November 2010
Bajaj NP, Gontu V, Birchall J,
Patterson J, Grosset DG, Lees AJ.
Objective: Driving activity requires major involvement of executive
functions. The main objective of our study was to
Background: This study examines the clinical
accuracy of movement disorder specialists in distinguishing tremor
dominant Parkinson's
disease (TDPD) from other tremulous
movement disorders by the use of standardised patient videos.
Patients and methods:
Two movement disorder specialists were asked to distinguish TDPD from
patients with atypical tremor and dystonic tremor,
who had no evidence of presynaptic
dopaminergic deficit (subjects without evidence of dopaminergic deficit
(SWEDDs)) according
to 123I-N-ω-fluoro-propyl- 2β-carbomethoxy-3β-(4-iodophenyl) nortropane ([123I]
FP-CIT) single photon emission computed tomography (SPECT), by
‘blinded’ video analysis in 38 patients. A diagnosis of parkinsonism was
made if the step 1 criteria of the Queen Square Brain Bank criteria for
Parkinson's disease were fulfilled. The reviewer diagnosis was compared
with the working clinical diagnosis drawn from the medical history,
SPECT scan result, long term follow-up and in some cases the known
response to dopaminergic medications. This comparison allowed a
calculation for false positive and false negative rate of diagnosis of
PD.
Results: High
false positive (17.4-26.1%) and negative (6.7-20%) rates were found for
the diagnosis of PD. The diagnostic distinction
of TDPD from dystonic tremor was
reduced by the presence of dystonic features in treated and untreated PD
patients.
Conclusion:
Clinical distinction of TDPD from atypical tremor, monosymptomatic rest
tremor and dystonic tremor can be difficult due to
the presence of parkinsonian features
in tremulous SWEDD patients. The diagnosis of bradykinesia was
particularly challenging.
This study highlights the difficulty of
differentiation of some cases of SWEDD from PD.
