Ahmed K. Toma, Muhammad Dherijha, Neil D. Kitchen and Laurence D. Watkins
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.
Ahmed K. Toma, Andrew Tarnaris, Neil D. Kitchen and Laurence D. Watkins
Managing symptomatic ventriculoperitoneal shunts with no clear evidence of shunt malfunction either clinically or radiologically can be a difficult task. The aim of this study was to assess intracranial pressure (ICP) monitoring as a method of investigating shunt function.
The authors performed a retrospective analysis of 38 continuous ICP monitoring procedures done in patients with ventriculoperitoneal shunts and suspected shunt malfunction.
Thirty-eight procedures were performed in 31 patients between January 2005 and October 2008. Sixteen recordings were normal, 6 revealed overdrainage or low pressure, 11 indicated underdrainage or high pressure, and 5 showed variable shunt function. Based on the findings after 20 procedures (53%), patients were treated conservatively: 4 by readjusting the valve setting and 16 by referral to the headache neurologist for medical treatment. Forty-five percent of the conservatively treated patients improved. Surgical exploration was undertaken following 18 procedures (47%); 72% of the surgically treated patients improved.
Continuous ICP monitoring using an intraparenchymal probe is a safe and effective method of investigating adult hydrocephalus.
Ahmed K. Toma, Andrew Tarnaris, Joan P. Grieve, Laurence D. Watkins and Neil D. Kitchen
In this paper, the authors' goal was to compare the artifact induced by implanted (in vivo) adjustable shunt valves in spin echo, diffusion weighted (DW), and gradient echo MR imaging pulse sequences.
The MR images obtained in 8 patients with proGAV and 6 patients with Strata II adjustable shunt valves were assessed for artifact areas in different planes as well as the total volume for different pulse sequences.
Artifacts induced by the Strata II valve were significantly larger than those induced by proGAV valve in spin echo MR imaging pulse sequence (29,761 vs 2450 mm3 on T2-weighted fast spin echo, p = 0.003) and DW images (100,138 vs 38,955 mm3, p = 0.025). Artifacts were more marked on DW MR images than on spin echo pulse sequencse for both valve types.
Adjustable valve–induced artifacts can conceal brain pathology on MR images. This should influence the choice of valve implantation site and the type of valve used. The effect of artifacts on DW images should be highlighted pending the development of less MR imaging artifact–inducing adjustable shunt valves.