Impaired dopamine transmission in common
A small percentage of people with HSP exhibit symptoms of Parkinson’s disease. This research demonstrates what they share in common is impaired dopamine transmission in a pathway in the brain associated with motor control (the nigrostriatal dopaminergic system).
Sporadic spastic paraplegia (SSP) and hereditary spastic paraplegia (HSP) belong to a clinical and genetically heterogeneous group of disorders characterized by progressive spasticity and weakness in the lower extremities. The symptoms are associated with pyramidal tract dysfunction and degeneration of the corticospinal tracts.
Parkinsonism is uncommon in SSP/HSP patients. However, both disorders are associated with damage to the nigrostriatal dopaminergic system. In the present study, the clinical features of patients with SSP/HSP were investigated, and nigrostriatal dopaminergic binding potential was assessed using dopamine transporter (DAT) single-photon emission computer tomography (SPECT).
Nine patients with spastic paraplegia participated in the present study. The subjects underwent DAT SPECT using the agent [2-[[2-[[[3-(4-chlorophenyl)-8-methyl-8-azabicyclo[3,2,1]oct-2-yl]methyl](2-mercaptoethyl)amino]ethyl]amino]ethanethiolato (3-)-N2,N20,S2,S20]oxo-[IR-(exo-exo)])-[(99)mTc]technetium ([(99)mTc]TRODAT-1). The [(99)mTc]TRODAT-1 SPECT images of five patients appeared normal, whereas the images of four patients revealed reduced striatal ligand uptake. Among the four patients with reduced uptake, two had parkinsonism, and one exhibited periodic limb movements and restless leg syndrome.
Our DAT SPECT imaging study shows that reduced DAT density may be observed in patients with parkinsonism. The results of the present study offer an explanation for the spectrum of spastic paraplegia symptoms and the progression of the disorder.
SOURCE: J Korean Med Sci. 2013 Nov;28(11):1661-6. doi: 10.3346/jkms.2013.28.11.1661. Epub 2013 Oct 31. PMID: 24265532 [PubMed – in process] PMCID: PMC3835511
Striatal dopaminergic functioning in patients with sporadic and hereditary spastic paraplegias with parkinsonism.
Kim JS1, Kim JM, Kim YK, Kim SE, Yun JY, Jeon BS.
1Department of Neurology, College of Medicine, Chungbuk National University Hospital, Cheongju, Korea.