Evaluating the Effects of Cerebrospinal Fluid Protein Content on the Performance of Differential Pressure Valves and Antisiphon Devices Using a Novel Benchtop Shunting Model

BACKGROUNDHydrocephalus is managed by surgically implanting flow-diversion technologies such as differential pressure valves and antisiphoning devices; however, such hardware is prone to failure. Extensive research has tested them in flow-controlled settings using saline or de-aerated water, yet little has been done to validate their performance in a setting recreating physiologically relevant parameters, including intracranial pressures, cerebrospinal fluid (CSF) protein content, and body position.OBJECTIVETo more accurately chart the episodic drainage characteristics of flow-diversion technology. A gravity-driven benchtop model of flow was designed and tested continuously during weeks-long trials.METHODSUsing a hydrostatic pressure gradient as the sole driving force, interval flow rates of 6 valves were examined in parallel with various fluids. Daily trials in the upright and supine positions were run with fluid output collected from distal catheters placed at alternating heights for extended intervals.RESULTSSignificant variability in flow rates was observed, both within specific individual valves across different trials and among multiple valves of the same type. These intervalve and intravalve variabilities were greatest during supine trials and with increased protein. None of the valves showed evidence of overt obstruction during 30 d of exposure to CSF containing 5 g/L protein.CONCLUSIONDay-to-day variability of ball-in-cone differential pressure shunt valves may increase overdrainage risk. Narrow-lumen high-resistance flow control devices as tested here under similar conditions appear to achieve more consistent flow rates, suggesting their use may be advantageous, and did not demonstrate any blockage or trend of decreasing flow over the 3 wk of chronic use

Periosteal Lipoma Compressing Peripheral Nerves

Introduction: Lipoma is a common benign, slow-growing soft tissue neoplasm. Periosteal lipomas of the proximal radius causing posterior interosseus nerve (PIN) palsy are the rarest.  Due to specific anatomical relationships, proximal antebrachial lipomas can easily compress PIN. We present a case report and report on the related literature. Material and Methods: A 55-year-old female was admitted complaining of a progressively growing lump in the anterior-lateral antebrachial region near the left elbow. The recent onset of weakness in finger extension was more evident during manual work.  MRI showed a well-defined oval lesion in the dorsal aspect of the proximal radius bone with inter-muscular laying between m. supinator et extensor carpi radialis brevis of 7x5x3 cm in diameter. EMG study confirmed PIN compression syndrome. An en-block extirpation was performed through extensor muscles. PIN and its muscular branches were well preserved. Histological examination confirmed lipoma. The postoperative course was uneventful, and a good recovery was seen within 12 days.  We revised three other similar cases operated for the same Clinical diagnosis by our team.  Pertinent literature was reported.  Discussion: Periosteal radius lipoma related to compression of PIN has rarely been reported in the literature. We say our operative series and the surgical technique. MRI and EMG are the standard diagnostic methods. The intermuscular approach is safe for total tumor removal in experienced hands. Conclusion: Periosteal lipoma compressing PIN is a rare clinical finding. Total removal may be obtained through an intermuscular approach. Intraoperative monitoring can assist in preserving tiny PIN branche