AMERSHAM symposium

The opening symposium sponsored by Amersham Health tackled emerging concepts in ‘The Management of Parkinson’s Disease: from Diagnosis to Treatment’. Dr Donald Grosset, Consultant Neurologist from the Institute of Neurological Sciences in Glasgow began by outlining the model and time frame of the clinical diagnostic approach to parkinsonian disorders. He highlighted the particular difficulties in establishing a confident diagnosis in the early stages of illness when patients may present with tremor disorders either classical or atypical, with or without mild bradykinesia or other ‘soft’ signs of parkinsonism. He emphasised that in elderly patients concurrent morbidity such as cerebrovascular disease may be a significant confounder to diagnostic precision.

He then clearly demonstrated the utility of FP - CIT SPECT scanning (DATScan) of the pre synaptic dopaminergic system in improving diagnostic accuracy using illustrations from his own extensive research as well as data from a large multicentre European study of Clinically Uncertain Parkinsonian Syndromes (CUPS study). Dr Grosset showed how FP CIT SPECT scanning distinguishes presynaptic parkinsonism (most commonly Parkinson’s Disease) from mimics such as essential tremor and other atypical tremors, cerebrovascular disease and drug induced parkinsonism. DATScan also guides treatment decisions in difficult cases either by supporting the introduction and titration of dopaminergic drug therapy for patients with presynaptic deficit or by avoidance or withdrawal of dopaminergic therapy in persons with normal presynaptic function.

The following two presentations examined topical issues in the use of dopamine agonists (DAs) in PD. Dr. Graeme Macphee reviewed the recent literature and advice from the Committee on the Safety of Medicines on the occurrence of serosal fibrosis with the use of ergot-derived agonists. A recent CSM bulletin also alerted to a reported association of valvulopathy with pergolide treatment. Dr. Macphee pointed out that, due to the lack of a denominator, it is not possible to derive the actual risk from the adverse events reported but reinforced the guidance from the CSM regarding the need for patient monitoring.

He also reviewed the evidence with regard to the occurrence of excess somnolence and the more worrying Sudden Onset of Sleep Syndrome (SOOS) reported with DAs. Drowsiness is not specific to DAs being an adverse effect of all dopaminergic therapies including levodopa as well as an association with PD itself. Excess somnolence may be a particular problem during rapid dose escalation with DAs. It has been suggested that SOOS may be more common with non-ergot DAs but the evidence for this is inconclusive. Again Dr. Macphee echoed the CSM advice that patients need to be informed that they must not drive if they experienced SOOS.

Dr. David Stewart presented recent consensus guidelines from a group of UK clinicians on how best to switch from one DA to another. Reasons for switching include lack of efficacy and the occurrence of adverse events. Patients will often respond to a second DA and there is not always cross-reactivity for side effects. He emphasised the importance of good communication both with patients and with the primary care team. The role of the PD Nurse Specialist, where available, is of great importance. Most patients should be able to switch from one agonist to another overnight. A card documenting suggested dose equivalences to make the switch is now available.