Reflex sympathetic dystrophy in a dog

Controversies surrounding reflex sympathetic dystrophy: a review article

The topic of reflex sympathetic dystrophy (RSD) has generated an increasingly significant volume of medical literature and controversy over the last decade. A search of PubMed, the online site of the National Library of Medicine, for papers on RSD reveals nearly 2200 articles on the topic (using algodystrophy as the search word, wherein RSD references are also included, and more older and European articles are also listed). From 1991 through 1998 inclusive there is an average of nearly 100 articles per year on the topic, which represents more than a third of all the articles referenced since 1965. In the decade of the 1980s, there is an average of 64 articles per year, 74 per year in the last half of the decade and 54 per year in the first half. Prior to the decade of the 1980s, one finds an average of 40 articles per year back to the mid-1960s. The controversy surrounding the disorder centers around the nature of the problem and whether it is a primary organic disorder or a primary psychogenic disorder associated with the accomplishment of some secondary gain. If it is the former, then clearly research should continue to determine the nature and etiology of the malfunctioning organ(s). If, on the other hand, RSD is a psychogenic disorder, then the medical community does well to focus mainly on the peripheral manifestations of the problem. In that instance, therapy should be primarily psychological and cognitive with regard to the secondary gain, and persistent organic treatments are unlikely to improve the condition in general and worsen individual cases.

Hemihyperaesthesia and hyperresponsiveness resembling central pain syndrome in a dog with a forebrain oligodendroglioma

A 4-year-old male Boxer was presented with neurological signs referable to a right forebrain lesion that was confirmed with computed tomography. Whilst characteristic signs of a unilateral forebrain lesion were observed, the dominant and striking finding was a right-sided hemisensory disturbance characterised by hyperaesthesia and hyperresponsiveness. Necropsy revealed a gelatinous mass confined to the right forebrain that was identified histologically as an oligodendroglioma. The lesion was centred on the internal capsule and involved ventral frontal and temporal lobes and the ventrolateral thalamus, including lateral and medial parts of the ventrocaudal nuclear region (ventrobasilar complex) of the thalamus. On clinical and neuroanatomical grounds, the case exhibited features in common with central pain syndrome in human patients with thalamic lesions. These included a somatosensory disorder of hyperaesthesia affecting an entire side of the head and body, behavioural manifestations consistent with spontaneous pain and a lesion involving the ventrobasilar complex. Of interest, the hemisensory abnormality was ipsilateral to the lesion, contrasting with central pain in humans, in which clinical signs are contralateral to analogous lesions. It is suggested that species-specific differences in spinal cord organisation of pain pathways, particularly the greater bilateral projection of nociceptive afferents to thalamic relay nuclei in carnivores, may account for this disparity. Notably, central pain is rare in human patients with brain tumours, even those affecting the thalamus, and this may also be the case in dogs.