The usefulness of [ 123 I]‐metaiodobenzylguanidine myocardial scintigraphy in patients with subacute myelo‐optico‐neuropathy

Background Patients with subacute myelo‐optico‐neuropathy ( SMON ), caused by clioquinol intoxication more than 40 years ago, had been suffered from various kinds of autonomic disorders, such as diarrhea, constipation, and incontinence. [ 123 I]‐metaiodobenzylguanidine ( MIBG ) myocardial scintigraphy is a sensitive test for diagnosis of Parkinson's disease ( PD ). Aim We tried to clarify the usefulness of MIBG myocardial scintigraphy in SMON patients for diagnosing PD . Methods The MIBG myocardial scintigraphy was investigated in fifteen SMON patients who were suffered from various kinds of autonomic symptoms. In these SMON patients, four patients (mean age ±  SD ; 73.3 ± 6.8) showed early stage of PD , whose Hoehn–Yahr (H–Y) stage was stage I or stage II, but the other eleven patients (mean age ±  SD ; 78.0 ± 7.6) had not any signs or symptoms of Parkinsonism. Results Four patients with early stages of PD showed significantly reduced MIBG uptake. Eleven patients except one without Parkinsonism showed normal MIBG uptake. No apparent relation between the degree of the autonomic symptoms and the MIBG uptake was observed. One patient without Parkinsonism showed significantly reduced MIBG uptake and was suggested to be suffered from a preclinical state of PD , since the [ 123 I]‐ioflupane single‐photon emission computed tomography scintigraphy showed decreased uptake of isotopes in the bilateral striate regions 8 years after the MIBG myocardial scintigraphy. Conclusion The MIBG myocardial scintigraphy in SMON patients with various kinds of autonomic symptoms is useful as a highly sensitive and specific tool for diagnosing PD .