Hydrocephalus Shunts

The hydrocephalus shunt is a relatively simple device that can be implanted for long time periods into the subarachnoid region of the head it serves to drain away excess cerebrospinal fluid that... 

PDMS) Catheters Drug dehvery devices Heart valves Hydrocephalus shunts Membrane oxygenators... 

Poly(tetrafluoroethylene) (PTFE) Heart valves Vascular grafts Facial prostheses Hydrocephalus shunts Membrane oxygenators Catheters Sutures... 

Starting with the silicone elastomer hydrocephalus shunt in 1955, silicone elastomer has become widely used as a soft, flexible, elastomeric material of construction for artificial organs and implants for the human body. When prepared with controls to assure its duplication and freedom from contamination, specific formulations have excellent biocompatibility, biodurability, and a long history of clinical safety. Properties can be varied to meet the needs in many different implant applications. Silicone elastomer can be fabricated in a wide variety of forms and shapes by most all of the techniques used to fabricate thermosetting elastomers. Radiopacity can be increased by fillers such as barium sulfate or powdered metals. It can be sterilized by ethylene oxide, steam autoclave, dry heat, or radiation. Shelf-life at ambient conditions is indefinite. When implanted the host reaction is typically limited to encapsulation of... 

Holter s successful development of a silicone elastomer hydrocephalus shunt (4) (Figures 1-2) in 1955 heralded the era of implants. No effective treatment for hydrocephalus was known at the time. Thus, by 1957, only two years after the shunt was first used, and continuing today, essentially every hydrocephalic child born in the developed countries of the world has received a silicone elastomer hydrocephalus shunt implant. Hydrocephalus occurs in approximately one out of every 400 to 600 children born alive. The hydrocephalus shunt is one of the oldest, and also one of the most widely used of all silicone elastomer implants. Some individuals have now had shunt implants for more than 25 years. The excellent biocompatibility of implant grades of silicone elastomer is evidenced by the essential absence of adverse biological response in this long term, large volume use. 

Figure 1. A silicone elastomer hydrocephalus shunt. This type of shunt is used to drain cerebrospinal fluid from the ventricle of the brain to either the vascular system or to the peritoneal cavity. The first hydrocephalus shunt was developed by Hoi ter in 1955. The shunt in this illustration contains a dual flushing chamber to assure continual function of the shunt, and is designed to drain cerebral spinal fluid from the ventricle of the brain to the peritoneal cavity.

Heart Assist Devices Heart Valves Hydrocephalus Shunts Immobilized Enzymes Implantable Pumps Inner Ear Repairs Joint Replacement Pacemakers Plasma Extenders Plastic Surgery Polymeric Drugs Polymeric Food Additives Pseudoenzymes Reinforcing Mesh Replacement Blood Vessels Replacement Skin Soft Tissue Replacement Surgical Adhesives Surgical Tape Sutures... 

The first documented use of sUicone as biomaterial was silicone mbber tubing as shunts for treatment of hydrocephalus in about 1955. From 1960 to 1990, the biomedical application of sUicone mbber was steadUy grown. One of the most well-known silicone product is the Norplant contraceptive implant. The first clinical experiment with this device was reported in 1966. FDA approved its use in 1990. 

Identification of patients with adult-onset hydrocephalus that will respond to a ventriculoperitoneal shunt is challenging. Criteria have been established, but the rate of response remains low (Boon et al., 2000 Kahlon et al., 2005 Marmarou et al.,... 

A 9-year-old child with a repaired myelomeningocele and congenital hydrocephalus who had undergone four previous shunt revisions in the past had two episodes of anaphylaxis during insertion of the ventriculoperitoneal shunt. The shunt tubing had been soaked in a solution of bacitracin 2500 U/ml. A skin prick test was positive for bacitracin. 

A 66-year-old man with neurocysticercosis treated with glucocorticoids and praziquantel developed headache and confusion. He did not have a ventricular shunt inserted. A contrast-enhanced CT scan showed multiple focal enhancing lesions with mild edema. An MRI scan of the head was reported as being most consistent with neurocysticercosis. He was given dexamethasone 2 mg bd and praziquantel 50 mg/kg/day. A few days later his headache worsened, with nausea and drowsiness. After 2 weeks he became stuporose and had to be ventilated. A CT scan showed multiple areas of deep subcortical focal edema near the areas of previously enhancing cysts, a striatocapsular stroke, and obstructive hydrocephalus. Two weeks after the last dose of praziquantel and despite a ventriculostomy tube he died. 

Primary peritonitis in adults occurs most commonly in association with alcoholic cirrhosis, especially in its end stage, or with ascites caused by postnecrotic cirrhosis, chronic active hepatitis, acute viral hepatitis, congestive heart failure, malignancy, systemic lupus erythematosus, or nephritic syndrome. It also may result from the use of a peritoneal catheter for dialysis or central nervous system ventriculoperitoneal shunting for hydrocephalus. Rarely, primary peritonitis occurs without apparent underlying disease. 

Fluid transfer implants are required for cases such as hydrocephalus, urinary incontinence, glaucoma-related elevated intraocular pressure, and chronic ear infection. Ffydrocephalus, caused by abnormally high pressure of the cerebrospinal fluid in the brain, can be treated by draining the fluid (essentially an ultrafiltrate of blood) through a cannula. Earlier shunts had two one-way valves at either end. However, the more recent Ames shunt has simple slits at the discharging end, which opens when enough fluid... 

A standardized protocol for the evaluation of the urinary tract must be established in every radiological department caring for neonates, infants and children with myelodysplasia. Such a protocol might be as follows After the myelomeningocele has been repaired and the hydrocephalus has been relieved by a shunt device, ultrasound studies of the kidneys and the bladder should be performed. During the first 6 weeks of life, a video-urodynamic study, if available, or a modified VCU study must be performed. In hospitals where only urodynamics is available, we suggest a modified VCU study as well. 

Cerebrospinal fluid flow Phase contrast methods have been used to measure velocity and volume flow rates of cerebrospinal fluid in healthy volunteers and in patients with various diseases. This method can be used to measure the flow rate of cerebrospinal fluid through ventriculo-peritoneal shunts in patients with hydrocephalus (Figure 4). 

---