Syphilis was once the most common cause of aortic aneurysm. For the last 60 years syphilis has been well controlled in the UK population. However, we present the recent case of a 52-year-old female black South African immigrant who was found to have a syphilitic aneurysm.

In animal models of Parkinson's disease and in human patients, where dopamine cells in the substantia nigra (SN) are depleted, the mean firing rate of neurons in the subthalamic nucleus (STN) is increased. As these neurons send excitatory, glutamatergic projections to SN, it is possible that this overactivity may result in excitotoxicity, leading to further dopamine cell loss. Lesions of the STN can be neuroprotective against the dopamine cell loss caused by injections of 6-hydroxydopamine into the rat striatum. However, it has not been shown whether STN overactivity can directly cause dopamine cell death. To address this question ibotenic acid lesions were made in the rat globus pallidus, a manipulation that has been shown to increase the firing rate of STN neurons. Three weeks later a significant increase in microglial activity and astrocytic activation in the SN ipsilateral to the lesion was observed, whilst unbiased stereological counting showed the number of dopamine neurons to be reduced by 15%. By 6 weeks after the lesion there was a reduction of dopamine cells of more than 30% ipsilaterally but now contralateral to the lesion dopamine cells were also reduced by 20%. This loss of dopamine cells in the SN after a globus pallidus lesion is suggested to be due to excitotoxicity related to the increased firing of STN neurons.