Lumboperitoneal Shunt Insertion Research Articles

Laparoscopic-assisted lumboperitoneal shunt insertion with concomitant sleeve gastrectomy in obese patients with idiopathic intracranial hypertension: a retrospective comparative study with promising results

Laparoscopic-assisted lumboperitoneal shunt insertion with concomitant sleeve gastrectomy in obese patients with idiopathic intracranial hypertension: a retrospective comparative study with promising results

Incidence of radiculopathy following lumboperitoneal shunt placement without fluoroscopy for normal pressure hydrocephalus.

Spinal catheter insertion in lumboperitoneal shunt (LPS) surgery for normal pressure hydrocephalus (NPH) can result in radiculopathy due to mechanical irritation of the nerve roots of the cauda equina. Here, we analyzed the position of LPS shunts placed without portable fluoroscopy in 72 patients, a subset of whom developed postoperative radiculopathy. We retrospectively analyzed how frequently 72 consecutive NPH patients experienced radiculopathy following LPS catheter placement performed without intraoperative fluoroscopy. The rate of incorrect catheter placement was 15.3% (11/72 cases). We observed that is, downward placement in 6.9% (5/72 cases), hyperflexion in 6.9% (5/72 cases), and subcutaneous migration in 1.4% (1/72 cases) patients. One patient with initial correct LPS placement developed radicular pain 5-day postoperatively attributed to 1-cm of catheter movement; they recovered simply by utilizing oral analgesics for 1-month duration. LPS insertion without fluoroscopic guidance resulted in a 15.3% risk of spinal catheter displacement. We suggest, therefore, that intraoperative imaging guidance be utilized for the placement of LPS in patients with NPH and/or for other pathology to avoid the 15.3% risk of postoperative radiculopathy.

Bilateral sixth cranial nerve palsy following lumboperitoneal shunt

Lumboperitoneal (LP) shunt is considered as a unique procedure in neurosurgical practice. The over drainage of Cerebrospinal fluid (CSF) is considered a usual side effect of the procedure that usually manifests in the form of subdural collection, headache, or nausea and vomiting. However, cranial nerve palsy, particularly abducens nerve palsy, is a rare manifestation of CSF over drainage. We describe our experience with a patient that has developed bilateral sixth nerve palsy followed by LP shunt insertion, with resolution of the symptoms upon removal of the shunt. This shades the light on a rare but significant complication related to Lumboperitoneal (LP) shunt insertion that necessitate the modification in the hardware of valve or insertion technique to decrease the risk of CSF over the drainage.

Lumboperitoneal Shunt Combined With Ommaya Reservoir Enables Continued Intraventricular Chemotherapy for Leptomeningeal Metastasis With Increased Intracranial Pressure.

Intra-cerebrospinal fluid (CSF) chemotherapy for leptomeningeal metastasis (LM) can be delivered intraventricularly via an Ommaya reservoir. However, hydrocephalus associated with LM can interfere with chemotherapeutic drug distribution, and ventriculoperitoneal shunts can prevent drug distribution to the extra-ventricular CSF space. This study examined the feasibility of combining a lumboperitoneal (LP) shunt with an Ommaya reservoir to both control intracranial pressure and allow for intraventricular chemotherapy. We identified 16 patients with LM who received both an Ommaya reservoir and an LP shunt, either concurrently or sequentially, and subsequently received intraventricular chemotherapy. The feasibility of this combination for intraventricular chemotherapy was evaluated by assessing 1) the distribution of intraventricularly injected drugs in CSF samples collected 0, 6, and 12 h post-injection and 2) adverse events associated with the procedure and drug administration. Patients received a median of seven rounds (range 1-37) of intraventricular chemotherapy during a median follow-up period of 5.2 months after LP shunt insertion. Pharmacokinetic data were obtained from six patients. Baseline methotrexate (MTX) levels from Ommaya reservoirs varied from 339.9 µM to 1,523.5 µM. CSF sampled from LP shunt reservoirs revealed an elimination half-life (t1/2) of 2.63 h, and the mean ratio of MTX concentration at 12 h to that at baseline was 0.05±0.05, ensuring drug distribution from the ventricle to the spinal canal. Nine patients (56%) underwent revision surgery due to catheter migration, malfunction, or infection. Among these patients, CSF infections attributable to intraventricular chemotherapy (n=3) occurred, but no infections occurred in later cases after we began to employ a complete aseptic technique. LP shunt combined with Ommaya reservoir insertion is a feasible option for achieving both intracranial pressure control and the continuation of intraventricular chemotherapy in patients with LM.

Prophylactic lumboperitoneal shunt in cases of cerebral venous sinus thrombosis with papilledema

Background: Although the mainstay of cerebral venous sinus thrombosis treatment is medical, rarely surgical intervention is warranted. We aimed to determine the role of prophylactic lumbo-peritoneal (LP) shunt in cases of CVST with papilledema.Methods: This is a retrospective review of 70 cases of CVST managed between November 2019 to April 2020. Indications for surgical management included poor response to medical management and severe vision impairment.Results: The mean age of the patients included in the study was 39.44±4.76 years. The most common presenting complaint was headache (83%) and nausea/vomiting (69%). On examination, the common findings were papilledema (57%), blurred vision (31%), double vision (21%) and hemiparesis (11%). Two cases had sudden loss of vision, who underwent emergency LP shunt surgery. Of the 40 cases with papilledema, 8 had severe papilledema. Based on MRI venography, transverse sinus was involved in half of all patients, superior sagittal sinus was involved in 29% and 21% had both the sinuses involved, while 7% had cortical vein thrombosis. Anticoagulants was the first line of therapy for the patients. Papilledema was present in 40 cases, of which 10 showed complete resolution of symptoms, 15 cases had reduced severity of symptoms and symptoms persisted in rest of the 15 cases. The 10 cases who had complete resolution of symptoms included two patients who underwent LP shunt. There were no deaths.Conclusions: We recommend that a LP shunt insertion in a patient with severe papilledema with superior sagittal sinus thrombosis can prevent disease progress, preserve vision and facilitate re-canalisation.

Recurrent spontaneous CSF rhinorrhea: combined endo-nasal endoscopic repair with lumbo-peritoneal shunt insertion

BackgroundSpontaneous cerebrospinal fluid (CSF) leaks are associated with high morbidity and recurrence rates. Most cases had increased intracranial pressure (ICP) on presentation. There is still controversy regarding the use of lumbo-peritoneal shunt to prevent its recurrence.AimThis study was conducted to evaluate the impact of lumbo-peritoneal CSF shunt following the initial as well as recurrent repair of spontaneous CSF leaks to avoid recurrence.MethodsA retrospective cohort study reviewed patients with recurrent spontaneous CSF leaks over a 4-year period. All patients had increased ICP and were subjected to endoscopic repair and lumbo-peritoneal shunt procedure.ResultsEighteen patients were included in this study. Most patients were obese (BMI = 33.6 ± 1.8 kg/m2) women (88.9%), with sleep apnea syndrome (77.8%). All patients presented with headache and visual complaints. Meningitis was recorded in two patients (11.1%). The most common sites of leakage were the cribriform (66.7%), followed by both cribriform and ethmoidal (16.7%), sphenoid (11.1%), and ethmoidal (5.6%) bones. The mean defect size was 5.1 ± 1.1 mm. About one third of cases had multiple defects. Encephalocele and meningocele were encountered in 61.1% and 66.7% of cases, respectively. The mean preoperative CSF pressure was 36.5 ± 1.7 mm H2O. Lumbo-peritoneal shunt was inserted for all our patients. The failure rate of repair was 11.1%.ConclusionSuccess rate is higher in patients with spontaneous CSF leaks and CSF hypertension treated by lumbo-peritoneal shunt. Future prospective studies with larger sample sizes should confirm the efficacy and safety of this management plan.

Interpretation of lumbar cerebrospinal fluid leukocytosis after cranial surgery: The relevance of aseptic meningitis

Raised white cell count (WCC) in lumbar CSF is a commonly used marker of meningitis. The effect of cranial neurosurgery per se on lumbar WCC is not established. At this single centre, many patients undergo ICPM followed by lumboperitoneal shunt (LPS), with lumbar CSF WCC samples taken during insertion. We aimed to determine the effect of ICP bolt insertion on lumbar CSF WCC. We undertook a retrospective analysis of lumbar CSF samples in patients who had recently undergone 24-h ICPM. Thirty-three patients (16F:7M) aged 43.31 ± 12.1 years (mean ± SD) had lumbar CSF samples after ICPM. Fourteen had CSF sampled within 6 weeks and 19 after 6 weeks of ICPM. Twenty-five samples were taken during LPS insertion, 5 during lumbar drainage/puncture and 3 during LPS revision. All 33 patients were afebrile at the point of CSF sampling. The mean lumbar WCC within 6 weeks of ICPM was significantly higher than the mean lumbar WCC after 6 weeks, being 15.4 ± 18.0 and 2.32 ± 1.79 cells/microlitre respectively respectively. There was no significant increase in RBC. In patients with raised CSF WCC, 60% of raised WCC were predominantly lymphoctyes and 40% predominantly neutrophils. Only one patient grew an organism (S. aureus). We conclude that lumbar CSF WCC can be raised following minor intracranial surgery, despite no clinical sign of infection. We caution against using lumbar CSF WCC values independently as the only marker of infection following neurosurgery.

Image-Guided Stereotactic Ventricular Catheter Placement for Refractory Idiopathic Intracranial Hypertension: Accuracy and Effectiveness

AbstractBackground: Although lumboperitoneal shunt (LPS) is a common procedure for surgical management of idiopathic intracranial hypertension (IIH). However, many studies doc-umented a high failure and complications rate. Ventricular shunts were not commonly used for surgical management IIH due to the difficulty of inserting a shunt into normal or slit ventricles. Also, stereotactic surgery not available in every hospital.Aim of the Study: This article retrospectively evaluate the accuracy, efficacy, and safety of using stereotactic image-guided insertion of ventricular catheter in patients with IIH.Patients and Methods: The authors reviewed the clinical records of all patients in whom stereotaxy was used to guide the placement of a ventricular catheter for IIH. Stereotactic guided ventricular catheter placements were performed on sixteen patients presenting with clinical manifestation of IHH to target the frontal horn of the lateral ventricle after failure of traditional medical or previous surgical treatment. Results: We had fourteen females and two males. Their age ranged from 20 to 45 years (average 29.7). The mean follow-up period was 43.9 months (ranged from 10 to 84 months). Eleven patients had previous LPS insertion with at least one trial of revision. Five patients subjected to stereotactic VPS as a first procedure. Accurate ventricular catheter place-ment was done from the first trial in all patients which was confirmed on postoperative CT scan. Four patients underwent stereotactic ventriculo-atrial shunts due to decrease CSF absorptive capacity of peritoneal cavity due to multiple lumboperitoneal shunt revision. All patients showed improve-ment or stabilization of their visual manifestation after ven-tricular shunt insertion. Headache improved in fourteen patients whereas two patients still had headache that respond to medical treatment. We had no mortality and two patients required shunt revision.Conclusions: Image-guided stereotactic ventricular cath-eter placement is an effective, safe and durable management option that can help in management of IIH when the ordinary medical and surgical methods fail. Also it may be the first choice in certain selected cases.

Lumboperitoneal shunt insertion without fluoroscopy guidance: Accuracy of placement in a series of 107 procedures

Background: Lumboperitoneal (LP) shunts were the mainstay of cerebrospinal fluid diversion therapy for idiopathic intracranial hypertension (IIH). The traditionally cited advantage of LP shunts over ventriculoperitoneal (VP) shunts is the ease of insertion in IIH. This needs to be placed at the level of L3/4 to be below the level of the spinal cord. The objective of this study was to analyse the position of LP shunts inserted without portable fluoroscopy guidance. Methods: A retrospective analysis of radiology was performed for patients who underwent lumboperitoneal shunts between 2006 and 2016 at the National Hospital for Neurology and Neurosurgery. Patients who had insertion of a LP shunt without fluoroscopy guidance were selected. Patients without post-procedural imaging were excluded. A retrospective analysis of the clinical notes was also performed. Results: Between 2006 and 2016, 163 lumboperitoneal shunts were inserted in 105 patients. A total of 56 cases were excluded due to lack of post-procedural imaging; therefore, 107 post-procedural x-rays were reviewed. In 17 (15.8%) cases the proximal end of the LP shunt was placed at L1/L2 level or above. Conclusions: Insertion of LP shunts without portable fluoroscopy guidance gives a 15.8% risk of incorrect positioning of the proximal end of the catheter. We suggest that x-ray is recommended to avoid incorrect level placement. Further investigation could be carried out with a control group with fluoroscopy against patients without.

Lumboperitoneal shunt insertion without fluoroscopy guidance: Accuracy of placement in a series of 107 procedures

Background: Lumboperitoneal (LP) shunts were the mainstay of cerebrospinal fluid diversion therapy for idiopathic intracranial hypertension (IIH). The traditionally cited advantage of LP shunts over ventriculoperitoneal (VP) shunts is the ease of insertion in IIH. This needs to be placed at the level of L3/4 to be below the level of the spinal cord. The objective of this study was to analyse the position of LP shunts inserted without portable fluoroscopy guidance. Methods: A retrospective analysis of radiology was performed for patients who underwent lumboperitoneal shunts between 2006 and 2016 at the National Hospital for Neurology and Neurosurgery. Patients who had insertion of a LP shunt without fluoroscopy guidance were selected. Patients without post-procedural imaging were excluded. A retrospective analysis of the clinical notes was also performed. Results: Between 2006 and 2016, 163 lumboperitoneal shunts were inserted in 105 patients. A total of 56 cases were excluded due to lack of post-procedural imaging; therefore, 107 post-procedural x-rays were reviewed. In 17 (15.8%) cases the proximal end of the LP shunt was placed at L1/L2 level or above. Conclusions: Insertion of LP shunts without portable fluoroscopy guidance gives a 15.8% risk of incorrect positioning of the proximal end of the catheter. We suggest that x-ray is recommended to avoid incorrect level placement. Further investigation could be carried out with a control group with fluoroscopy against patients without.

Lumboperitoneal shunt insertion without fluoroscopy guidance: Accuracy of placement in a series of 107 procedures.

Background: Lumboperitoneal (LP) shunts were the mainstay of cerebrospinal fluid diversion therapy for idiopathic intracranial hypertension (IIH). The traditionally cited advantage of LP shunts over ventriculoperitoneal (VP) shunts is the ease of insertion in IIH. This needs to be placed at the level of L3/4 to be below the level of the spinal cord. The objective of this study was to analyse the position of LP shunts inserted without portable fluoroscopy guidance. Methods: A retrospective analysis of radiology was performed for patients who underwent lumboperitoneal shunts between 2006 and 2016 at the National Hospital for Neurology and Neurosurgery. Patients who had insertion of a LP shunt without fluoroscopy guidance were selected. Patients without post-procedural imaging were excluded. A retrospective analysis of the clinical notes was also performed. Results:Between 2006 and 2016, 163 lumboperitoneal shunts were inserted in 105 patients. A total of 56 cases were excluded due to lack of post-procedural imaging; therefore, 107 post-procedural x-rays were reviewed. In 17 (15.8%) cases the proximal end of the LP shunt was placed at L1/L2 level or above. Conclusions:Insertion of LP shunts without portable fluoroscopy guidance gives a 15.8% risk of incorrect positioning of the proximal end of the catheter. We suggest that x-ray is recommended to avoid incorrect level placement. Further investigation could be carried out with a control group with fluoroscopy against patients without.

Gravity-assisted valve (GAV) systems to prevent low-pressure headaches in patients with lumboperitoneal shunts

Objectives: Low-pressure symptoms after lumboperitoneal (LP) shunting for idiopathic intracranial hypertension (IIH) remain a significant problem. Gravity-assisted valves (GAV) operate at a higher pressure in a vertical position and therefore aim to reduce postural over-drainage. We audited patients with GAV valves inserted in their shunt system to assess their efficacy in reducing low-pressure symptoms and ascertain whether the additional cost of such device can be justified.Method: Using a standard proforma, we reviewed patient medical notes and recorded indications and post-operative outcomes in symptom control.Results: In total, 24 patients had the GAV system inserted, 12 had low-pressure symptoms after LP and had LP shunts inserted with GAV valves and 11 in developed low-pressure symptoms after insertion of plane LP shunts and had GAV valves added as secondary procedures. One patient was excluded from the study because the indication for the GAV system was secondary to the presence of low lying cerebellar tonsils (secondary Chiari) rather than headache in a patient with IIH who had undergone previous LP shunt insertion. The GAV system was introduced to prevent further tonsillar decent.Out of 23 patients, 17 patients who had the system inserted to prevent or improve low-pressure symptoms reported improvement in their symptoms.Conclusions: GAV inserted into LP shunts were effective in reducing low-pressure headaches induced by changes in posture whilst still sufficiently lowering ICP to ameliorate high-pressure symptoms.

Laparoscopic-assisted Peritoneal Shunt Insertion for Ventriculoperitoneal and Lumboperitoneal Shunt Placement: An Institutional Experience of 53 Consecutive Cases.

The purpose of this study was to describe operative times, complication rates, and outcomes following laparoscopic placement of the peritoneal catheter in ventriculoperitoneal (VP) and lumboperitoneal (LP) shunt insertion. A retrospective review was performed of those who underwent laparoscopic-assisted VP or LP shunt insertion from July 2007 to August 2011. The study included 53 consecutive patients (35 women and 18 men). Mean age was 51 years (range, 16 to 83 y), mean BMI was 27.6 (range, 16 to 54), and 35.8% of the patients had previous abdominal surgery. Mean operative time for VP shunt placement was 68.2 ± 19.0 minutes, and for LP shunt placement 84 ± 12.4 minutes. There were no intraoperative complications, and conversion to minilaparotomy was 0%. There were 2 distal catheter-associated complications. Laparoscopic-assisted VP/LP shunt placement is associated with a low incidence of distal catheter malfunction. Direct visualization of shunt placement into the peritoneal cavity is a major advantage making it a viable alternative over traditional techniques.

Complications of Lumboperitoneal Shunts for Idiopathic Intracranial Hypertension

For the past half century, the mainstay of cerebrospinal fluid (CSF) shunting for idiopathic intracranial hypertension (IIH) has been lumboperitoneal (LP) shunt surgery. LP shunts have been associated with higher failure rates compared to ventriculoperitoneal shunts. However, there is no uniformity in the reporting of complication and surgical revision rates. The goals of this study were to understand better the complications and surgical revision rates associated with LP shunt insertion in IIH patients with the objective of providing better information about the different therapeutical option outcomes when counseling for a better informed consent. Twenty-six patients with IHH undergoing lumboperitoneal shunt surgery for the first time by the senior author at an academy tertiary-care institution were retrospectively reviewed. Presence of complications and surgical revisions were the two main outcome variables. Logistic regression analysis was used first to assess if there was a correlation between preoperative patient characteristics and complications and second to evaluate if there was any association between preoperative patient characteristics or postsurgical complications and surgical revision.

Use of lumboperitoneal shunts with the Strata NSC valve: a single-center experience

The lumboperitoneal (LP) shunt with the adjustable PS Medical Strata NSC LP valve and small lumen peritoneal catheter was introduced in the authors' unit in 2007. The object of this study was to audit the unit's experience with this new shunt system. The authors performed a retrospective review of the clinical records of patients who underwent Strata NSC LP shunt insertion. Demographic and clinical data as well as information about complications and revisions were reported. Between August 2007 and November 2009, 20 patients underwent placement of an LP shunt with an adjustable Strata NSC valve and small lumen peritoneal catheter at the authors' institution. Their mean age was 40.3 years and the mean duration of follow-up was 12 months. Preoperatively, 18 patients had headache and 15 patients had visual signs and symptoms. Fourteen of the 18 patients with preoperative headache did not complain of headache postoperatively, and 4 had headache that was found not to be related to shunt function. Two of the patients with preoperative visual complaints had ongoing visual problems postoperatively. None of the patients had infection or subdural hematoma. The only overdrainage symptoms occurred in association with spontaneous readjustment of the valve and resolved when the valve was reset. Thirteen patients (65%) did not require shunt revision. Seven patients (35%) required 13 shunt exploration or revision procedures, mainly due to distal obstruction. Placement of an LP shunt failed to completely resolve the raised intracranial pressure problem in 2 patients. The use of the Strata NSC valve and small lumen peritoneal catheter is effective in treating pseudotumor cerebri and is beneficial in terms of markedly reducing overdrainage complications compared with other reported series of cases in which an LP shunt has been placed. However, the use of the Strata NSC valve and small lumen peritoneal catheter did not have a marked impact on other causes of shunt failure, particularly distal obstruction.

Transient unilateral ophthalmoplegia without papilledema in a child with intracranial hypertension

Intracranial hypertension is usually presented with papilledema and headache. Complete ophthalmoplegia without papilledema is a very rare finding of intracranial hypertension in children. A 5-year-old male patient with unilateral ophthalmoplegia due to increased intracranial pressure is presented. The fundoscopic examination and the magnetic resonance imaging of the brain were normal. He underwent lumboperitoneal shunt insertion for intracranial hypertension and the ophthalmoplegia was resolved one month later. Complete ophthalmoplegia without papilledema may occur following intracranial hypertension. Prompt and accurate diagnosis should be done and appropriate treatment to reduce the pressure should be performed to save the life of the children.

Lumboperitoneal shunt placement using computed tomography and fluoroscopy in conscious patients

The authors have developed a minimally invasive lumboperitoneal shunt placement procedure conducted after administration of a local anesthetic. The procedure involves placing a guide wire and a peel-away sheath under fluoroscopic and CT guidance. Between June 2004 and August 2006, 40 patients (21 men and 19 women; mean age 72.5 years [range 33-86 years]) underwent surgery. A Codman Hakim programmable valve system (82-3844, Codman & Shurtleff, Inc.) was used for the procedure. The mean operating time was 53 minutes, and 7 patients (17.5%) developed shunt dysfunction complications. These complications comprised an infected shunt valve in 2 patients, postoperative lower-limb pain in 1 patient, and shunt obstruction (caused by debris and hemorrhage) at the ventral and lumbar ends in 2 patients each. This procedure is less invasive than conventional lumboperitoneal shunt insertion and could be performed as an outpatient surgery for treatment of idiopathic normal-pressure hydrocephalus.

Bilateral jugular foraminal stenosis in a patient with benign osteopetrosis associated with pseudotumor cerebri syndrome

One of the prominent causes of pseudotumor cerebri (PTC) syndrome is increased impedance of the venous outflow tracts of the brain. Theoretically, this is a justified mechanism for raised intracranial pressure; yet, there had been few cases of such a scenario reported in the literature, and to the authors' knowledge no case of PTC due to benign osteopetrosis has been reported to date. The present case occurred in a 19-year-old woman with a constellation of signs and symptoms compatible with PTC syndrome, whose radiological and laboratory studies confirmed the diagnosis of osteopetrosis. Magnetic resonance venography demonstrated bilateral jugular foraminal stenosis regarding the underlying disease process. The patient did well after she underwent a lumboperitoneal shunt insertion procedure.

Intracerebral hematoma following lumboperitoneal shunt insertion: a rare case report

Lumboperitoneal shunting is widely used for the surgical management of pseudotumor cerebri and other pathologies such as communicating hydrocephalus. Although it is a safe method, it could be associated with complications including subarachnoid hemorrhage, subdural and rarely intracerebral hematoma. A 44-year-old female applied to our clinic with complaints of severe headache, retroorbital pain and blurred vision. Lumbar puncture demonstrated cerebrospinal fluid opening pressure of cmH2O. A non-programmable lumboperitoneal shunt with two distal slit valves was inserted due to pseudotumor cerebri. She deteriorated shortly after surgery. Immediate cranial computed tomography scan revealed a right parietal intracerebral hematoma. Development of intracerebral hematoma following lumboperitoneal shunt is a rare complication. We discuss this rare event accompanied by the literature.

Altered subarachnoid space compliance and fluid flow in an animal model of posttraumatic syringomyelia.

A histologic study of cerebrospinal fluid tracers in Sprague-Dawley rats undergoing lumboperitoneal shunt insertion in the excitotoxic animal model of posttraumatic syringomyelia (PTS). To determine the effects of cerebrospinal fluid (CSF) diversion from the subarachnoid space on perivascular flow (PVS) and syrinx formation in posttraumatic syringomyelia. In an animal model of PTS, fluid enters syringes from the subarachnoid space via perivascular spaces. Preferential PVS flow occurs at the level of the syrinx. It has been suggested that arachnoiditis predisposes to posttraumatic syringomyelia formation by obstructing subarachnoid cerebrospinal fluid flow and enhancing perivascular flow. Thirty-two male Sprague-Dawley rats were investigated using the CSF tracer horseradish peroxidase (HRP), the excitotoxic model of PTS, and lumboperitoneal shunt insertion. Five experimental groups consisted of normal controls, syrinx only and shunt only controls, and shunt insertion before or after syrinx formation. In all groups except normal controls, CSF flow studies were performed 6 weeks after the final intervention. Grading scales were used to quantify HRP staining. All excitotoxic model animals formed syringes. Perivascular flow was greatest at the level of the syrinx. Cerebral cortex perivascular flow was significantly reduced after shunt insertion in animals with a syrinx (P < 0.05). Shunt insertion did not alter syrinx length or size. There were no significant differences between shunt and syrinx first groups. Increasing caudal subarachnoid space compliance with a shunt does not affect local CSF flow into the spinal cord and syrinx. These results suggest that localized alterations in compliance, as opposed to obstruction from traumatic arachnoiditis, may act as an important factor in syrinx pathogenesis.