Negative predictive value of (123)I Ioflupane SPECT in movement disorders

A non-degenerative etiology is supported by a normal SPI [normal SPECT with 123I-Ioflupane (SPI)] in a patient with movement disorders (MD). A total of 196 SPIs were conducted during the period of 2004/05. Of these, 44 were selected in order to rule out degenerative MD (DMD), the results being normal in these patients. The clinical background of these patients were reviewed in a minimum period of 24 months (range 24-40), collecting the diagnoses reached by the neurology specialists. The SPI were evaluated using a consensus, according to subjective criteria and quantification. Thirty-six of the 44 patients (81%) were identified at 2 years of having nondegenerative movement disorders: 18 as essential tremor, 5 as drug-induced disorder, 4 as vascular disease, 3 as peripheral polyneuropathy, 2 postural tremors, 1 writer's cramp, 1 psychogenic tremor, 1 intercranial hypertension and 1 fibromyalgia. The remaining 8 patients were diagnosed with Parkinson's disease in 5 cases, 1 corticobasal degeneration, 1 multisystemic atrophy and another degenerative Parkinsonism with unclear etiology. The SPI in our hospital has a lower negative predictive value than the data reported in the literature. The false negatives could be explained because most of our patients come from neurologist physicians who are not movement disorder experts. In addition, a small proportion of degenerative Parkinsonism could evolve with normal SPI.