Central Pain: a Neurosurgical Survey

NEUROSURGICAL SURVEY. By Valentino Cassinari and Carlo A. Pagni. (Pp. xi+ 192. 63s). Harvard University Press (Dist. in Great Britain by Oxford University Press, London), 1969. THIS book is a synopsis of world literature and personal experience of the authors in the problems of physiopathogenesis and treatment of central pain. The opening chapter reviews knowledge and theories concerning the pathways for pain in the spinal cord and brain, with diagrams. Central pain of spontaneous origin is discussed in brief, but the authors conclude that little of value can be learned from a study of spontaneous lesions such as tumors, vascular mishaps, disseminated sclerosis and syringomyelia, because of the grossness of such lesions. Studied in much greater detail, and occupying onethird of the survey, are the surgical operations that have given rise to central pain. Some of these operations have been performed for non-painful conditions such as extrapyramidal syndromes, tumours, encephalopathy of children, spastic syndromes, etc., but most of them have been neurosurgical operations performed for relief of pain of presumed non-central type. These operations have been at various levels and include thoracic and cervical antero-lateral cordotomy (often resulting in a substitution of central pain and discomfort for the original pain), commissural myelotomy and tractotomies at various levels. The latter have produced central pain and unpleasant paraesthesias, the open operations considerably more frequently than the stereotactic procedures. Other operations discussed are posterior cordotomy, parietal lobectomy, hemispherectomy, various leucotomies, pyramidotomies and extra-pyramidotomies. There is no mention except briefly "chemical radicotomy, now being tried out experimentally" of phenol peri-ganglion injection for trigeminal neuralgia, or intrathecal injection for limb and trunk intractable pain, although these methods have been in use in a few centres for over a decade. There is a discussion on theories which attempt to explain the onset of central pain, such as loss of a specific thalamic function, release phenomena, irritation of sensory pathways and centres (elaborated and supported later on in the book), central sympathetic or hypothalamic disturbance, etc. The situation and character of sensory disturbance in relation to the level of the lesion in the central nervous system is discussed. The large number of surgical operations which have been and are in use in the attempted relief of central pain is a measure of the unsatisfactory results obtained, and, although some successes arc claimed for most of the operations, results are unpredictable and inconstant, and relief frequently only transient. One of the conclusions reached in the final chapter is that the various surgical operations have substantially contributed to our knowledge of the anatomicopathological pathways for central pain, for instance, that data from thousands of cases all over the world have shown unequivocally that in stereotactic surgery on the thalamus, lesions which spare the sensory relay nuclei never give rise to central pain, whatever part of the thalamus. or however much of its diffuse projection system, is destroyed. Another firm conclusion reached was that a lesion along the spinothalamicocortical pathwav is necessary to produce central pain, and it is immaterial at what level or how complete this lesion is. The authors pronounce a warning to neurosurgeons that, if their theoretical premises are valid, it is impossible with the classic operations for pain syndromes spinal cord, bulbar and mesencephalic tractotomy, and stereotactic surgery aimed at the ventro-posterior medial and lateral nuclei of the thalamus for the surgeon to rule out the risk of production of central pain, and this risk should not be concealed from the patient. The authors append a summary of eight of their personally operated cases. Although no doubt intended for the specialist, this book compresses a wide area into a small dimension and could be read with benefit by any doctor interested in the problem of pain, and even by the undergraduate who is interested in the clinical implications of neuro-anatomy. G.A.G.