Weight and Abdominal Pressure-Induced Shunt Trouble in Patients With Shunted Normal Pressure Hydrocephalus: A Comprehensive Study on Pressure Environment of Shunt System.

Objectives: We identified a new type of shunt malfunction (SM) in patients with normal pressure hydrocephalus (NPH). It is induced by weight change and can be treated with valve readjustment. There were two types of SM as follows: Underdrainage induced by the weight gain and overdrainage induced by the weight loss. This study aims to elucidate this mechanism by assessing the shunt pressure environment. Methods: The total pressure environment of the shunt system was prospectively studied in patients with shunted NPH at Osaka Medical College Hospital from 1999 to 2005. We measured the pressure environment during the initial pressure setting of the valve by the intracranial pressure (ICP) guide, after setting the valve, and when SM was suspected. We evaluated ICP, intra-abdominal pressure (IAP), and hydrostatic and perfusion pressures of the shunt system in the sitting and supine positions. The target ICP for valve setting was empirically set at the range from -8 to -13 mm Hg in the sitting position, referring to the external auditory meatus. During the study period, we identified five cases of SM induced by weight change and assessed the changes in the pressure environment across pre-SM, SM, and post-SM. Results: In four cases of underdrainage, gait disturbance worsened with an average weight gain of 6.8 ± 1.2 kg. With weight gain, IAP and ICP increased by 8.8 ± 1.6 and 4.8 ± 1.0 mm Hg, respectively. Consequently, ICP increased to -6.5 ± 1.9 mm Hg. One overdrainage patient developed an asymptomatic chronic subdural hematoma (CSDH) with a weight loss of 10 kg. With the weight loss, both IAP and ICP decreased by 5 mm Hg, and concomitantly, ICP decreased to -18 mm Hg. In all patients, the valve readjustment restored their ICP to the target pressure. After the valve readjustment, the gait disturbance improved immediately, and the CSDH disappeared after 1 month. Conclusion: In patients with shunts, the weight change was linked to ICP via IAP. Due to the weight change, the underdrainage occurred when ICP was above the target pressure, and the overdrainage occurred when ICP was below it. We named this SM as the weight and abdominal pressure-induced shunt trouble. The patients with SM along with weight changes should be the first to be tried for the valve readjustment.

Fluoroscopic-Guided Paramedian Approach for Lumbar Catheter Placement in Cerebrospinal Fluid Shunting: Assessment of Safety and Accuracy.

BACKGROUND: Spinal catheter insertion in lumboperitoneal (LP) shunt surgery for idiopathic normal pressure hydrocephalus (iNPH) is frequently associated with technical difficulties especially in patients with obesity and elderly patients with vertebral deformities. OBJECTIVE: To elucidate the accuracy and safety of image-guided spinal catheter placement using a paramedian approach (PMA). METHODS: We retrospectively analyzed 39 consecutive iNPH patients treated by LP shunting with spinal catheter insertion via the PMA. The success rate of catheter placement and the number of changes in puncture location were evaluated. Accuracy of catheter insertion was assessed by measuring both vertical and horizontal deviations in the point of catheter dural penetration from the center of the interlaminar space. RESULTS: The success rate of catheter placement was 100% (39/39). The difficulty rate for catheter insertion, measured by the number of changes in puncture location, was 2.6% (1/39). No bloody punctures or surgical infections were observed. Accuracy of catheter insertion, measured as the degree of deviation, was 0.5 ± 1.9 mm horizontally and 0.0 ± 2.4 mm vertically. The rates of minor complications, including caudal catheter insertion, transient low-pressure headache, and root pain, were 5.1% (2/39), 10.4% (4/39), and 0% (0/43), respectively. Subdural hematoma requiring surgical intervention occurred in 1 case (2.6%). During the mean follow-up period of 36 mo, spinal catheter rupture at the level of the spinous processes was not observed. CONCLUSION: Fluoroscopic-guided spinal catheter placement via the PMA was safe, accurate, and reliable, even for use in geriatric and obese patients.

Continuous Blood Glucose Monitoring May Detect Carotid Occlusion Intolerance during Carotid Artery Stenting.

BACKGROUND: The frequency of the occurrence of adverse events associated with carotid artery stenting (CAS) is usually low, but serious adverse events such as cerebral hyperperfusion syndrome (CHS) may occur. Real-time monitoring is ideal for the early detection of adverse events during the surgical procedure. This study aimed to evaluate continuous blood glucose (BG) monitoring for the detection of adverse events during CAS. METHODS: Forty patients undergoing scheduled CAS were prospectively enrolled. An artificial pancreas was used for continuous BG monitoring (once per minute), using venous blood extracted at a rate of 2 mL/hr during CAS. The primary endpoint was a correlation between BG change and adverse events. RESULTS: CAS was discontinued in 1 patient, and BG was not measured in 5 patients (12.5%) because of the inability to extract blood. Among 34 evaluable patients, no patient developed CHS, but 3 patients (9%) experienced carotid occlusion intolerance. During CAS, BG was significantly higher in patients with carotid occlusion intolerance (median: 5 mg/dL) than in patients without carotid occlusion intolerance (median: 0 mg/dL) (P = 0.0221). A cutoff BG value ≥4 mg/dL during CAS showed 50% sensitivity and 100% specificity for the detection of carotid occlusion intolerance. There was no significant correlation between BG change and other adverse events. CONCLUSIONS: BG elevation may help detect carotid occlusion intolerance although it is still unknown whether BG monitoring can detect CHS. Further studies should validate that a cutoff BG elevation value of ≥4 mg/dL during CAS indicates carotid occlusion intolerance.

A new mathematical model for pattern formation by cranial sutures.

Cranial sutures are narrow mesenchymal tissues that connect skull bones to each other. Given that they serve as growth centers in the skull, these undifferentiated tissues play crucial roles in skull development. Cranial sutures are also of clinical importance, because the premature fusion of skull bones results in a pathological condition called craniosynostosis. In newborns, skull sutures are wide and straight; during adolescence, they become thinner and start winding to form an interdigitating pattern. From a functional aspect, as the degree of interdigitation becomes larger, the strength of the connection between bones increases. However, the mechanisms underlying the maintenance of mesenchymal narrow bands or formation of interdigitation remain poorly understood. In the present study, we presented a new mathematical model that can reproduce the suture width maintenance and interdigitation formation. We can predict the width of the mesenchyme bands and wavelengths of suture interdigitations from the model.

Two forms of synaptic plasticity with distinct dependence on age, experience, and NMDA receptor subtype in rat visual cortex.

In visual cortex, NMDA receptor (NMDAR) properties depend primarily on NR2A and NR2B subunits, and NR2 subunit composition changes with age and visual experience. We examined the roles of these NR2 subunits in activity-dependent long-term modification of synaptic responses, which were evoked in layer 2/3 cells by stimulation of layer 4 in rat visual cortical slices. We used theta-burst stimulation (TBS) of presynaptic fibers or low-frequency stimulation paired with postsynaptic depolarization, which has been commonly used to induce NMDAR-dependent long-term potentiation (LTP) in visual cortex. In pyramidal cells, however, TBS produced long-term depression (LTD) at inhibitory synapses rather than LTP at excitatory synapses. This was observed in association with LTP of extracellular field potentials that reflect postsynaptic potentials in a population of cells (field-LTP). This result is inconsistent with the previous view that field-LTP reflects LTP of excitatory connections. However, pairing stimulation produced LTP at excitatory synapses of pyramidal cells frequently during development but rarely in adulthood. In contrast, inhibitory LTD and field-LTP occurred similarly in both developing and mature cortex. Experiments using NR2B selective and NR2 subunit nonselective NMDAR antagonists demonstrated that NR2A- and NR2B-containing NMDARs contribute selectively to inhibitory LTD-field-LTP and excitatory LTP, respectively. In addition, we found that the developmental decline in the NR2B component was paralleled by a decline in the incidence of excitatory LTP, and these declines were both prevented by dark rearing. These results implicate NR2 subunit composition in the regulation of neocortical plasticity and demonstrate differential subunit regulation at inhibitory and excitatory connections.

Age and experience dependence of N-methyl-D-aspartate receptor-independent long-term potentiation in rat visual cortex.

Dark rearing prolongs the critical period for experience-dependent modification of visual cortical functions. To test whether long-term potentiation (LTP) could potentially underlie this modification, we studied the age and experience dependence of LTP, induced in layer 2/3 cells by layer 4 stimulation continued for 15 min at 2 Hz, in rat visual cortical slices. This LTP was independent of N-methyl-D-aspartate receptor (NMDAR) activation, but it likely required Ni(2+)-sensitive Ca(2+) channel activation for induction. LTP occurred frequently during development, but rarely in adulthood. Dark rearing prevented this developmental decline. These age- and experience-dependent changes were demonstrated in both excitatory postsynaptic potentials recorded from pyramidal cells under a local blockade of inhibition and extracellular field potentials. These results suggest the possible involvement of NMDAR-independent LTP in the experience-dependent development of visual cortex.

Successful treatment with 5-fluorouracil of conjunctival intraepithelial neoplasia refractive to mitomycin-C.

PURPOSE: To describe the histopathological findings and successful treatment with 5-fluorouracil (5-FU) of a conjunctival intraepithelial neoplasia with limbal stem cell deficiency that was refractive to topical mitomycin-C (MMC). DESIGN: Interventional case report. INTERVENTION: A 64-year-old male patient presented with a diffuse conjunctival intraepithelial neoplasia (CIN) that was excised with concurrent keratoepithelioplasty. Because of a recurrence and the presence of limbal stem cell deficiency, he was placed on topical MMC. Despite two courses of MMC, the tumor size did not decrease, and topical 5-FU was started 1 year after MMC therapy began. Limbal autograft transplantation was performed thereafter. MAIN OUTCOME MEASURES: The clinical and histopathologic findings including impression cytology and biomicroscopic observations. RESULTS: After 5-FU treatment, the patient was free of the tumor clinically and cytologically, and the corneal surface had cleared. No recurrence was observed during the 30 months after the 5-FU therapy. Serious complications have not been observed. CONCLUSIONS: Topical 5-FU may be a therapeutic option for the treatment of patients with MMC-resistant CINs. The success of 5-FU is believed to be the result of a difference in the mechanism of cytotoxicity of MMC and 5-FU or the additive effects of the two agents.