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The mechanism of action of the A2A adenosine receptor agonist 2-p-(2-carboxyethyl) phenethylamino-5'-N-ethylcarboxamidoadenosine hydrochloride (CGS-21680) in the facilitation of spontaneous (isotonic and hypertonic condition) and K+-evoked acetylcholine (ACh) release was investigated in the mouse diaphragm muscles. At isotonic condition, the CGS-21680-induced excitatory effect on miniature end-plate potential (MEPP) frequency was not modified in the presence of CdCl2 and in a medium free of Ca2+ (0Ca2+-EGTA), but it was abolished after buffering the rise of intracellular Ca2+ with 1,2-bis-(2-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid tetra(acetoxy-methyl) (BAPTA-AM) and when the Ca2+-ATPase inhibitor thapsigargin was used to deplete intracellular Ca2+ stores. CGS-21680 did not have a direct effect on the Ca2+-independent neurotransmitter-releasing machinery, since the modulatory effect on the hypertonic response was also occluded by BAPTA-AM and thapsigargin. CGS-21680 facilitation on K+-evoked ACh release was not altered by the P/Q-type voltage-dependent calcium channel (VDCC) blocker ω-Agatoxin IVA, but it was completely prevented by both, the L-type VDCC blocker nitrendipine (which is known to immobilize their gating charges), or thapsigargin, suggesting that the effects of CGS-21680 on L-type VDCC and thapsigargin-sensitive internal stores are associated. We found that the VDCC pore blocker Cd2+ (2 mM Ca2+ or 0Ca2+-EGTA) failed to affect the CGS-21680 effect in high K+ whereas nitrendipine in 0Ca2+-EGTA+Cd2+ occluded its action. The blockade of Ca2+ release from endoplasmic reticulum with ryanodine antagonized the facilitating effect of CGS-21680 in control and high K+ concentration. It is concluded that, at the mouse neuromuscular junction, activation of A2A receptors facilitates spontaneous and K+-evoked ACh release by an external Ca2+-independent mechanism but that involves mobilization of Ca2+ from internal stores: during spontaneous ACh release stimulating directly the ryanodine-sensitive stores and, at high K+, probably modulating the L-type VDCCs which may cause the opening of the ryanodine receptors that would be directly coupled to the channels. In both cases, Ca2+ released from the endoplasmic reticulum would be capable of activating the exocytotic machinery, thus producing facilitation of ACh release.

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At the mouse neuromuscular junction, activation of adenosine A(1) and P2Y receptors inhibits acetylcholine release by an effect on voltage dependent calcium channels related to spontaneous and evoked secretion. However, an effect of purines upon the neurotransmitter-releasing machinery downstream of Ca(2+) influx cannot be ruled out. An excellent tool to study neurotransmitter exocytosis in a Ca(2+)-independent step is the hypertonic response. Intracellular recordings were performed on diaphragm fibers of CF1 mice to determine the action of the specific adenosine A(1) receptor agonist 2-chloro-N(6)-cyclopentyl-adenosine (CCPA) and the P2Y(12-13) agonist 2-methylthio-adenosine 5'-diphosphate (2-MeSADP) on the hypertonic response. Both purines significantly decreased such response (peak and area under the curve), and their effect was prevented by specific antagonists of A(1) and P2Y(12-13) receptors, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) and N-[2-(methylthioethyl)]-2-[3,3,3-trifluoropropyl]thio-5'-adenylic acid, monoanhydride with dichloromethylenebiphosphonic acid, tetrasodium salt (AR-C69931MX), respectively. Moreover, incubation of preparations only with the antagonists induced a higher response compared with controls, suggesting that endogenous ATP/ADP and adenosine are able to modulate the hypertonic response by activating their specific receptors. To search for the intracellular pathways involved in this effect, we studied the action of CCPA and 2-MeSADP in hypertonicity in the presence of inhibitors of several pathways. We found that the effect of CPPA was prevented by the calmodulin antagonist N-(6-aminohexil)-5-chloro-1-naphthalenesulfonamide hydrochloride (W-7) while that of 2-MeSADP was occluded by the protein kinase C antagonist chelerythrine and W-7. On the other hand, the inhibitors of protein kinase A (N-(2[pbromocinnamylamino]-ethyl)-5-isoquinolinesulfonamide, H-89) and phosphoinositide-3 kinase (PI3K) (2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one hydrochloride, LY-294002) did not modify the modulatory action in hypertonicity of both purines. Our results provide evidence that activation of A(1) and P2Y(12-13) receptors by CCPA and 2-MeSADP inhibits ACh release from mammalian motor nerve terminals through an effect on a Ca(2+)-independent step in the cascade of the exocytotic process. Since presynaptic calcium channels are intimately associated with components of the synaptic vesicle docking and fusion processes, further experiments could clarify if the actions of purines on calcium channels and on secretory machinery are related.

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At the neuromuscular junction, ATP is co-released with the neurotransmitter acetylcholine (ACh) and once in the synaptic space, it is degraded to the presynaptically active metabolite adenosine. Intracellular recordings were performed on diaphragm fibers of CF1 mice to determine the action of extracellular ATP (100 muM) and the slowly hydrolysable ATP analog 5'-adenylylimidodiphosphate lithium (betagamma-imido ATP) (30 muM) on miniature end-plate potential (MEPP) frequency. We found that application of ATP and betagamma-imido ATP decreased spontaneous secretion by 45.3% and 55.9% respectively. 8-Cyclopentyl-1,3-dipropylxanthine (DPCPX), a selective A(1) adenosine receptor antagonist and alpha,beta-methylene ADP sodium salt (alphabeta-MeADP), which is an inhibitor of ecto-5'-nucleotidase, did not prevent the inhibitory effect of ATP, demonstrating that the nucleotide is able to modulate spontaneous ACh release through a mechanism independent of the action of adenosine. Blockade of Ca(2+) channels by both, Cd(2+) or the combined application of nitrendipine and omega-conotoxin GVIA (omega-CgTx) (L-type and N-type Ca(2+) channel antagonists, respectively) prevented the effect of betagamma-imido ATP, indicating that the nucleotide modulates Ca(2+) influx through the voltage-dependent Ca(2+) channels related to spontaneous secretion. betagamma-Imido ATP-induced modulation was antagonized by the non-specific P2 receptor antagonist suramin and the P2Y receptor antagonist 1-amino-4-[[4-[[4-chloro-6-[[3(or4)-sulfophenyl] amino]-1,3,5-triazin-2-yl]amino]-3-sulfophenyl] amino]-9,10-dihydro-9,10-dioxo-2-anthracenesulfonic acid (reactive blue-2), but not by pyridoxal phosphate-6-azo(benzene-2,4-disulfonic acid) tetrasodium salt (PPADS), which has a preferential antagonist effect on P2X receptors. Pertussis toxin and N-ethylmaleimide (NEM), which are blockers of G(i/o) proteins, prevented the action of the nucleotide, suggesting that the effect is mediated by P2Y receptors coupled to G(i/o) proteins. The protein kinase C (PKC) antagonist chelerythrine and the calmodulin antagonist N-(6-aminohexil)-5-chloro-1-naphthalenesulfonamide hydrochloride (W-7) occluded the effect of betagamma-imido ATP, while the protein kinase A (PKA) antagonist KT-5720 and the inhibitor of the calcium/calmodulin-dependent protein kinase II (CAMKII) KN-62 failed to do so. betagamma-Imido ATP did not affect 10, 15 and 20 mM K(+)-evoked release and application of reactive blue-2 before incubation in high K(+) induced a higher asynchronous secretion. Thus, our results show that at mammalian neuromuscular junctions, ATP induces presynaptic inhibition of spontaneous ACh release due to the modulation of Ca(2+) channels related to tonic secretion through the activation of P2Y receptors coupled to G(i/o) proteins. We also demonstrated that at increasing degrees of membrane depolarization evoked by K(+), endogenously released ATP induces presynaptic inhibition as a means of preventing excessive neurotransmitter secretion.

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Pathology of chronic Chagas' disease involves peripheral nervous system (PNS) compromise. A high prevalence of antibodies reacting with nervous system antigens has been found in the sera of patients and infected animals, although their physiological role in mediating PNS tissue damage is unknown. Here, we demonstrate that epineural injection of sera from Trypanosoma cruzi infected mice affects the characteristics of the sciatic nerve action potential (SNAP) depending on the parasite strain. Sera from mice infected with the reticulotropic/neurotropic RA strain with reactivity against sciatic nerve (RA/Ne+ sera) induced delays on latency and diminished amplitudes 4 days after injection. Sera from mice infected with the myotropic CA-I strain failed to affect SNAP. Purified immunoglobulin (Ig)G from RA/Ne+ also diminished the amplitude of SNAP. Deposits of IgG labelling axonal fibres and/or myelin sheaths were detected in nerves injected with RA/Ne+ sera. No major histological damage or parasite DNA was found in those nerves. The SNAP changes after sera injection were similar to those observed in mice injected with trypomastigotes in the epineurum 17 days before and in chronically infected animals. This investigation suggests that autoantibodies triggered as a consequence of T. cruzi infection are able to mediate, at least in part, the electrophysiological abnormalities observed in PNS during the course of Chagas' disease.

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Regulation of neurotransmitter release is thought to involve modulation of the release probability by protein phosphorylation. Activation of the cAMP-protein kinase A (PKA) pathway has been shown to facilitate synaptic transmission in mammalian neuromuscular synapses, although the relevant phosphorylation targets are mostly unknown. We found that the inhibitor of the phosphodiesterase aminophylline (1 mM AMIN), the membrane-permeable analog of cAMP, 8-Br-cAMP (5 mM) and, the direct adenylate cyclase activator, forskolin (20 microM), induced an increase of miniature end-plate potentials (MEPPs) frequency in rat neuromuscular junctions. We investigated the possible involvement of the voltage-dependent calcium channels (VDCC), since these proteins are known to be phosphorylated by PKA. But this possibility was ruled out, since the increase in MEPPs frequency was not attenuated by the VDCC blocker Cd2+ (100 microM) and it was observed when AMIN was studied on hyperosmotic response, which is independent of [Ca2+]o and of Ca2+ influx through the VDCC. The lack of action of AMIN on MEPPs frequency when [Ca2+]i was diminished by exposing the preparations to zero Ca2+-EGTA solution (isotonic condition) or when nerve terminals were loaded with a permeant Ca2+ chelator (BAPTA-AM) (hypertonic condition), indicate that cAMP-mediated presynaptic facilitation is a function of nerve terminal Ca2+ concentration. We also found that AMIN exerted a comparable increase in MEPPs frequency in control and high K+ (10 and 15 mM), suggesting a single mechanism of action for spontaneous and K+-induced secretion.

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The case of a 72-year-old woman presenting sensory neuropathy and anti-Hu antibodies is reported. She was admitted in November 1995 with a one year history of sensory neuropathy. Her first symptoms were painful numbness and dysesthesias in both feet. She experienced progression of the sensory symptoms affecting upper limbs, and clumsiness of gait. One month before admission she complained of diminished strength in both hands. The neurologic examination showed anicocoric fixed pupils, with no reaction to light; convergence miosis was evident in the right eye (Argyll-Robertson pupil). In the lower limbs she had very mild distal weakness, and tendon reflexes were universally abolished. Pin and touch sensation, position sense and pallesthesia were absent in all four limbs. Romberg test was elicited, and a tabetic gait was patent. Pseudoathetotic movements were observed in hands and feet. An ulcer was present in the fifth finger of the right foot. Routine blood biochemistry and hematology showed a ESR of 105 and an increased IgG in the immune-electrophoretic run. Neurophysiologic evaluation disclosed a mild demyelinating neuropathy. Positive anti-Hu antibodies were found in the serum (Western blot - Athena Diagnostics); CSF was normal but not tested for anit-Hu. An abdominal CT scan disclosed multiple hypodense nodules in liver, right adrenal gland and peritoneum. A chest CT scan showed a hyperdense mass in the lower right pulmonary lobe and enlarged retrocava-pretracheal lymph nodes. A biopsy of the peritoneal nodule was performed, showing a metastatic small cell carcinoma. The patient died eight days after discharge. Although multiple organs were affected, she was independent until death, showing an indolent clinical course.

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Recent reports have shown that patients with Lambert-Eaton myasthenic syndrome (LEMS) improve transiently after high-dose intravenous immunoglobulin (IVIG) administration. Information about the usefulness of IVIG for long-term treatment is rather scanty. Our findings demonstrate the efficacy of monthly IVIG courses at a dose of 0.4 g/kg/day for 5 days, in a 41-year-old patient with LEMS without detectable malignancy. Improvement in limb strength, peak expiratory flow rate, and electrophysiological parameters, as well as clinical signs following IVIG, was evident as early as 7 days after the first course and is still maintained at 24-months follow-up.

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Spontaneous secretion of the neurotransmitter acetylcholine in mammalian neuromuscular synapsis depends on the Ca2+ content of nerve terminals. The Ca2+ electrochemical gradient favors the entry of this cation. We investigated the possible involvement of three voltage-dependent Ca2+ channels (VDCC) (L-, N-, and P/Q-types) on spontaneous transmitter, release at the rat neuromuscular junction. Miniature end-plate potential (MEPP) frequency was clearly reduced by 5 microM nifedipine, a blocker of the L-type VDCC, and to a lesser extent by the N-type VDCC blocker, omega-conotoxin GVIA (omega-CgTx, 5 microM). On the other hand, nifedipine and omega-CgTx had no effect on K(+)-induced transmitter secretion. omega-Agatoxin IVA (100 nM), a P/Q-type VDCC blocker, prevents acetylcholine release induced by K+ depolarization but failed to affect MEPP frequency in basal conditions. These results suggest that in the mammalian neuromuscular junction Ca2+ enters nerve terminals through at least three different channels, two of them (L- and N-types) mainly related to spontaneous acetylcholine release and the other (P/Q-type) mostly involved in depolarization-induced neurotransmitter release. Ca(2+)-binding molecule-related spontaneous release apparently binds Ca2+ very rapidly and would probably be located very close to Ca2+ channels, since the fast Ca2+ chelator (BAPTA-AM) significantly reduced MEPP frequency, whereas EGTA-AM, exhibiting slower kinetics, had a lower effect. The increase in MEPP frequency induced by exposing the preparation to hypertonic solutions was affected by neither external Ca2+ concentration nor L-, N-, and P/Q-type VDCC blockers, indicating that extracellular Ca2+ is not necessary to produce hyperosmotic neurosecretion. On the other hand, MEPP frequency was diminished by BAPTA-AM and EGTA-AM to the same extent, supporting the view that hypertonic response is promoted by "bulk" intracellular Ca2+ concentration increases.

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The balance between fibrinolytic activity and coagulation mechanisms seems to play an important role in the rebleeding of a subarachnoid hemorrhage (SAH) due to aneurysmatic rupture. In the present paper we describe our findings in a group of patients (n 10) with SAH. The plasmatic levels of fibrinogen and their degradation products (FDP), APTT, prothrombin activity and factor XIII were determined within 72 hours of initial bleeding or of eventual rebleeding. Factor XIII activity in the first bleeding was 82.1 +/- 4%, while the levels of FDP were 3.8 +/- 1 micrograms/ml. In patients presenting rebleeding (n 4), Factor XIII activity was 67.3 +/- 4.5% the day it manifested, which is significantly less than the values previously observed (p < 0.01), while the FDP level was 4.1 +/- 2 micrograms/ml. The decrease of factor XIII activity suggests an important role as regards clot stability in rupture location. It is also possible to attribute a rebleeding predictive value to its activity reduction.

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A case of a 35-year-old woman presenting infratentorial CNS lymphoma is reported. In 1990 she complained of diplopia, blurred vision and left horizontal nistagmus. An MRI disclosed a lesion in the medulla, pons, and cerebellar vermis and peduncles. Although no treatment was administered, a later RMI showed less extension of the tumor. One year after clinical diagnosis, she received corticosteroids; during the second year a stereotaxic biopsy of the cerebellar lesion was done showing a diffuse B cell non-Hodgkin's lymphoma. A whole brain irradiation was given (50 Gy). She did well for five years, and remains alive (79 months).

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Orthotopic placement of in vitro propagated Dunning R3327 AT-3 tumor cells resulted in a greater percentage of tumor takes and a two-fold shift in the exponential growth curve compared to flank implantation. The orthotopic tumor appeared to disseminate preferentially to regional lymph nodes, rather than to the lungs which is characteristic of flank tumors. The results suggest an important role of stromal-epithelial interactions in the growth of this tumor.

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Between 1974 and 1992, 118 patients with Myasthenia gravis (MG) were studied in our Hospital; 92 patients, followed up for longer than 6 months, were surveyed for therapeutical results. Patients were categorized according to Osserman criteria; 22 belonged to group I; 77 to group II; 4 to group III and 15 to group IV. MG predominated in females, the ratio was 1.87:1.0. This predominance was more obvious in patients below 35 years of age (2.68:1.0) than above (1.18:1.0). The greatest prevalence was found at the 3rd decade of life. The assessment of the diagnostic test is as follows: 1) edrophonium test was positive in 97% of 93 patients; 2) supramaximal repetitive stimulation performed in 3 different nerves yielded positive results in 83% of 118 patients. It is worth noting that the test was positive in 92% of patients with generalized MG while only 48% of those with ocular MG displayed positive results; 3) sera antiacetycholine receptor antibodies (ACRA) quantification produced positive results in 88% of the patients with generalized MG and in 33% of ocular MG. Altogether the positivity of this test was 83%; 4) passive transfer of patients sera (25 generalized and 2 ocular MG forms) to mice and measurement of mepp's amplitude in the phrenic-diaphragm in vitro preparation yielded positive results in 100% of the tested cases. Once the diagnosis was achieved, the characteristics of the thymus were studied combining pneumomediastinography and linear tomography (PT) in 60 patients. Thorax Computed tomography (CT) was performed in 51 patients. Of those patients who underwent thymectomy, the coherence between radiological and histological diagnosis for PT was 100% while for CT just 60%. More recently 14 patients were studied by combining both procedures. Reliability of this technique is currently under study. Therapeutical assessment was carried out adscribing patients to 5 different groups according to their response after treatment withdrawal; group 2: Improved, neither symptoms nor signs; group 1: Remission, neither symptoms nor signs while on medication or minimal disability without medication; group 3: Unchanged while on medication; group 4: Worse, patients with more severe or frequent signs and symptoms despite being on treatment, group 5: Death, patients who died due to respiratory failure. Groups 1 and 2 were considered successful while 3, 4 and 5 as unsuccessful. Treatment was based on the administration of anticholinesterase drugs (piridostigmine, neostigmine) in 113 patients. Of these, 35 received those drugs as the only medication of whom 39% obtained successful results. Steroids (methylprednisone) were administered to 75 patients, in 40 cases combined with anticholinesterase drugs.(ABSTRACT TRUNCATED AT 400 WORDS)

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Dolichoectasia of intracranial arteries is an infrequent disease with an incidence less than 0.05% in general population. It represents 7% of all intracranial aneurysms. Commonly seen in middle age patients with severe atherosclerosis and hypertension, the affected arteries include the basilar artery, supraclinoid segment of the internal carotid artery, middle, anterior and posterior cerebral arteries; males are more frequently affected. The clinical features of these fusiform aneurysms are divided in three categories: ische-mic, cranial nerve compression and signs from mass effect. Hemorrhage may also occur. Nine patients with symptomatic cerebral blood vessel dolichoectasias are presented. Six of them were males with moderate or severe hypertension. Lesions were confined to the basilar artery in 3 cases, carotid arteries and the middle cerebral artery in 1 case, and both systems were affected in 4 patients. Middle cerebral arteries were affected in 5 cases and the anterior cerebral artery in one. An isolated fusiform aneurysm of the posterior cerebral artery is also presented (case 8) (Table 3). Motor or sensory deficits, ataxia, dementia, hemifacial spasm and parkinsonism were observed. One patient died from cerebro-meningeal hemorrhage (Table 2). All patients were studied with computerized axial tomography of the brain, 5 cases with four vessel cerebral angiography, 4 cases with magnetic resonance imaging (MRI) and case 5 with MRI angiography. Clinical symptoms depend on the affected vascular territory, size of the aneurysm and compression of adjacent structures. The histopathologic findings are atheromatous lesions, disruption of the internal elastic membrane and fibrosis of the muscular wall. The resultant is a diffuse deficiency of the muscular wall and the internal elastic membrane. Recent advances in neuroimaging such as better resolution of CT scan, magnetic resonance images (MRI) and MRI angiography increased the diagnosis of this pathology showing clearly the affected vessels. This avoids the use of conventional or digital subtraction angiography, reserved only for diagnosing suspected saccular aneurysm, evidence of subarachnoid hemorrhage or planning surgical treatment. The treatment of this entity may be medical or surgical. There is evidence suggesting a more favorable outcome with anticoagulation therapy, although antiaggregation is a reasonable alternative. In our experience no difference in clinical outcome was evident. Surgical treatment of this type of aneurysm includes intra- or extracranial occlusion of parent artery, clipping or aneurysm trapping, tourniquet occlusion, and circumferential wrapping with clip reinforcement. Endovascular occlusion has been accomplished with detachable balloon technique or coils. No surgical attempt was done in our cases. The prognosis is variable depending on the patients age, vessels involved and clinical complications.(ABSTRACT TRUNCATED AT 400 WORDS)

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Inward rectifier potassium channels are thought to be related to resting membrane potential and in innervated skeletal muscle they are specially sensitive to the blocking action of Ba2+ ions. After denervation other channels are known to become resistant to their blockers. We study the effect of Ba2+ upon the inward rectifier potassium channels after denervation. Rat extensor digitorum longus fibers were equilibrated for 150 minutes in 150 mM KCl; when they were returned to 5 mM KCl the resting potential went back to its original level with a half time of 35 minutes. This repolarization was blocked by 5 mM BaCl2 in innervated muscles and in muscles denervated for 7 days, but failed to do so after 14 days of denervation. Voltage-clamp experiments performed in lumbricalis denervated muscle showed a lack of effect of Ba2+ upon potassium current after 18 days of denervation. This results suggest that the inward rectifier potassium channels become resistant to Ba2+ ions after denervation, indicating a neural influence.

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Between 1974 and 1992, 118 patients with Myasthenia gravis (MG) were studied in our Hospital; 92 patients, followed up for longer than 6 months, were surveyed for therapeutical results. Patients were categorized according to Osserman criteria; 22 belonged to group I; 77 to group II; 4 to group III and 15 to group IV. MG predominated in females, the ratio was 1.87:1.0. This predominance was more obvious in patients below 35 years of age (2.68:1.0) than above (1.18:1.0). The greatest prevalence was found at the 3rd decade of life. The assessment of the diagnostic test is as follows: 1) edrophonium test was positive in 97

of 93 patients; 2) supramaximal repetitive stimulation performed in 3 different nerves yielded positive results in 83

of 118 patients. It is worth noting that the test was positive in 92

of patients with generalized MG while only 48

of those with ocular MG displayed positive results; 3) sera antiacetycholine receptor antibodies (ACRA) quantification produced positive results in 88

of the patients with generalized MG and in 33

of ocular MG. Altogether the positivity of this test was 83

; 4) passive transfer of patients sera (25 generalized and 2 ocular MG forms) to mice and measurement of mepps amplitude in the phrenic-diaphragm in vitro preparation yielded positive results in 100

of the tested cases. Once the diagnosis was achieved, the characteristics of the thymus were studied combining pneumomediastinography and linear tomography (PT) in 60 patients. Thorax Computed tomography (CT) was performed in 51 patients. Of those patients who underwent thymectomy, the coherence between radiological and histological diagnosis for PT was 100

while for CT just 60

. More recently 14 patients were studied by combining both procedures. Reliability of this technique is currently under study. Therapeutical assessment was carried out adscribing patients to 5 different groups according to their response after treatment withdrawal; group 2: Improved, neither symptoms nor signs; group 1: Remission, neither symptoms nor signs while on medication or minimal disability without medication; group 3: Unchanged while on medication; group 4: Worse, patients with more severe or frequent signs and symptoms despite being on treatment, group 5: Death, patients who died due to respiratory failure. Groups 1 and 2 were considered successful while 3, 4 and 5 as unsuccessful. Treatment was based on the administration of anticholinesterase drugs (piridostigmine, neostigmine) in 113 patients. Of these, 35 received those drugs as the only medication of whom 39

obtained successful results. Steroids (methylprednisone) were administered to 75 patients, in 40 cases combined with anticholinesterase drugs.(ABSTRACT TRUNCATED AT 400 WORDS)

RESUMEN

Dolichoectasia of intracranial arteries is an infrequent disease with an incidence less than 0.05

in general population. It represents 7

of all intracranial aneurysms. Commonly seen in middle age patients with severe atherosclerosis and hypertension, the affected arteries include the basilar artery, supraclinoid segment of the internal carotid artery, middle, anterior and posterior cerebral arteries; males are more frequently affected. The clinical features of these fusiform aneurysms are divided in three categories: ische-mic, cranial nerve compression and signs from mass effect. Hemorrhage may also occur. Nine patients with symptomatic cerebral blood vessel dolichoectasias are presented. Six of them were males with moderate or severe hypertension. Lesions were confined to the basilar artery in 3 cases, carotid arteries and the middle cerebral artery in 1 case, and both systems were affected in 4 patients. Middle cerebral arteries were affected in 5 cases and the anterior cerebral artery in one. An isolated fusiform aneurysm of the posterior cerebral artery is also presented (case 8) (Table 3). Motor or sensory deficits, ataxia, dementia, hemifacial spasm and parkinsonism were observed. One patient died from cerebro-meningeal hemorrhage (Table 2). All patients were studied with computerized axial tomography of the brain, 5 cases with four vessel cerebral angiography, 4 cases with magnetic resonance imaging (MRI) and case 5 with MRI angiography. Clinical symptoms depend on the affected vascular territory, size of the aneurysm and compression of adjacent structures. The histopathologic findings are atheromatous lesions, disruption of the internal elastic membrane and fibrosis of the muscular wall. The resultant is a diffuse deficiency of the muscular wall and the internal elastic membrane. Recent advances in neuroimaging such as better resolution of CT scan, magnetic resonance images (MRI) and MRI angiography increased the diagnosis of this pathology showing clearly the affected vessels. This avoids the use of conventional or digital subtraction angiography, reserved only for diagnosing suspected saccular aneurysm, evidence of subarachnoid hemorrhage or planning surgical treatment. The treatment of this entity may be medical or surgical. There is evidence suggesting a more favorable outcome with anticoagulation therapy, although antiaggregation is a reasonable alternative. In our experience no difference in clinical outcome was evident. Surgical treatment of this type of aneurysm includes intra- or extracranial occlusion of parent artery, clipping or aneurysm trapping, tourniquet occlusion, and circumferential wrapping with clip reinforcement. Endovascular occlusion has been accomplished with detachable balloon technique or coils. No surgical attempt was done in our cases. The prognosis is variable depending on the patients age, vessels involved and clinical complications.(ABSTRACT TRUNCATED AT 400 WORDS)

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