P. F. Munari

The persistent primitive hypoglossal artery: A rare anatomic variation with frequent clinical implications

The case of a persistent primitive hypoglossal artery (PHA) in a 72-year-old man dead from myocardial infarction is presented. The autopsy showed the presence of a semicircular marginal infarct on the surface of the left cerebral hemisphere. The PHA anastomized the basilar artery origin with the left internal carotid artery, running through the left hypoglossal canal together with the hypoglossal nerve. The vertebral and posterior communicating arteries were hypoplastic. The PHA represented the morphological base on which the cerebral vascular insufficiency acted, following the generalized circulatory insufficiency due to the myocardial infarct, causing the cerebral infarct. Based on the embryology of the cranial arteries and on the morphological findings we suggest that the persistence of the hypoglossal artery: 1) precedes the vertebral and posterior communicating arteries hypoplasia causing it by competition for the territory of distribution; 2) gives rise to an almost complete dependence of the cerebral circulation from the carotid system with predictable ischemic consequences in the case of a critical reduction of the carotid blood flow; 3) may be associated with an anomalous structure of the vessel wall and exposes the basilar trunk to an unusual haemodynamic stress, predisposing to the onset of aneurysms.

FENESTRATION OF THE VERTEBROBASILAR JUNCTION

SummaryA fenestration of the vertebrobasilar junction was found in an 80-year-old man during autopsy. It was associated with thrombosis of the vertebral arteries which had caused a left Wallenberg syndrome. The left limb of the fenestration presenting the same transverse diameter as that of the remaining part of the basilar artery appeared to be its direct (true) origin. The right limb had a lesser transverse diameter and appeared to bridge the lateral surface of the rostral end of the right vertebral artery and the basilar trunk. According to the authors, this fenestration could have been caused by the persistence of the cranial part of a primitive lateral vertebrobasilar anastomosis, rather then by the usual incomplete fusion of the primitive paired basilar arteries.

Congenital Polyp of the Prostatic Urethra: Report on 2 Cases

Congenital polyps of the prostatic urethra are an uncommon cause of obstructive uropathy, infection and/or hematuria in male children. A filling defect localized in the posterior urethra on the voiding cystourethrogram represents the peculiar diagnostic finding. Transurethral resection is the treatment of choice, according to the size of the polyp. Two cases of congenital posterior urethral polyps are reported and the main clinical and radiological features are discussed. This lesion has to be considered in the differential diagnosis of the voiding dysfunction in young boys.

Anatomical basis of hypoxic and hyperoxic injuries to the centres of cardiorespiratory regulation.

The aim of the present paper is to briefly review the changes occurring in the nucleus tractus solitarii and carotid body in response to hypoxic and hyperoxic injuries. Selective alterations of dendrites and Fos-immunoreactivity of neurons have been observed in the subnucleus gelatinosus of the nucleus tractus solitarii of adult subjects dying after hypoxic-ischaemic injury. The selective vulnerability of this portion of the nucleus tractus solitarii may be explained mainly with reference to the vascularization of medullary tegmentum. In the carotid body, chronic hypoxia and hyperoxia cause a series of morphological, cellular and biochemical changes which may play a major role during the first postnatal period and may have implications in the pathogenesis of Sudden Infant Death Syndrome. Intermittent hypoxia may cause hypersensitivity of the carotid body, possibly increasing the risk of unstable respiration. Conversely, hyperoxia exposure has been reported to cause hyposensitivity and reduction in volume of the carotid body, possibly leading to ineffective response.

Structural and Ultrastructural Changes in Ileal Neobladder Mucosa: A 7-Year Follow-Up

OBJECTIVE To investigate the long-term morphological changes in the intestinal segment used to create an orthotopic ileal neobladder. MATERIALS AND METHODS Periodic endoscopy with biopsy of the ileal mucosa was performed in 90 patients 3-84 months after radical cystectomy and urinary diversion via an orthotopic neobladder. Three cold-cup biopsies were taken from each patient and mucosal specimens processed for light and electronic microscopy. RESULTS Early changes (up to 1 year after surgery) comprised a marked shortening of the villi with loss of microvilli. After 4 years, the prevalent finding was of flat, avillous epithelium that tended to stratify in some areas. The avillous areas were mixed with islets of villous mucosa. There was no dysplasia or malignancy in any of the 90 patients. CONCLUSIONS Prolonged contact with urine elicited a biphasic response in the ileal mucosa, i.e. an early inflammatory phase, ascribed to the noxious action of urine, followed by a regressive phase in which the epithelium tended to assume a morphology similar to the urothelium. The atrophic changes were almost totally completed after 4 years, although areas with marked modifications alternated with others where the morphology was normal, even many years after surgery. Late changes in the ileal neobladder mucosa appear to be an expression of a functional adaptation of the mucosa to the new environment.

The bulbocerebellar circumolivary bundle

During the course of a systematic study on the human vertebrobasilar arterial system (De Caro et al. 1995), our attention was drawn in one case to a strange morphology of the ventrolateral aspect of one side of the medulla. While initially our impression was that we were facing an actual malformation, review of the structure of the brainstem as described in most standard anatomical texts showed that it could correspond to the circumolivary fasciculus (Williams et al. 1995).