cord. Cine-MR imaging indicated patency of the aqueduct and an absent CSF flow signal in the area of the cistema magna, which indicated obstruction of the outlets of the fourth ventricle. Although results of radioisotope cisternography indicated failure of CSF absorption, neuroendoscopic third ventriculostomy completely resolved all symptoms as well as the ventricular and spinal cord abnormalities evident on MR images. Neuroendoscopic third ventriculostomy is an important option for treating hydrocephalus in patients with fourth ventricle outlet obstruction.

Primary spinal syringomyelia: a personal perspective

In this paper the author summarizes currently available surgical approaches to spinal syringomyelia that is unrelated to Chiari I malformation or hindbrain descent. Primary spinal syringomyelia is most comonly associated with spinal trauma but is also encountered as a sequela to intradural inflammatory processes (infections or chemical), as a delayed response to surgical procedures, and in association with intra- and extradural neoplasms as well as disc protrusions. The advantages of placing a shunt are its technical simplicity and immediate reduction of syrinx size; its major disadvantages are the high rate of failure observed in long-term follow up and the difficulty in applying this technique in septated cysts. Expansion of the subarachnoid space with resection of scars has better long-term results. Patients in whom a syrinx cavity has caused a kyphotic spinal deformity may need to undergo a procedure in which the kyphotic deformity is corrected to expand the subarachnoid space. Cyst obliteration is an experimental approach that cannot be evaluated at the present time.

Mechanisms underlying the formation and enlargement of noncommunicating syringomyelia: experimental studies

The pathogenesis of noncommunicating syringomyelia is unknown, and none of the existing theories adequately explains the production of cysts that occur in association with conditions other than Chiari malformation. The authors' hypothesis is that an arterial pulsation–driven perivascular flow of cerebrospinal fluid (CSF) is responsible for syrinx formation and enlargement. They investigated normal CSF flow patterns in 20 rats and five sheep by using the tracer horseradish peroxidase; the effect of reducing arterial pulse pressure was examined in four sheep by partially ligating the brachiocephalic trunk; CSF flow was examined in 78 rats with the intraparenchymal kaolin model of noncommunicating syringomyelia; and extracanalicular cysts were examined using the excitotoxic model in 38 rats.

In the normal animals there was a rapid flow of CSF from the spinal subarachnoid space into the spinal cord perivascular spaces and then into the central canal. This flow ceased when arterial pulsations were diminished. In animals with noncommunicating syringomyelia, there was rapid CSF flow into isolated and enlarged segments of central canal, even when these cysts were causing pressure damage to the surrounding spinal cord. Exitotoxic injury of the spinal cord caused the formation of extracanalicular cysts, and larger cysts were produced when this injury was combined with arachnoiditis, which impaired subarachnoid CSF flow. The results of these experiments support the hypothesis that arterial pulsation–driven perivascular fluid flow is responsible for syrinx formation and enlargement.

Reevaluation of syringosubarachnoid shunt for syringomyelia with Chiari malformation

OBJECTIVE

The purpose of this study was to evaluate the effectiveness of syringosubarachnoid (S-S) shunting for syringomyelia with Chiari malformation. The authors describe the technical methods of performing the S-S shunt and the clinical results, including shunt malfunction.

METHODS

Forty-nine patients underwent S-S shunting. These patients were divided into three groups according to differences in the surgical technique used. Group I patients underwent laminectomy plus midline myelotomy and had a shunt tube placed in the dorsal subarachnoid space. Group II patients underwent laminectomy plus dorsal root entry zone myelotomy and had a shunt tube placed in the dorsolateral subarachnoid space. Group III patients underwent hemilaminectomy plus dorsal root entry zone myelotomy and had a shunt tube placed in the ventrolateral subarachnoid space.

RESULTS

Clinical results were generally satisfactory, especially in terms of pain relief, in all three groups. However, 10 patients among Groups I and II required follow-up surgery because of shunt problems; no second surgery was necessary for any patient in Group III.

CONCLUSION

The S-S shunt was very effective in deflating the syrinx, and the clinical results were satisfactory. Therefore, even though foramen magnum decompression is a very effective treatment, S-S shunting should be reevaluated and not rejected; it should be considered as one of the major surgical options. To prevent the possibility of cord injury by myelotomy or shunt malfunction, the dorsal root entry zone should be selected as the myelotomy site, and the shunt tube should be inserted into the ventral subarachnoid space at the cervical level.

Pediatric syringomyelia with chiari malformation: its clinical characteristics and surgical outcomes

BACKGROUND

Most reports regarding pediatric syringomyelia have focused not only on Chiari malformation, but also on spinal dysraphism. However, the clinical characteristics of syringomyelia with spinal dysraphism are quite different from those of syringomyelia due to Chiari Type I malformation. The objectives of this study were to identify clinical characteristics of pediatric syringomyelia and to determine whether surgery prevents or corrects the scoliosis associated with syringomyelia.

METHODS

We reviewed the records of 16 pediatric patients with syringomyelia and Chiari Type I malformation. The patients' ages ranged from 3 to 15 years, with mean age of 9.8 years. None of the patients had spinal dysraphism.

RESULTS

Nystagmus was observed in 2 of the 16 patients, motor weakness in 8 patients, sensory disturbance in 10 patients, and scoliosis in 13 patients. As the initial surgical procedure, foramen magnum decompression (FMD) was performed in seven patients and syringo-subarachnoid (S-S) shunting in nine patients. The motor function improved in 7 of the 8 affected patients, and the sensory disturbance improved in 9 of the 10 affected patients. The magnetic resonance images obtained after the surgery revealed marked decrease of the syrinx size in all patients. Of the 13 patients with scoliosis, 5 showed improvement, 5 stabilization, and 3 deterioration.

CONCLUSIONS

Compared with adolescent and adult syringomyelia, pediatric syringomyelia shows a much lower incidence of sensory disturbance and pain, but quite a high incidence of scoliosis. Surgery is effective in improving or stabilizing scoliosis in these patients.

Surgical indication and results of foramen magnum decompression versus syringosubarachnoid shunting for syringomyelia associated with Chiari I malformation

Several surgical procedures have been used for the treatment of syringomyelia associated with Chiari I malformation at our institute. The purpose of this article is to evaluate the results of two major surgical procedures, foramen magnum decompression (FMD) and syringosubarachnoid (SS) shunting. The series consisted of 70 patients with syringomyelia associated with Chiari I malformation who were surgically treated. Their ages ranged from 3 to 59 years (median, 29.4 yr). FMD was performed on 33 patients, and SS shunting was performed on 37 patients. The follow-up period ranged from 6 months to 12.5 years, with a mean of 60 months. The clinical and radiological outcomes were analyzed comparing the two groups. We principally performed FMD in patients with symptoms of Chiari I malformation and/or a small syrinx. We prefer to use SS shunting in patients with large syringes. Postoperative magnetic resonance imaging demonstrated that the syrinx had collapsed or decreased in size in 94% of the patients who underwent FMD and in 100% of the patients who underwent SS shunting. Neurological improvements were observed in 82% and in 97% of the patients who underwent FMD and SS shunting, respectively. In particular, the relief of pain was more fully achieved after SS shunting than after FMD. The average time for the syrinx to collapse was 6.3 weeks after surgery in the FMD group and 1.8 weeks in the SS shunting group. These results indicate that clinical symptoms and radiological findings improved much more quickly in the SS shunting group than in the FMD group.(ABSTRACT TRUNCATED AT 250 WORDS)

The cystic spinal cord

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Thecoperitoneal shunt for post-traumatic syringomyelia

A case of post-traumatic syringomyelia developing two years after spinal cord injury is presented. The patient was treated with the placement of a thecoperitoneal shunt incorporating a low pressure valve. Response was excellent with restoration of neurological function and almost complete collapse of the cavity at one year follow up. The rationale of this form of treatment is discussed in the light of recent evidence concerning the pathogenesis of the condition.