Cerebral amyloid angiopathy. A review

Cerebral amyloid angiopathy (CAA) is a condition characterized by amyloid deposition in cerebral blood vessels. It occurs most frequently in association with clinical Alzheimer's disease but also occurs in some nondemented elderly people. CAA is a cause of spontaneous cerebral hemorrhage and may therefore present as a sudden unexpected death in an elderly person. The amyloid is deposited in cortical blood vessels, and on hematoxylin-eosin sections takes the form of pink hyaline thickening of arteries and arterioles, often with narrowing of the lumina. For diagnosis apple-green birefringence after Congo red staining is the most widely practiced and reliable tool. CAA-related hemorrhage may also occur in any lobe of the cerebrum close to the external surface and may occur at multiple sites and at the same or different times. CAA-related hemorrhage may occur in the setting of trauma necessitating distinction between the two and raising the question of whether it precipitated trauma or vice versa. Usually CAA-related hemorrhage is infrequent in sites where traumatic hemorrhages occur, and traumatic hemorrhages are often associated with other hemorrhages in sites typical for trauma. Five cases demonstrating many of the clinical and pathological features of CAA-related hemorrhage are presented. In two of the five cases, the hemorrhage followed trauma, suggesting that trauma as a precipitating factor for CAA-related hemorrhage may be more common than is generally recognized. CAA-associated hemorrhage should be considered in the differential diagnosis of cerebral hemorrhage in the elderly whether or not dementia is present.     

Intracranial hemorrhage observed in the cases of cervical internal carotid artery occlusion associated with moyamoya disease-like vessels]

We report on two peculiar cases of intracranial hemorrhage due to the rupture of moyamoya disease-like vessels associated with unilateral internal carotid occlusion at its origin. The first case is 44-year-old male showing intraventricular hemorrhage associated with right internal carotid occlusion. The second case is 58-year-old female presenting sub-arachnoid hemorrhage associated with left internal carotid occlusion. Although both cases showed the unique appearance of collateral flow resembling moyamoya disease, they were not classified as moyamoya disease nor unilateral Moyamoya-like state. Vascular abnormality such as cerebral aneurysm and arteriovenous malformation were not at all detected. The etiology of hemorrhage for both cases is presumed as the rupture of moyamoya disease-like vessels, however, it is unable for us to determine why the one case showed IVH, yet the other showed SAH. The two cases showed hypoperfusion of ipsilateral cerebral hemisphere on SPECT that followed by the external-internal carotid revascularization surgery in the chronic stage. Post operative study proved the improvement of the CBF reserve. Nevertheless, whether the reconstructive vascularization prevent an occurrence of rebleeding needs the longer observation and the accumulation of the resembling cases.     

Vitreous Hemorrhage

The incidence of spontaneous vitreous hemorrhage is approximately 7 cases per 100,000 population. Proliferative diabetic retinopathy (32%), retinal tear (30%), proliferative retinopathy after retinal vein occlusion (11%) and posterior vitreous detachment without retinal tear (8%) are the most common causes of spontaneous vitreous hemorrhage. Vitreous hemorrhage can be caused by the pathologic mechanisms of disruption of normal retinal vessels, bleeding from diseased retinal vessels or abnormal new vessels, and extension of hemorrhage through the retina from other sources. Hemorrhage into the vitreous gel results in rapid clot formation and is followed by slow clearance of approximately 1% per day. The cellular response to vitreous hemorrhage is unusual with regard to hemorrhage in any tissue outside the vitreous cavity and has been compared to a "low-turnover" granuloma. Unique clinicopathologic features of long-standing vitreous hemorrhage include cholesterolosis bulbi (synchysis scintillans), hemoglobin spherulosis, and vitreous cylinders. Complications of nonclearing vitreous hemorrhage are hemosiderosis bulbi and glaucoma. Ghost cell glaucoma, hemolytic glaucoma, and hemosiderotic glaucoma may result from vitreous hemorrhage. The established treatment option for nonclearing vitreous hemorrhage is pars plana vitrectomy. Experimental nonsurgical treatment options involve improvement of physiologic clearance mechanisms in order to accelerate fibrinolysis, liquefaction, hemolysis and phagocytosis.     

Handling flammable liquids

Control of hemorrhage during AVM surgery is one of the key issues to prevent NPPB. Inadequate procedures for hemostasis of feeders and drainers, so-called dilated capillaries and arteries (moja moja blood vessels) that are located on the side facing the normal brain, and inappropriate surgical strategies for intraoperative hemorrhage from these blood vessels are frequently the main cause of the difficulty in achieving hemostatic control. We conclude that it is important to aggressively reduce the occurrence of intraoperative hemorrhage and prevent or minimize the dilatation of abnormal capillaries and arteries due to inappropriate surgical procedures on the basis of the fundamental surgical strategy, i.e., feeder-->nidus-->drainer. Adequately securing the length and adequate coagulation of hemorrhagic blood vessel, employing a skillful bipolar coagulator technique aimed at controlling intraluminal pressure and blood flow on the central side, are believed to be key factors in hemorrhage treatment.     

Eosinophilic proliferative pylephlebitis in the liver of Japanese beef cattle with fascioliasis

Intrahepatic pylephlebitis was detected in 17 Japanese beef cattle. Grossly, the intrahepatic vessels in the caudate lobe and/or in the periphery of the other hepatic lobes were thickened and protruded above the lobar surface. The vessel lumina were packed with white to red, waste thread-like contents. A few immature flukes were found in the bile ducts in 3 of the 7 cases with biliary thickening. Foci of hepatic necrosis and hemorrhage were scattered around the thickened vessels in 8 cases. Histologically, the interlobular veins were thickened due to severe intimal hyperplasia with endothelial proliferation and eosinophilic accumulation and medial hypertrophy, accompanied by fibrosis and eosinophilic infiltration in the portal areas. Hepatic tissues with necrosis and hemorrhage were surrounded by eosinophils and histiocytes including a granulomatous reaction. One immature fluke was detected in one of these regions of necrosis. Immunoperoxidase staining revealed that the small fluke, Kupffer cells, and histiocytes in the liver of all cases were positively stained with anti-Japanese Fasciola sp. antiserum. Enzyme-linked immunosorbent assay of the sera of 15 cases revealed that all were positive for the anti-Fasciola antibody. On the basis of these findings, the present cases were regarded as an atypical form of fascioliasis, characterized by eosinophilic proliferative pylephlebitis of the liver.     

Carotid rupture and intraplaque hemorrhage: immunophenotype and role of cells involved

BACKGROUND: A complete immunohistochemical characterization in complicated carotid plaques is still lacking. The cellular components of 165 carotid endarterectomy specimens were analyzed to assess their role in the pathogenesis of plaque rupture and intraplaque hemorrhage without rupture. METHODS AND RESULTS: The fibrous caps at the sites of plaque rupture showed CD68+ macrophages, T-lymphocytes, and scarce B-lymphocytes. Ruptured plaques showed mononuclear infiltrates in the caps, shoulders, and bases of the plaques in 85% of the cases. Only 46% of nonruptured plaques showed such infiltrates (P <.0001). Two types of lipid cores were recognized: avascular or mildly vascularized and highly vascularized. The vessels of the latter type reacted with CD31 and CD34. In 57.5% of the cases, the base and the shoulders of the plaques showed neoformed, CD34+ vessels, often surrounded by mononuclear infiltrates. Intraplaque hemorrhage without rupture had highly vascularized lipid cores in all cases. T-lymphocytes and macrophages were in close contact with neoformed vessels. CONCLUSIONS: Plaque rupture is characterized by mononuclear cell infiltration of the caps, whereas intraplaque hemorrhage without rupture is characterized by extensive vascularization of the plaque.     

Relation of granulomas to lymphatic vessels in Crohn's disease

AIMS: To examine the relation between granulomas and lymphatic vessels in Crohn's disease. METHODS: Formalin fixed, paraffin wax embedded sections were selected from surgical resection specimens from 10 cases diagnosed as Crohn's disease. The block that showed the most granulomas was selected from each case. Sections 5 microns thick were immunostained with antibodies directed against the endothelial markers factor VIII related antigen and Ulex europaeus lectin, and against the vascular wall components collagen IV and laminin. Granulomas were counted on each slide in the serosa, muscularis propria, submucosa, and mucosa. In each area granulomas were classified according to their relation to lymphatic or blood vessels. RESULTS: Overall, an average of 46.1% of granulomas (range 15.3-90.4%) was related to lymphatic vessels, with the majority of these being adjacent to the vessel, rather than in the lumen or distorting the wall. A smaller percentage (10.1%, range 2.4-25.8%) was related to blood vessels. CONCLUSIONS: A significant proportion of granulomas in Crohn's disease is associated with lymphatic vessels. Blood vessel involvement may be a secondary phenomenon, rather than the primary event.     

Aneurysm of the major vessels in neurofibromatosis

The case of a patient who presented with a ruptured aneurysm of the brachial artery and type I neurofibromatosis is presented. Angiography revealed a ruptured aneurysm of the brachial artery in the middle of the upper arm. Repair of the artery with autogenous vein grafting was impossible due to the extremely brittle brachial artery and accompanying veins. The blood supply distal to the aneurysm was secured by collaterals, and the aneurysm, including a relatively long portion of the brachial artery and veins adjacent to the aneurysm, was resected. The patient died of massive hemorrhage from the subclavian artery of the involved side 9 days postoperatively. Histological and immunohistological examinations of the tissues involved in the ruptured aneurysm were conducted. The resected brachial artery and veins were surrounded by hypertrophied tissue which tested positive for S-100 protein and negative for desmin and action. These findings suggest that the origin of the proliferating tissue was not mesodermal dysplasia, but neurofibroma occurring near or in the vessels. A ruptured aneurysm in a patient with neurofibromatosis should not be treated with reconstruction of the vessels. The treatment of choice is surgical or endovascular occlusion of the vessels involved.     

Spinal neurilemmomas and neurofibromas: central dot sign in postgadolinium MRI

The MR studies of three histologically proven spinal neurilemmomas and neurofibromas were reviewed retrospectively. There were two benign neurilemmomas (schwannomas) and one neurofibroma. The common characteristic of these cases was a central low intensity focus ("dot") seen on postcontrast T1-weighted imaging. The low intensity foci corresponded histologically to a congeries of changes including edema, microcysts, foam cells, hyalinization of blood vessels, old hemorrhage, and dystrophic calcification.     

Lupus erythematosus-like features in patients with cutaneous T-cell lymphoma

The purpose of this clinical study was to review experience in the management, and outcome of eclamptic patients at Rajavithi Hospital. Standardized treatment for all cases of eclampsia has consisted of magnesium sulfate intravenously and intramuscularly to control convulsions by means of Chesley and Tepper's regimen, intravenous hydralazine intermittently to lower diastolic blood pressure when it exceeds 110 mmHg, and initiation of delivery as soon as the patient has regained consciousness and is stable. During a ten-year period there were 167,200 deliveries and 90 eclamptic patients, yielding an incidence of eclampsia of 1 in 1,857 deliveries. There were three maternal deaths (3.3%) due to intracerebral hemorrhage. Serious adverse maternal outcomes were more frequent in women whose convulsions occurred before delivery. Excluding postpartum cases, perinatal mortality of fetuses weighing 1,000 g or more was 11.7 per cent. Magnesium sulfate is the drug of choice for treatment of eclamptic convulsions. In most situations, clinical assessment of deep tendon reflexes, respirations, and urine output is adequate to monitor maternal magnesium toxicity without the need to determine actual maternal serum magnesium levels.     

Diffuse hemorrhagic gastroenteropathy: report of a new entity

An apparently novel entity, diffuse hemorrhagic gastroenteropathy (DHG), in a 70-year-old female who had an unremitting course of chronic gastrointestinal blood loss for 3 years requiring transfusion of more than 200 units of packed red blood cells over this period is reported here. Endoscopy showed diffusely hemorrhagic mucosa in the stomach, duodenum, and small bowel. Full-thickness biopsy of the stomach and small intestine revealed luminal narrowing of capillaries and post-capillary venules within the lamina propria due to swelling and some proliferation of the endothelial cells with margination and emigration by neutrophils as well as partial occlusion of some vessels by fibrin thrombi. DHG may represent a new entity characterized by mucosal hemorrhage due to local mucosal ischemia of the gastrointestinal tract secondary to a small vessel "vasculopathy" apparently restricted to this site.     

The epidemiology of hemorrhage from the upper gastrointestinal tract in the mid-nineties--has anything changed?

BACKGROUND/AIMS: Gastrointestinal hemorrhage is a frequent medical problem and a significant cause of morbidity and mortality. The aim of this retrospective analysis, which was carried out at our institution, was to establish the causes of hemorrhage from the upper digestive tract during a 3-year period. METHODOLOGY: The retrospective study includes those patients in which urgent endoscopic investigations of the upper digestive tract were carried out between 1 January 1994 and 31 December 1996. RESULTS: 2150 patients were investigated: 797 women and 1353 men. The average age of our patients was 57 years (a 3-97 year span, SD+/-17). In 665 patients (35.8%), endoscopic investigation of the upper digestive tube revealed signs of acute hemorrhage or traces of previous hemorrhage. Endoscopic hemostasis was carried out in 577 cases (31.1%). Sequelae of ulcer disease were the cause of hemorrhage in 46.1% of investigated patients. Frequent causes of hemorrhage were also inflammatory, hemorrhagically-erosive changes of the gastric and duodenal mucosa (21.9%), ruptured esophageal varices (9.4%), and esophageal reflux disease (8.0%). In 13.6% of patients the cause of hemorrhage did not lie in the upper digestive tract. In 50.3% of cases the gastrointestinal hemorrhage manifested itself by the discharge of melenic feces, and in 33.1% by hematemesis. 47.2% of our patients were aged over 60. CONCLUSIONS: Also in our society sequelae of ulcer disease are the most significant cause of gastrointestinal hemorrhage. Hemorrhages are frequent in elderly patients who usually have accompanying diseases.     

Interactions of polyclonal and monoclonal anti-glycoprotein 120 antibodies with oligomeric glycoprotein 120-glycoprotein 41 complexes of a primary HIV type 1 isolate: relationship to neutralization

The arterial ketone body ratio (AKBR) is considered to be an accurate index of the functional reserve of the liver, and the validity of this idea has been confirmed in the field of abdominal surgery. We found low AKBR value intracerebral hemorrhage patients and discussed the clinical significance of this finding in this paper. Twenty-five patients with intracerebral hemorrhage treated at our institution were included in this study. Their ages ranged from 42 to 86 years old (average 68.5 years). There were 13 cases of putaminal hemorrhage and 12 cases of thalamic hemorrhage. Evacuation of the hematoma or ventricle drainage was performed in 20 of these cases within 3 days after symptoms of intracerebral hemorrhage appeared. There were 12 cases with intraventricular hemorrhage. The outcome of these patients was as follows; 17 cases survived, eight cases died. We collected blood samples on days 1, 2, 3, 7 and 10 after the onset of symptoms (day 0) and measured the following: 1, beta-hydroxybutyrate; 2, acetoacetate; 3, epinephrine; 4, norepinephrine. On day 0 total ketone body levels were higher (246.3 +/- 231.7 mumol/l), AKBR values (0.60 +/- 0.18) were significantly lower than in the control group (2.05 +/- 1.35) (p < 0.001). However, both epinephrine and norepinephrine levels were significantly higher, 638.4 +/- 229.0 pg/ml and 1036.5 +/- 288.2 pg/ml, respectively. The AKBR value was 0.76 +/- 0.19 on day 1, 1.04 +/- 0.30 on day 2, and increased thereafter. In addition, the relation between sequential changes of AKBR in patients with intraventricular hemorrhage and outcome were also discussed. AKBR values are known to decrease not only in cases of hepatic failure, but in cases in which the liver energy charge is reduced, such as shock and hypoxemia, but no investigations have ever been performed to determine whether AKBR is altered in cerebrovascular disease. In this study, we found that AKBR values were lower in intracerebral hemorrhage, presumably due to reduced hepatic blood flow causes by increased levels of epinephrine and norepinephrine. In addition, our findings suggest that the fluctuations in AKBR values correlated with the outcome of intracerebral hemorrhage patients.     

Mechanical thrombolysis with the Amplatz thrombectomy catheter

The authors describe a rare case of rhinocerebral mucormycosis. This is an acute, suppurative mycosis with poor prognosis. It has a particular affinity for rhinocerebral tissue and less frequently affects pulmonary tissue. Mucormycosis affects immunosuppressed patients and more than 75% of the cases involve patients suffering from acidosis, especially diabetic ketoacidosis. One characteristic feature is that the blood vessels are flooded causing thromboses, infarction and emboli. The disease is spread through the blood vessels or by expansion. The first clinical symptoms can be confused with an early stage of acute sinusitis with mucosanguineous rhinorrhea, facial tumescence and pain. In 50% of the cases there is rhinocerebral and orbital involvement. If the disease remains untreated it can prove fatal in 10 to 14 days. Effective treatment relies on an early diagnosis and prompt administration of intravenous amphotericin B as well as avulsion of the necrotic areas. To date only 200 cases of this severe pathology have been described. The present work is an attempt to throw further light on this disorder.     

The efficacy of diaspirin crosslinked hemoglobin solution resuscitation in a model of uncontrolled hemorrhage

Controversy exists whether early aggressive fluid therapy in the setting of uncontrolled hemorrhage worsens outcome by increasing blood loss from injured vessels. Since diaspirin crosslinked hemoglobin (DCLHb) is a vasoactive, oxygen-carrying solution, we compared the effects of DCLHb with other resuscitative fluids on blood loss, hemodynamics, and tissue oxygen delivery in a model of uncontrolled hemorrhage. Anesthetized rats (250-350 g) were subjected to a 50% tail transection and resuscitated 15 minutes later with 1:1 DCLHb, 3:1 lactated Ringer's solution (LR), 1:1 hypertonic saline (7.5% HTS), or 1:1 human serum albumin (8.3% HSA) based on initial volume of blood loss (average 4.7 +/- 0.3 mL/kg). An unresuscitated group served as a control. Cumulative blood loss was measured at 5 hours postresuscitation. By 15 minutes after tail transection, mean arterial pressure (MAP) decreased 19.2 +/- 3.8 mm Hg from the baseline value (102 +/- 5 mm Hg). The DCLHb solution restored and maintained MAP and subcutaneous tissue oxygen tension at baseline values better than all other resuscitative fluids. Although blood loss in DCLHb-treated animals was greater than in unresuscitated animals, it was no different from other resuscitative fluids and less than with HSA. There was no difference in 24-hour survival between all treatment groups. In conclusion, DCLHb elevates MAP but does not exacerbate blood loss or compromise tissue oxygen delivery compared with other resuscitative fluids in this model of uncontrolled hemorrhage.     

Autoradiographic determination of local cerebral blood flow and local cerebral glucose utilization during chemical stimulation of the nucleus tractus solitarii of anesthetized rats

This study was conducted to determine whether the decrease in cerebral blood flow (CBF) observed during chemical stimulation of the nucleus tractus solitarius (NTS) can be explained by a decrease in cerebral metabolism. In anesthetized (urethane and chloralose), paralyzed and artificially ventilated rats, neurons in the NTS were chemically stimulated by microinjection of L-glutamate. Local cerebral blood flow (LCBF) and local cerebral glucose utilization (LCGU) were quantified in 43 brain structures by quantitative autoradiographic techniques using [14C]iodoantipyrine and 2-[14C]deoxyglucose, respectively. During chemical stimulation of the NTS (n = 6), LCBF decreased significantly in 32 of the 43 structures investigated when compared to either a control group with artificial cerebrospinal fluid injection (n = 6), or a controlled hemorrhage group (n = 5). In the controlled hemorrhage group, blood pressure was decreased to a degree comparable to that induced by microinjection of L-glutamate into the NTS. Mean blood flow of all structures investigated was significantly (P < 0.01) lower in the stimulation group than that in the control group and in the hemorrhage group. No significant differences in LCGU were observed between the three investigated groups in all structures examined except for an increase in LCGU in the chemically stimulated NTS site. It is concluded that the decrease in LCBF measured in most brain structures during chemical stimulation of the NTS is not caused by a decrease in LCGU in these structures and may therefore be explained by neurogenic influences on brain vessels.     

MR imaging in pretruncal nonaneurysmal subarachnoid hemorrhage: is it worthwhile?

BACKGROUND and PURPOSE: The cause of pretruncal (perimesencephalic) nonaneurysmal subarachnoid hemorrhage is not known. MRI of the brain or spine is often performed to exclude any other vascular abnormalities. Its diagnostic value is not known. METHODS: We used MR imaging of the brain with routine sequences, gadolinium enhancement, and additional thin T1-weighted axial sections following a triple dose of contrast. RESULTS: We performed MR imaging of the brain in 18 patients with a pretruncal nonaneurysmal subarachnoid hemorrhage. The focal nature of the subarachnoid hemorrhage exclusively in front of the brain stem was confirmed in 14 patients studied within 7 days of the ictus. No vascular abnormalities were found in 17 cases, including 14 patients with gadolinium enhancement. An incidental capillary telangiectasia was found in 1 patient. Fluid-attenuated inverse recovery MR additionally documented blood in the sulci due to cerebrospinal fluid recirculation of blood. Five patients underwent MR imaging of the spine, and no arteriovenous malformations were found. CONCLUSIONS: MR imaging did not reveal a source of pretruncal subarachnoid hemorrhage. The cost of MR imaging probably outweighs the benefit in the evaluation of this variant of subarachnoid hemorrhage.     

Anxiogenic-like effects of spontaneous and naloxone-precipitated opiate withdrawal in the elevated plus-maze

PURPOSE: Endopyelotomy has become the initial treatment of choice for ureteropelvic junction obstruction. Debate persists regarding the preferred approach (percutaneous or ureteroscopic) and the need for preoperative stenting. We review our experience with ureteroscopic endopyelotomy without preoperative stenting. MATERIALS AND METHODS: We treated 21 patients a mean of 37 years old who had ureteropelvic junction obstruction with ureteroscopy and without preoperative stenting. Endoluminal ultrasound was performed in all cases for imaging the periureteral anatomy. A minimum of 1 year of followup is available in all cases. Success was defined as pain-free status with resolution of obstruction on diuretic renal scintigraphy. RESULTS: Success was achieved in 17 of 21 patients (81%). Complications included stent irritation, postoperative urinary tract infection and stent displacement requiring repositioning in 1 case each. Crossing vessels in 57% of the patients affected success (67 versus 100% in those with and without crossing vessels, respectively). No patient had significant hemorrhage. CONCLUSIONS: Ureteroscopic endopyelotomy without preoperative stenting is effective and safe for ureteropelvic junction obstruction.     

Doppler ultrasound of the testis in azoospermic subjects as a parameter of testicular function

Azoospermia frequently represents the end-point of different pathological conditions that cause important quantitative and qualitative alterations of both spermatogenesis and testicular structure, including intratesticular blood vessels. In this study we performed colour Doppler ultrasound of the testis in 12 azoospermic subjects affected by primary testicular pathology (four bilateral post-orchitis, four postradiotheraphy for cancer, four post-traumatic) aged 28.2+/-3.3 (mean+/-SD) years, in six subjects affected by obstructive azoospermia aged 29.7+/-2.4 years and in 20 age-matched fertile subjects (aged 28.6+/-2.5 years). The analysis of intratesticular vessels per organ was quantified using a semiquantitative score: category 0, no vessels visible; category 1, between one and three intratesticular vessels visible; and category 2, more than three vessels visible. In obstructive azoospermic patients and in fertile subjects there were always more than three intratesticular vessels. No intratesticular vessels were detected in eight testes (33.3%) and fewer than three vessels in 16 testes (66.6%) in subjects affected by primary testicular pathology. In azoospermic subjects the testicular structure of the testis was evaluated by diagnostic fine needle aspiration cytology (FNAC) performed in the middle portion of the testis. In non-obstructive azoospermic patients this procedure showed the presence of only Sertoli cells in all cases. When detectable vessels were present, a new aspiration was performed in these areas. In 12 out of 16 cases, spermatogenetic cells including mature spermatozoa, were found when the FNAC was performed in testicular regions showing the presence of blood vessels. These results indicate that colour Doppler sonography of the testis may be useful in the differential diagnosis of azoospermia and suggest the evaluation of the intratesticular blood vessel distribution before performing any method to retrieve intratesticular spermatozoa for intracytoplasmic sperm injection.     

Antiphospholipid syndrome associated with progressive systemic sclerosis

Hemifacial spasm is a neurological disorder due to abnormal hyperactivity of the facial nerve. The most common cause of hemifacial spasm is a neuro-vascular conflict in the cerebellopontine angle between a vascular loop and the root of the facial nerve (96% of cases). Tumors are the cause of hemifacial spasm in only 1% of cases). The authors present their results in 100 patients who underwent microvascular decompression for essential hemifacial spasm between 1990 and 1995. They used microsurgical and endoscopic procedures by a minimal retrosigmoid approach in all cases. The most common offending vessels were the posterior inferior cerebellar artery (70%), the vertebral artery (41%) and the anterior inferior cerebellar artery (28%). An aberrant vein was found in 2 cases. There were 38% of multiple artery-nerve conflicts. Physiopathology of hemifacial spasm is explained by two principal theories: in the ephaptic theory, hyperactivity and an abnormal nervous impulse pathway are due to a short demyelinated area on the nerve trunk caused by the offending vessel, inducing short circuiting between adjacent nerve fibers. In the nuclear theory, hyperactivity of the facial nerve is due to an abnormal and automatic activity of the facial nerve nucleus itself, induced by the vessel. The authors used pre and postoperative electromyographic tests and intraoperative electromyographic tests. Their results tend to prove the nuclear theory. Ninety per cent of the patients had a good result, with a mean follow-up time of 30 months in 60 cases. In 82% of the cases, there was a total recovery after a single procedure. There was no mortality and no facial palsy. Hearing loss occurred in less than 5%.