ABSTRACT
A 65-year-old man presented with headache, altered mental status, and somnolence. The patient had a ventriculoperitoneal (VP) shunt revised a month earlier. A CT of the head was performed, which demonstrated interval development of hydrocephalus compared with the prior examination done at the time of the shunt revision. Further evaluation of the VP shunt dynamics was obtained through a radionuclide shuntogram using 99mTcO4. The shuntogram demonstrated passage of the radiotracer down the VP shunt tubing. This case illustrates the utility of radionuclide shuntogram in demonstrating an unusual cause of hydrocephalus after VP shunt placement.
Subject(s)
Hydrocephalus/diagnostic imaging , Ventriculoperitoneal Shunt/adverse effects , Aged , Humans , Hydrocephalus/etiology , Male , Radiopharmaceuticals/cerebrospinal fluid , Sodium Pertechnetate Tc 99m/cerebrospinal fluid , Tomography, Emission-ComputedABSTRACT
Perfusion of the ventriculocisternal system in unanesthetized sheep was used to quantify the pathways by which the pertechnetate anion (TcO4-) may leave the cerebrospinal fluid space. The largest fraction (about 89%) was removed from the fluid before it reached the cisterna magna; this extraction was significantly inhibited by iodide ion in the perfusion fluid. One-fifth of the extracted pertechnetate remained in the head of the animal for over 3 hours. Only about 3% of the infused pertechnetate was resorbed with the bulk flow of cerebrospinal fluid through the arachnoid villi. These results are consistent with the concept of a specific brain channel for removal of anions. As pertechnetate and iodide ion are thought to be transported by the same mechanisms, the physiological role of this channel may be maintenance of a very low iodide concentration in the extracellular fluid of the brain.
