[Effect of magnetic fields from home-use magnetic induction therapy apparatuses on adjustable cerebrospinal fluid shunt valves].

OBJECTIVE: Cerebrospinal fluid (CSF) shunts are frequently used to treat hydrocephalus. The use of a programmable valve allows the operator to easily change the opening pressure. In Japan, many people use magnetic induction therapy apparatuses in their homes. However, exposing patients with adjustable CSF shunt valves to the permanent magnets included in these apparatuses may alter the shunt valve's programmed settings or permanently damage the device. Therefore, the goal of this study was to determine the health risk associated with magnetic induction therapy for patients using programmable CSF shunt valves. METHODS: Five models of shunt valves from five different manufacturers, the Miethke proGAV (proGAV), the Codman Hakim programmable valve (CHPV), Sophysa Sophy model SM8 (Sophy valve), Sophysa Polaris model SPV (Polaris valve), and Strata II valve (Strata valve) were evaluated in this study. Magnetic field interactions were determined for the programmable valves by using magnetic stones with various magnetic flux densities. The maximum distance between the valve and the magnetic stone affecting the valve pressure setting was measured by X-ray. RESULTS: The proGAV and Polaris valve were immune to unintentional reprogramming by the magnetic stones. The CHPV, Sophy valve and Strata valve, however, randomly changed settings by magnetic stones. CONCLUSIONS: Whereas the CHPV, Sophy valve and Strata valve were promptly reset by exposure to a magnetic stone with a similar strength to that used in magnetic induction therapy, proGAV and Polaris valve were resistant to inadvertent reprogramming when exposed to magnets up to 190 mT.

[Case of reversible posterior leukoencephalopathy syndrome after discontinuation of antihypertensive therapy].

A 36-year-old man who was poorly compliant with his antihypertensive medication regimen was admitted to our hospital because he had nausea and an altered mental status. His disorientation increased on admission. His blood pressure was 219/156 mmHg. No focal neurologic deficits were detected, but a cranial computed tomography (CT) performed on admission revealed a low-density area in the brainstem region. Subsequent cranial T2-weighted and fluid-attenuated inversion-recovery (FLAIR) magnetic resonance imaging (MRI) performed on the same day revealed high-intensity areas in the brainstem, bilateral cerebellar hemisphere, bilateral occipito-temporal subcortical white matter, right thalamus, and the right basal ganglia region. Diffusion-weighted MRI revealed that the edema was of vasogenic origin and was not indicative of ischemia/infarction. Biochemical testing revealed a blood urea nitrogen level of 35.7 mg/dL, a serum creatinine level of 3.27 mg/dL, proteinurea (4.6 g/24 hours), and a glomerular filtration rate of 47. 6 mL/min/1.83 m2. These findings suggested a diagnosis of chronic kidney disease (CKD). The patient was diagnosed with hypertensive encephalopathy, and treatment with intravenous diltiazem was initiated. The clinical symptoms resolved 3 days after admission, and the abnormal findings in CT and MRI demonstrated completely resolved 44 days after admission. This was a rare case of reversible posterior leukoencephalopathy syndrome (RPLS) that was caused by severe hypertension and was aggravated by discontinuation of antihypertensive therapy. RPLS was caused by vasogenic edema because of sudden elevations in systemic blood pressure which exceed the autoregulatory capacity of the brain vasculature.