The Movement Disorder Society

MDS Abstract of the 16th International Congress of Parkinson's Disease and Movement Disorders, Volume 27,
June 2012 Abstract Supplement

Movement Disorders 2012
Dublin, Ireland June 17-21, 2012.


Stiff person syndrome: Abnormalities of D2 receptor imaging

Balint,  B., Haberkorn,  U., Kratochwil,  C., Meinck,  H.M.

Objective:

To investigate patients with Stiff Person Syndrome (SPS) for disturbances of dopaminergic transmission.

Background:

SPS is a rare disorder characterized by progressive fluctuating rigidity of trunk and proximal limb muscles superimposed by painful spasms. Apart from mere motor symptoms, patients are often handicapped by a characteristic fear of walking unaided which is best described as task-specific phobia and might precede onset of motor symptoms. Furthermore, many patients complain of episodes resembling gait ignition failure, or freezing of gait (FOG). As the latter are frequently encountered in parkinsonian syndromes, this raised the question of disturbances of dopaminergic neurotransmission in SPS.

Methods:

We investigated 19 patients with the clinical, immunologic, neurophysiologic and neuropharmacological characteristics of SPS. Two patients had a striatal toe; none had bradykinesia or tremor. Duration of motor symptoms ranged between 1m-44 y. All patients had normal MRI scans of brain and spinal cord. We performed dopamine D2 receptor imaging by means of 123I-benzamide (IBZM-) SPECT. Regions of interest (ROIs) were delineated on transaxial slices, and counts/pixel in the putamen and caudate nucleus were compared with the whole cerebral cortex as the reference region. In normal controls, such ratios exceed 1.46. Ratios between 1.40 and 1.45 were considered subnormal, and ratios below 1.40 as abnormal.

Results:

Dopamine receptor imaging revealed a reduced radiotracer uptake in the putamen and caudate nucleus in all patients. Radiotracer uptake reduction did not correlate to clinical symptoms, disease duration, antibody status or to a particular drug treatment.

Conclusions:

The data suggest that neurotransmission in SPS is disturbed in a more complex fashion than assumed so far. The dopamine receptor labelling indicates reduced receptor binding capacity possibly due to functional down-regulation, loss of dopamine receptors, or a loss of neurones with dopamine receptors on their surface. As to clinical implications, however, abnormalities in IBZM-SPECT imagining in patients with complex gait disturbances like FOG do not necessarily suggest atypical parkinsonism, but might also occur in SPS.

Keywords :

Basal ganglia,Dopamine receptor,Single-photon emission computed tomography(SPECT),Stiff-person syndrome

To cite this abstract, please use the following information:
Balint, B., Haberkorn, U., Kratochwil, C., Meinck, H.M.; Stiff person syndrome: Abnormalities of D2 receptor imaging [abstract]. Movement Disorders 2012;27 Suppl 1 :695