The Role of 3D Reconstruction of the Skull in Patients with Suspected Shunt Malfunction

Background: Mechanical shunt malfunction may lead to significant morbidity and mortality. Shunt series assessments help evaluate shunt integrity; however, they are of limited value in the area of the skull due to skull curvature, thickness, and air sinuses. We describe the role of 3D bone reconstruction CT (3DCT) in demonstrating the shunt integrity over the skull, comparing this technique to skull X-rays (SXR). Methods: Data were collected retrospectively for shunted patients with concurrent SXR and 3DCT and for patients presenting with shunt failures at the region of the skull, including clinical course and radiological findings. We compared the SXR and 3DCT findings. The 3DCT was reconstructed from standard diagnostic CT protocols performed during evaluation of suspected shunt malfunction and not thin-slice CT protocols. Results: Forty-eight patients with 57 shunts underwent SXR and 3DCT. Interobserver agreement was high for most variables. Both SXR and 3DCT had a high sensitivity, specificity, and accuracy identifying tubing disconnections (between 0.83 and 1). Full valve type and setting were significantly more accurate based on SXR versus 3DCT (>90 vs. <20%), and valve integrity was significantly more readily verified on 3DCT versus SXR (100 vs. 52%). Conclusions: 3DCT and SXR complement each other in diagnosing mechanical shunt malfunctions over the skull. The main limitation of 3DCT is identification of valve type and settings, which are clearer on SXR, while the main limitation of SXR is a less ability to evaluate valve integrity. 3DCT also enables an intuitive 3D understanding of the shunt tubing over the skull.

Image quality of EOS low-dose radiography in comparison with conventional radiography for assessment of ventriculoperitoneal shunt integrity

OBJECTIVEPatients with shunted hydrocephalus often accumulate high levels of radiation over their lifetimes during evaluation of hardware integrity. Current practice involves the use of a series of conventional radiographs for this purpose. Newer low-dose EOS radiography is currently used to evaluate scoliosis but has not been explored to evaluate shunt integrity on a large scale. The goal of this study was to compare the quality of imaging using EOS low-dose radiography to conventional radiography to evaluate shunt tubing.METHODSA retrospective chart review was performed on 57 patients who previously had both conventional radiographs and low-dose EOS images of their cerebral shunt tubing from 2000 to 2018. Patient demographics (age, sex, type of shunt tubing, primary diagnosis) were collected. Conventional radiographic images and low-dose EOS images were independently analyzed by a neurosurgeon and neuroradiologist in three categories: image quality, delineation of shunt, and distinction of shunt compared to adjacent anatomy.RESULTSAll patients had shunted hydrocephalus due to spina bifida and Chiari type II malformation. Ratings of EOS and conventional radiographic images by both raters did not differ significantly in terms of image quality (rater 1, p = 0.499; rater 2, p = 0.578) or delineation of shunt (p = 0.107 and p = 0.256). Conventional radiographic images received significantly higher ratings than EOS on the ability to distinguish the shunt versus adjacent anatomy by rater 1 (p = 0.039), but not by rater 2 (p = 0.149). The overall score of the three categories combined was not significantly different between EOS and conventional radiography (rater 1, p = 0.818; rater 2, p = 0.186). In terms of cost, an EOS image was less costly than a conventional radiography shunt series ($236–$366 and $1300–$1547, respectively). The radiation dose was also lower for EOS images, with an effective dose of 0.086–0.140 mSv compared to approximately 1.6 mSv for a similar field of view with conventional radiography.CONCLUSIONSThe image quality of low-dose EOS radiography does not significantly differ from conventional radiography for the evaluation of cerebral shunts. In addition, EOS affords a much lower radiation dose and a lower cost.

Supracollicular fluid accumulation type 3 with concurrent hydrocephalus in a five-month-old crossbreed dog

A five-month-old crossbreed dog was referred with a 36-hour history of cervical hyperaesthesia. CT and MRI of the head and neck identified supracollicular fluid accumulation type 3 with concurrent hydrocephalus, syringohydromyelia and cerebellar herniation. Medical treatment consisting of analgesia and mannitol was instigated, and once the patient was stabilised a supracollicular-peritoneal shunt system was placed. The patient initially responded very well to this treatment. Six days postoperatively, the patient sustained disconnection of the shunt system at the level of the pressure valve and distal shunt tubing. Revision surgery to repair the shunt was performed without further complication. The dog returned to being neurologically normal within four weeks. One year postoperatively, the patient remains neurologically normal with no further clinical signs nor shunt system complications.

ETV in tuberculous meningitis with hydrocephalus and allergic reaction to VP shunt: a case report

Hydrocephalus is one of the most common complications of tuberculous meningitis (TBM) occurring in up to 85% of patients with the disease. The placement of a ventriculoperitoneal (VP) shunt is the most common form of treatment for hydrocephalus in tuberculous meningitis (TBM). Although allergic reactions to the silicone in shunt device are very rare, the authors describe a case of silicone allergy causing multiple VP shunt revisions. Alternative choice is endoscopic third ventriculostomy (ETV), but it is debatable. ETV has variable success in these patients and is generally not advisable in patients in the acute stages of the disease. A 19-year-old woman with hydrocephalus in tuberculous meningitis, who had undergone multiple VP shunt revisions, presented with shunt malfunction caused by allergic reaction of the tissue surrounding the shunt tubing. Laboratory examination demonstrated high level IgE, high level ESR, and PCR-TBC Positive, related to the allergic reaction. Patient with ETV success score of 50. Patients received ETV and release VSS Shunt. ETV has success in these patients. VP Shunts complications remain a difficult problem in neurosurgical clinical practice. The most typical complications are mechanical obstruction and infection. Allergy to the silicone shunt tubing is quite rare. Silicone allergy is an even more rare occurrence because of its high biocompatibility and low biological reactivity. It is a challenge for ETV when TBM has difficulty to recognize anatomical landmarks on this patient. It could also consider in patients who have shunt failure, and might be a better option than shunt revision.

Effect of Protein Concentration on the Flow of Cerebrospinal Fluid Through Shunt Tubing

BACKGROUND: Protein levels in cerebrospinal fluid (CSF) are commonly thought to be related to sterile shunt malfunction. OBJECTIVE: To investigate the relationship between protein concentration and flow through CSF shunt tubing and a shunt valve. METHODS: New and explanted shunt catheters were tested with and without a shunt valve attached at various protein concentrations. The protein concentrations used were 0.5, 2, 5, and 10 g/L. A flask with artificial CSF attached to the proximal end provided flow. The flow was allowed to stabilize over 1 hour, and then the change in pressure between the proximal and distal end of the catheter was measured and recorded. The resistance to flow was calculated for new and explanted catheters for adult shunt systems, as well as with the addition of a programmable siphon control valve. The resistance was examined after the addition of various protein concentrations to a normal CSF solution. RESULTS: Both new and explanted catheters exhibited a decrease in the resistance to flow with higher concentrations of protein. CONCLUSION: In our laboratory setting, there was decreased resistance of adult CSF shunt catheters with and without a valve as the concentration of protein in the CSF increased. The decrease in the resistance of CSF shunt catheters with the addition of protein to the CSF may be related to the lowering of surface tension. This is the first study to examine the effects of varying protein concentrations across different lengths of shunt tubing for both new and explanted catheters.

Solid noninfectious growing masses over cerebrospinal fluid shunts: report of 3 cases

The authors describe 3 children who presented with progressively enlarging skin-covered solid masses over the shunt catheter in the neck/clavicular region. The authors reviewed the clinical, laboratory, pathological, radiographic, and follow-up data for all 3 patients and reviewed the literature on the subject. The patients had no clinical evidence of an infectious process. Surgical exploration revealed that masses were surrounding and encasing the shunt tubing to which they were strongly attached. Pathological studies of the tissues demonstrated varying degrees of exuberant chronically inflamed granulation tissues, interstitial fibrosis, and dystrophic calcification. One patient had associated thinning of the skin overlying the mass and subsequently developed ulceration. No infectious organisms were observed. The cerebrospinal fluid aspirates from the shunts did not yield any organisms. There has been no recurrence of the masses. The presence of a growing mass over the shunt tube in the neck or the chest region without clinical evidence of infection does not indicate that the mass should be treated with antibiotics and complete shunt removal. Rather, the mass can be cured by extirpation and with “bypass” new shunt tubing locally.

Bucket and straw technique to facilitate passage of a ventriculoperitoneal shunt through the distal tunneling sheath

Placement of a ventriculoperitoneal shunt (VPS) is a procedure comprising many small steps. Difficulties and delays can arise when passing the distal shunt tubing down the distal tunneling sheath during surgery. The authors of this report describe a simple technique for quickly passing the distal catheter of a VPS through the tunneler sheath, whereby the sheath is used as a fluid tube to allow the distal catheter to be drawn through the fluid tube under suction pressure. The plastic sheath that surrounds the shunt tunneler device is used as a fluid tube, or “straw,” with the proximal aperture submerged into a bucket of sterile irrigation liquid containing the distal catheter. Suction pressure is placed against the distal aperture of the tunneler, and the shunt catheter is quickly drawn through the sheath. No special equipment is required. In time trials, the bucket and straw technique took an average of 0.43 seconds, whereas traditional passage methods took 32.3 seconds. The “bucket and straw” method for passing distal shunt tubing through the tunneler sheath is a technique that increases surgical efficiency and reduces manual contact with shunt hardware.