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Alastair Compston, From the Archives, Brain, Volume 129, Issue 5, May 2006, Pages 1078–1080, https://doi.org/10.1093/brain/awl086
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Some observations on the cerebral veins. By J. E. A. O'Connell. Department of Anatomy, St Bartholomew's Hospital Medical School, London. Brain 1934: 57; 484–503.
John O'Connell (1906–2001) writes from the Department of Anatomy at St Bartholomew's Hospital, London, 3 years after qualifying in medicine in 1931, on the developmental anatomy of the cortical veins and sinuses. The work was carried out at the suggestion of Professor (Herbert Henry) Woollard (1889–1939: Professor of anatomy at St Bartholomew's Hospital, 1929–36). O'Connell's anatomical observations are illustrated by Miss Z. M. Stead. Later, O'Connell was to use this knowledge of embryology to explain abnormal anatomy, in suggesting that craniopagus twins can be classified as partial—where the union is of limited extent—or total—a situationin which two brains lie within a single cranium (J. E. A. O'Connell. Craniopagus twins: surgical anatomy and embryology and their implications. Journal of Neurology Neurosurgery and Psychiatry 1976; 39: 1–22). The partial cases represent localized fusion of the cranium and brain coverings but not of deeper structures. The prospect for separation is good. The total cases are more problematic. Essentially, two heads lie within one deformed skull and several structures, notably the circulation, are shared. Whilst the arterial supplies do not anastomose, a single circular venous sinus commonly lies at the point of fusion with drainage from one twin to the transverse sinus of the other, and vice versa. It is in the attempt to reconcile this situation that, as often as not, vascular catastrophes intervene and usually prove fatal for one of the twins. Indeed, by 1976, O'Connell had reached the conclusion that one twin is bound not to survive separation of total craniopagus owing to the venous infarction imposed on one partner in securing an autonomous vascular circulation for the other.
