This site welcomes original publications, review articles, case records in the field of neurology, psychiatry, neuroradiology, neuropathology, and neurosurgery
The author: Professor Yasser Metwally
http://yassermetwally.com
INTRODUCTION
May 18, 2012 — An interesting textbook in neuroimaging created by the author. The software preferably run on computers with windows Vista or Windows 7 with at least 1 MB of RAM. Adobe reader must be preinstalled in the system.
Click here to download the software version of the textbook (18 MB) (Server 1)
Click here to download the software version of the textbook (18 MB) (Server 2)
Click here to download a different software version of the textbook (Server 1) (40 MB)
Click here to download a different software version of the textbook (Server 2) (40 MB)
Click to download the PDF version of the publication
May 14, 2012 — The neurology bulletin is a monthly digital monograph that covers a single topic in the field of neurology, psychiatry and neurosurgery. Around 40 issues are available tell now
Click here to inspect and download the issues. Simply click on any issue to download.
Click here to download all issues of the neurology bulletin in a single zip file (100 MB)
May 13, 2012 — An interesting textbook in neuroimaging created by the author. The software preferably run on computers with windows Vista or Windows 7 with at least 1 MB of RAM. Adobe reader must be preinstalled in the system.
The textbook contains 403 pages with almost 500 figures. The book is originally in PDF format. The textbook is suitable for beginner in neurology, neurosurgery and neuroradiology. It is a free textbook that can be used and distributed free of charge.
March 11, 2012 — Pituitary necrosis in patients kept alive on mechanical respirator was first described by McCormick and Halmi in 1970 (7). Subsequently several authors reported an increased incidence of pituitary necrosis in artificially ventilated patients (2,10). The incidence of pituitary necrosis which can be called respirator pituitary in patients maintained on respirators is 18-30% compared with 1-5% found in unselected autopsy material (2,6). The lesion is characterized by areas of necrosis of variable extent and can be regarded morphologically as ischemic infarct. It involves the central portion of the adenohypophysis leaving a rim of surviving parenchyma at the periphery underneath the fibrous capsule (2). The extent of necrosis varies from focal detachment of cells from the basement membrane to small or large infarcts involving up to 90 % of the adenohypophysis (2,7). Depending on the duration of artificial ventilation, the lesion may represent acute coagulating necrosis or a more chronic lesion such as capillary rich, loose connective tissue or a scar. Necrosis of the neurohypophysis may also occur in 3-40% of the cases (2,7). In many cases brain injury such as softening, swelling, infarcts of various sizes can also be demonstrated. For the cerebral lesion the term respirator brain was applied (7). However, no close correlation exists in the incidence and extent of cerebral and pituitary lesions (6,7).
The pathogenesis of pituitary infarction in patients on a mechanical respirator is not clear. Based on the morphologic findings it is evident that the lesion in the adenohypophysis is due to ischemia (3,6). Histologically identical infarcts have been found in several other conditions, such as obstetric shock, epidemic hemorrhagic fever, diabetes mellitus and section of the pituitary stalk (3,4,5,8,11). The arrest of blood flow to the adenohypophysis may be caused by vasospasm (2) or thrombosis (10) of the vessels supplying the adenohypophysis with blood. Increased intracranial pressure, severe hypotension may interfere with adenohypophysial blood flow and lead to ischemic infarction (7). The artificial ventilation per se cannot be implicated in the pathogenesis. The role of artificial ventilation is that this intervention prolongs the life of the patient and permits the progression of the lesion to histologically recognizable infarction (6). The question arises whether massive destruction of adenohypophysial cells leads to life threatening hypopituitarism. The pituitary has a remarkable reserve capacity. Previous studies showed that at least 80-90% of the pituitary parenchyma has to be removed or destroyed before symptoms of hypopituitarism may develop (3). Since adenohypophysial cells are not capable of adequate regeneration and the proliferation rate of adenohypophysial cells are very low, in patients with massive loss of hormone producing cells, normal endocrine function cannot be restored. Barber evaluated adenohypophysial function in 50 patients on mechanical respirators and found 7 cases (14%) who developed hypopituitarism (1). In his cases, hypopituitarism was transient and did not appear to affect survival. Sugimoto et al found decreased blood levels of ACTH, GH, PRL, TSH, LH and vasopressin in ventilated patients with necrosis of the hypothalamus and pituitary (9). Patients with postpartum pituitary necrosis may develop permanent hypopituitarism which, if not treated, may cause severe endocrine abnormalities and demise of the patients (8). In our case endocrinologic investigation was not performed, but it is known that patients kept alive on mechanical respirators may develop hypopituitarism (1). In these patients investigation of pituitary function should be carried out and if needed substitution therapy should be introduced.
References
Barber SG (1979) Hypopituitarism and artificial ventilation. Acta Endocrinologica 90: 211-216.
February 22, 2012 — Neurofibromatosis type 1, described by von Recklinghausen in 1882, is the most common of all the phakomatoses with a reported incidence of 1 in 3000 to 5000 in the general population. It is not a single entity but is actually a group of heterogeneous diseases affecting many systems (1). Well-defined clinical criteria are available for the diagnosis.
Central nervous system manifestations occur in 15% to 20% of all patients with NF-1. They include neoplasms, non-neoplastic hamartomatous lesions, skull and meningeal dysplasias, spine / cord / or nerve root lesions and vascular abnormalities. Vascular abnormalities associated with NF-1 predominantly involve the renal and gastrointestinal systems, with involvement of the cranio-cerebral vessels being relatively rare.
Among the rare cerebrovascular abnormalities found in patients with NF-1, the most common is stenosis or occlusion of the cerebral arteries, which may have an appearance like the moyamoya disease (2, 3). Cerebral aneurysms and arteriovenous fistulae are described as well, although less commonly (4). Subata et al (5) reviewed 43 cases of cerebrovascular manifestations of NF-1 and classified them into three groups: Group A, occlusive disorder only; Group B, cerebral aneurysm only; Group C, combined lesions of group A and B. Among those 43 cases, only 10 were associated with cerebral aneurysms and a female predominance was noted. In our case there were two intracranial aneurysms, one at the right middle cerebral artery bifurcation and the other at the posterior communicating artery origin from the right internal carotid artery. No vascular occlusive features were noted.
Non neoplastic brain parenchymal abnormalities are observed in nearly 80% of all patients with NF-1 (6). Multiple T2 hyperintense lesions in the brainstem, cerebellar white matter, basal ganglia, periventricular white matter and optic radiations are common. The radiologic criteria for distinguishing these lesions as ‘hamartomas’ (rather than neoplasm) are absence of mass effect, absence of vasogenic edema, absence of contrast enhancement or hemorrhage. One exception to the above imaging features is lesions in the globus pallidus. They demonstrate abnormally high signal intensity on T1 weighted images in more than half the patients who have them and often with mild mass effect (7).
These parenchymal lesions of NF-1 begin to appear at about 3 years of age, increase in number and size until 10 or 12 years and then they decrease in number and size. They are very rare in patients over the age of 20 years. Though the imaging features can resemble acute disseminated encephalomyelitis, the clinical presentation is different. In our case, multiple parenchymal T2 hyperintensities were seen in the pons, cerebral peduncle, basal ganglia and periventricular white matter. No T1 shortening was noted in the globus pallidus. No mass effect or contrast enhancement was noted either.
In conclusion, neurofibromatosis type I is a rare cause of intracranial aneurysms in children. When the typical brain parenchymal abnormalities are detected, screening with M.R angiogram is necessary to identify these rarely associated aneurysms.
References:
Elster AD: Radiologic screening in the neurocutaneous syndromes: strategies and controversies, AJNR 1992; 13 : 1078-1082.
E.Klause, J.Nekula, E.Minarikova and H.Farkova, Von Recklinghausen’s neurofibromatosis with intracranial stenosis of the internal carotid artery and orbito sphenoidal bone dysplasia. ROFO 1978 ; 129 : 250-252.
R.G.Leone, S.G.Shatzki and E.R. Wolpow, Neurofibromatosis with extensive intra cranial arterial occlusive disease. AJNR 1982 ; 3: 572-576.
Schievink WI, Piepgras DG. Cervical vertebral artery aneurysms and arteriovenous fistulae in neurofibromatosis type I; Case reports. Neurosurgery 1991; 29: 760-765.
E.Subata, H.Ohkuma and S.Suzuki, Cerebrovascular disorders associated with Von Recklinghausen’s neurofibromatosis: a case report. Neurosurgery 1988 ; 22:544-549.
Sevick RJ, Barkovich AJ, Edwards MSB et al: Evolution of white matter lesions in neurofibromatosis type 1: MR findings. AJR 1992; 159: 171-175.
Aoki S, Barkovich AJ, Nishimura K, Kjos B. Neurofibromatosis types 1 and 2: cranial MR findings. Radiology 1989; 172: 527-534.
