Evaluation of Surgical and Spontaneous Cerebrospinal Fluid Shunts by Isotope Scanning

Abstract

S URGICAL cerebrospinal fluid (CSF) shunts are f requent ly used to t rea t some types of hydrocephalus and increased int racrania l pressure, s,2~ Rarely , vent r iculo-subarachnoid shunts (fistulas) m a y occur spontaneously . 1s,19,31,34 Ventriculovascular (ventr iculo-atr ial) and ventr iculocisternal shunts are the mos t commonly used surgical methods for short circuiting the CSF. The Nulsen-Spi tz shunt 23 with the subcutaneous Hol te r valve, and the Pudenz shunt 26 with the in t ravascular H e y e r valve are the vent r iculo-vascular devices of choice, while the Torki ldscn operat ion 35-3~ is still the preferred procedure for cisternal shunting. The question of ca the te r pa t ency and function f requent ly arises following establ ishment of a CSF shunt . Obstruct ions m a y occur a t the proximal (vcntricular) or distal (vascular or cisternal) end or in the midportion of a shunt. Occasionally d isplacement of the tubing or fo rmat ion of a cyst m a y block CSF flow. A va r i e ty of mechanical , dye, pneumo-radiographic and isotope tests are available to detect a b lock (Table 1). Tests using palpat ion, 5,23,25 fluid wi thdrawal 24 or pressure measuremen t s ~5 have been proposed. In analogy with D a n d y ' s and Blackfan 's dye studies of hydrocephalus 6,7 phenosulphophthalein has been used by Fincher et al. to s tudy the pa t ency of Torki ldsen shunts. 15 These la t te r authors have also employed pneumorad iography for the same purpose. More recently, radioisotopes have been applied to the s tudy of hydrocephalus. 1131labelled h u m a n serum a lbumin (RIHSA) has been used to s tudy normal and abnormal CSF dynamics b y sample counting, ~,32,3a external probe counting, 2'3 and scanning. 9-~4 These isotopic techniques have been extended quite na tu ra l ly to the s tudy of CSF shunts. Some shunts have been evalua ted by injecting R I H S A into the ventricles and