Objective: To evaluate the combination of spinal tap test (STT) with cerebral perfusion measurement assessed either by Tc-bicisate-SPECT (Tc-SPECT) or perfusion-weighted MRI (pwMRI), or both, for a better preoperative selection of candidates for shunt operations in patients with gait disorders who were suspected for having a normal pressure hydrocephalus.
Methods: Twenty-seven consecutive patients were examined with a standard clinical protocol (assessed by a walking test and the Homburg-Hydrocephalus-Scale (HHS)) as well as with 99m-Tc-bicisate-SPECT (n ϭ 27) or additionally by pwMRI (n ϭ 12) before and after STT. The results of these examinations were compared preoperatively for each patient and correlated with postoperative clinical outcome after shunt surgery.
Results: Nine patients showed both, a clinical improvement and increased cerebral perfusion after STT. They underwent shunt surgery with good to excellent results. in another nine patients, increasing cerebral perfusion was detected althuogh they did not show a clear clinical improvement after STT. Six of them also received a shunt operation with good to excellent outcome. Three patients of the last group could have an operation. Nine patients did not show any clinical improvement or any kind of increasing cerebral perfusion after STT. Therefore, they did not undergo surgery. The results of SPECT and pwMRI correlated in 92% of the patients (11 of 12).
Conclusion: It is concluded that a combination of clinical assessment with SPECT or pwMRI is helpful in the preoperative selection of patients for shunting procedures with suspected NPH syndrome (with symptoms like gait disorders, urinary incontinence and mnestic deficit). This combination is a minimal invasive and objective test modality that is superior to STT, alone. Further studies are necessary for a comparison of the described imaging techniques with different diagnostic tests in this difficult field of cerebral disease and movement disorder.