Peripheral nerve mucoid degeneration involving the sciatic nerve.

Peripheral nerve mucoid degeneration (PNMD) is a rare non-neoplastic degenerative condition characterized by endoneural deposit of mucoid matrix. Herein, we report a case of PNMD involving the sciatic nerve with preoperative features, surgical treatment and pathological findings.

AMPA receptor activation regulates the glutamate metabotropic receptor stimulated phosphatidylinositol turnover in human cerebral cortex slices.

The effect of excitatory amino acids (EAA) on phosphatidylinositol (PI) turnover in human cerebral cortical slices was investigated. Trans-1-aminocyclopentane-1,3-dicarboxylic acid (ACPD) increased inositol phosphate (IP) formation in the 1-1000 microM range. Quisqualic acid (QA) was maximally effective at 10-100 microM, showing an inverse correlation between concentration and effect in the 100-1000 microM range. The glutamate metabotropic receptor antagonist 2-amino-3-phosphonopropionic acid (AP3), the ionotropic non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and the NMDA channel blocker dizolcipine (MK-801) failed to prevent the PI response to ACPD (1000 microM). However, CNQX (100 microM) modified the concentration-response curve of QA reducing the effect of QA 10 microM by approx. 50% and enhancing that of QA 1000 microM by 2-fold. In addition, CNQX (100 microM) together with MK-801 (100 microM) unmasked the ability of L-glutamate (L-GLU) 3000 microM to stimulate PI turnover. The effect of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) on the EAA-induced PI turnover was also studied. AMPA (0.1-1 microM) potentiated the response to submaximal (30 microM) ACPD and (1 microM) QA concentrations. However, higher AMPA concentrations (10 microM) failed to synergize with ACPD 30 microM and, in addition, inhibited the PI turnover maximally stimulated by QA 10 microM. These results further support the presence of the glutamate metabotropic receptor in the human neocortex. In addition, they show the occurrence of a concentration-related dual interaction between AMPA and glutamate metabotropic receptor activation in the IP formation in this brain area.

Inhibitory effect of NMDA receptor activation on quisqualate-stimulated phosphatidylinositol turnover in the human cerebral cortex.

The effect of excitatory amino acids (EAA) on the phosphatidylinositol (PI) turnover in human cerebral cortical slices was investigated. Quisqualic acid (QA) and, to lesser extent, ibotenic acid (IBO) at 10(-5)-10(-3) M increased inositol phosphate (IP) accumulation. L-Glutamic acid (L-glu), kainic acid (KA), alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid and N-methyl-D-aspartic acid (NMDA) were ineffective. NMDA dose-dependently antagonized the QA facilitatory effect. Such inhibition was prevented by the NMDA receptor complex antagonists (+)-5-methyl-10,11-dihydro-5H-dibenzo[a, d]cyclohepten-5,10-imine (MK-801) and by 3[+/-)-2-carboxypiperazin-4-yl)propyl-1-phosphonic acid. The effect of IBO (but not that of QA) was greatly potentiated by MK-801. These data suggest that the EAA metabotropic receptor described in the rodent brain is also present in human cerebral cortex and is negatively modulated by the NMDA receptor.

Noradrenergic modulation of gamma-aminobutyric acid outflow from the human cerebral cortex.

The noradrenergic modulation of endogenous gamma-aminobutyric acid (GABA) outflow from slices and synaptosomes prepared from human cerebral cortex biopsies has been studied. GABA outflow was responsive to depolarizing stimuli such as ouabain and high potassium. Basal GABA outflow in slices, but not in synaptosomes, appeared to be largely dependent upon neuronal activity, being prevented by tetrodotoxin (TTX). 10 mM K(+)-evoked outflow in synaptosomes also proved to be TTX sensitive. Norepinephrine (NE) concentration dependently increased basal GABA outflow both in slices and synaptosomes. This effect was alpha 1-adrenoreceptor-mediated because it was prevented by a selective antagonist of the alpha 1-adrenoreceptor class (prazosin) but not by the alpha 2 antagonist idazoxan. However, an alpha 2-mediated inhibitory modulation was also present in the preparations used, since (1) in slices, NE significantly inhibited GABA outflow in the presence of prazosin; (2) in synaptosomes, NE significantly inhibited 10 mM K(+)-evoked outflow in the presence of prazosin. Both of these effects were prevented by idazoxan. No beta-adrenoreceptor modulation could be demonstrated. A comparison between species was also conducted. The response to ouabain and to TTX proved similar in human, rat and guinea-pig cerebral cortex. In the most simple tissue preparation used (synaptosomes), a close similarity between the three species could be observed. In all species, NE stimulated basal GABA outflow, an effect prevented by prazosin. This suggests a predominant alpha 1-adrenoreceptor-mediated stimulatory effect. In a more complex preparation (slices), differences between species could be demonstrated.(ABSTRACT TRUNCATED AT 250 WORDS)

Occult cerebrovascular malformations after irradiation.

OBJECTIVE: It has recently been found that patients receiving cerebral irradiation can develop hemorrhagic dysangiogeneses simulating occult vascular malformations. To analyze this connection, we report on five patients with occult cerebrovascular malformations occurring after "standard" or focused irradiation performed for brain tumors in four patients and for a deep-seated cavernous angioma in one patient. METHODS: All lesions were within the radiation ports. The time interval between irradiation and the detection of the occult vascular malformations varied from 3 to 9 years; the ratio of female to male patients was 4:1. Four patients were < 15 years old when first irradiated. Four patients presented with acute symptoms (headache, vomiting, focal signs) and one was asymptomatic when the lesions were first detected. Serial magnetic resonance imaging scans were available in four patients and a computed tomographic scan in the other patient. RESULTS: The initial appearance was that of a hypointense T1-T2 focus; magnetic resonance imaging then revealed focal or multifocal T1 hyperintensity and T2 mixed signal intensity followed by a late ring of decreased signal intensity. Four patients were operated on and one was under neuroradiological monitoring. Histological features of these lesions included clusters of closely packed vascular spaces resembling cavernous malformations sometimes associated with a thrombosed thick-walled vein with intense hemosiderin deposition and fibroblastic proliferation; telangiectasic changes were also seen in the adjacent brain. CONCLUSION: Increased awareness of occult cerebrovascular malformations is necessary, because their occurrence is not infrequent and they have hemorrhagic potential. Children receiving cerebral irradiation are at greater risk of this complication.

Langerhans cell histiocytosis of the spine causing cord compression: case report.

A case of Langerhans cell histiocytosis of the spine causing myeloradiculopathy is reported. Almost complete regression of symptoms and signs was observed in the patient after surgical treatment and radiotherapy. The clinical and histological features of the disease are discussed. The literature dealing with the previously reported cases of spinal histiocytosis involving neural structures is reviewed.

Growth, subsequent bleeding, and de novo appearance of cerebral cavernous angiomas.

In a series of 145 patients with brain cavernous angiomas treated at our hospital in the last 16 years, the angiomas of 18 patients exhibited aggressive biological behavior characterized by recurrent overt bleeding, growth, or de novo appearance. The cavernomas were in the cerebellum in three patients, in the brain stem in one, in the thalamus in four, in the caudate nucleus in two, in the diencephalon in one, and in the white matter of the cerebral hemispheres in seven. Three of these patients suffered from the familial or multiple form of the disease, two were pregnant, three had previously been irradiated for other tumors, and one had been treated by radiosurgery in the past. Overall, new cavernous malformations not previously shown were discovered in six patients. In 10 patients (3 male and 7 female) presenting with recurrent hemorrhages, the mean period of time between bleedings was 11 months (range, 1 wk-3 yr). Eleven patients were treated by definitive surgery, and seven were conservatively treated. One patient with a diencephalic cavernoma died from progressive hypothalamic dysfunction; three patients in the nonsurgical group had repeated symptoms and were left with additional neurological deficits. The outcome of the surgical group was the same (seven patients) or improved (four patients). Risk factors favoring an aggressive behavior included pregnancy, familial or multiple form of the disease, previous whole brain or stereotactic radiotherapy, incomplete removal, brain location, and associated venous malformation. The female preponderance (female to male ratio, 13:5) may also suggest some role of hormonal factors in influencing the biological behavior of cavernous malformations.

A hazard of craniotomy in the sitting position: the posterior compartment syndrome of the thigh. Case report.

A bilateral posterior compartment syndrome of the thigh with a sciatic neuropathy in a patient following a craniotomy in the sitting position is described. The pathophysiology of the sciatic nerve dysfunction is discussed and the diagnostic value of computerized tomography is emphasized. Prompt decompression of the nerve is suggested.

Surgical treatment of spinal cavernous angiomas.

Cavernous angiomas are vascular malformations that can occur in several compartments of the spine. Depending on their location, these lesions present particular clinico-diagnostic findings, and may require different modalities of treatment. The authors report a series of 10 patients with vertebral, epidural, subdural extra- and intramedullary cavernous angiomas. Clinical and radiological features, as well as surgical results of this series are presented. The different modalities of surgical treatment of cavernous angiomas variously placed along the spine are discussed.

Surgical management of cerebral cavernous angiomas causing epilepsy.

Epilepsy is the most frequent presenting symptom in patients with cerebral cavernous angiomas. Surgical removal of these vascular malformations causing epilepsy is usually recommended for patients with disabling, intractable seizures, while conservative management is indicated for neurologically intact patients with well controlled seizures. In this paper is reported a retrospective series of 36 patients suffering epilepsy from cerebral cavernous angiomas, and admitted at our Institution between 1975 and 1992. All patients were surgically treated; mortality and morbility were absent. The mean follow-up period was 5.9 years, since the 36 patients were alive and available for a control review in December, 1993. Seizure outcome of the patients resulted in a complete cure of the epileptic disorders in 9 (25%), improved seizure control with decreased medication in other 11 (30.5%), and epilepsy control with the same preoperative therapy in the remaining 16 (44.5%) patients. Furthermore, patients with preoperative neurological signs associated to epilepsy resulted improved. The authors conclude that surgery, where it is unlikely to cause neurological deficits, may allow a definitive cure of epilepsy in patients with cerebral cavernous angiomas, preventing the possible risks from hemorrhage and mass effect.

Orbital cavernous angiomas: surgical experience on a series of 13 cases.

Cavernous angiomas of the orbit are benign vascular growths, commonly occurring in adults and usually causing a slowly progressive proptosis from their mass effect. These lesions have behavioural and radiological findings different from those of brain cavernous angiomas, probably due to their particular origin and structure. The authors present a surgical series of 13 patients with orbital cavernous angiomas. Complete excision of lesions, with histological diagnosis, was obtained in all the 13 cases. Results were good in 10 patients, while 2 remained clinically unchanged and another one showed acute visual deterioration after a period of postoperative clinical stabilization. The main clinical and radiological characteristics of orbital cavernous angiomas are analyzed, together with their surgical management.

Extradural hematomas of the posterior cranial fossa. Observations on a series of 32 consecutive cases treated after the introduction of computed tomography scanning.

A series of 32 patients with posterior fossa epidural hematoma treated after the introduction of computed tomography scanning between 1975 and March 1988 is presented. Sixteen patients harbored "pure" epidural hematomas, whereas 16 had other infratentorial or supratentorial traumatic lesions. Glasgow Coma Scale on admission was 7 or less in 10 patients, 8-12 in 11, and 13-14 in 11. Only six patients had a lucid interval. Thirty patients were treated surgically; two patients with small hematomas were treated conservatively. Overall mortality was 15.6%, with 0% for "pure" and 31.2% for "complicated" posterior fossa epidural hematomas. The value of routine computed tomography scanning is emphasized in cases with occipital skull fracture or when such fracture is found in patients undergoing emergency evacuation of supratentorial hematomas. The pertinent literature is addressed with special regard to the delayed occurrence, associated lesions, and mortality of posterior fossa epidural hematomas and to the role of computed tomography scanning.

Intraneural ganglion of the peroneal nerve: an unusual presentation. Case report.

The authors report an intraneural ganglion of the peroneal nerve at the fibular head, in which the external appearance of the nerve was normal at operation. Only the incision of the epineurium permitted discovery of the lesion.

Spinal cavernous angioma: a rare cause of subarachnoid hemorrhage.

A case of cervical intrathecal extramedullary cavernous angioma is presented. The rarity of this lesion in comparison with the more frequent vertebral cavernous angiomas with secondary extension to the epidural space is emphasized. The special features of this case are noted: the acute clinical onset due to recurrent subarachnoid hemorrhages, the visualization only by means of magnetic resonance imaging, and the unusual cervical level. The most debated characteristics of these lesions and the relevant literature are summarized.

Surgical management of cavernous angiomas in children.

Cavernous angiomas are vascular malformations affecting any part of the central nervous system (CNS). The management of asymptomatic cavernous angiomas is still debated due to their poorly understood natural history, although more data are now available regarding results of surgical treatment in symptomatic cases. The authors report their surgical experience with 18 pediatric patients operated on for symptomatic CNS cavernous angiomas. The children ranged in age from 10 months to 17 years, without a relevant sex difference. Cavernous angiomas were intracranial in 17 cases: 15 being in the supratentorial compartments and two in the cerebellum. Clinical manifestations were as follows: seizures in 11 cases, focal neurologic deficits in five, and headache in one. The 18th case was observed in a girl showing paraparesis in the spinal subdural-extramedullary space at T8-T9 level. Excision of four deep cerebral lesions was performed after stereotactic localization through non-eloquent cortex. Pathologic confirmation of cavernous angiomas was obtained in all patients. Mortality from surgical procedures was absent in this series. The follow-up period ranged from 1 to 16 years. All 11 epileptic patients obtained seizure control; improvement or stabilization of neurologic symptoms was observed in the remaining seven patients.

Interruption of the radial nerve at proximal level: reconstruction following anterior transposition.

The authors describe two cases of radial paralysis due to interruption in the proximal level, treated by autologous nerve grafting, following anterior transposition. At long-term follow-up, in one case after 12 years, there was good functional recovery, while in the second case there was still no recovery after 2 years. The surgical technique involving anterior transposition of the nerve is described, which in this type of lesion facilitates neurorrhaphy.

Isolated injury to a major branch of the posterior interosseous nerve of the forearm with surgical repair.

We report the case of a patient who sustained an isolated injury to one of the two main branches of the posterior interosseous nerve of the forearm. Repair by epineurial suture was followed by complete recovery.

Giant sacral schwannoma: removal by an anterior, transabdominal approach.

We report a case of a giant intrasacral schwannoma expanding into the presacral space. 'En bloc' resection was accomplished by an anterior, transabdominal approach. The advantages of such a procedure are discussed.

Intramedullary melanotic schwannoma. Report of a case and review of the literature.

A case of an intramedullary melanotic schwannoma located in the spinal cord at the T2-T3 level is described. The lesion occurred in a 44-year-old woman with a 10-year history of weakness and sensory numbness in both legs and feet. At operation the lesion appeared as a well-demarcated grey-brown intramedullary mass. Histologically, it was composed of interlacing bundles of spindle cells showing their cytoplasm filled with melanin. Among spinal cord neoplasms, melanotic schwannomas are rare tumours, which have apparently been reported only in three previous instances. The clinical, diagnostic and pathological features, as well as the possible aetiology of these rare tumours are discussed.

Results of surgery in children with cerebral cavernous angiomas causing epilepsy.

Epilepsy is the most frequent presenting symptom of cerebral cavernous angiomas or cavernomas, and surgical removal of these vascular malformations is considered the treatment of choice in patients with intractable or long-standing seizures, or in those with poor compliance to medical therapy. In this paper the results of surgical treatment in 11 children with seizures from cerebral cavernomas are reported. Surgery for deep-seated cavernomas was aided in 3 cases by a stereotactic localization technique, that allowed a limited approach with minimal brain damage. Major morbidity and mortality were absent; follow-up ranged between 1 to 16 years. Improved seizure control was seen in all the patients: eight (72%) became seizure-free with the same preoperative therapy; one became seizure-free with a lower drug dosage, and two (18%) were seizure-free without medical therapy. The removal of cavernomas prevented the risk of haemorrhages or further deficits from growth and, above all, avoided spreading and autonomization of the epileptogenic area induced by the cavernoma.