Security and reliability of CUSTOMBONE cranioplasties: A prospective multicentric study.

BACKGROUND: Repairing bone defects generated by craniectomy is a major therapeutic challenge in terms of bone consolidation as well as functional and cognitive recovery. Furthermore, these surgical procedures are often grafted with complications such as infections, breaches, displacements and rejections leading to failure and thus explantation of the prosthesis. OBJECTIVE: To evaluate cumulative explantation and infection rates following the implantation of a tailored cranioplasty CUSTOMBONE prosthesis made of porous hydroxyapatite. One hundred and ten consecutive patients requiring cranial reconstruction for a bone defect were prospectively included in a multicenter study constituted of 21 centres between December 2012 and July 2014. Follow-up lasted 2 years. RESULTS: Mean age of patients included in the study was 42±15 years old (y.o), composed mainly by men (57.27%). Explantations of the CUSTOMBONE prosthesis were performed in 13/110 (11.8%) patients, significantly due to infections: 9/13 (69.2%) (p<0.0001), with 2 (15.4%) implant fracture, 1 (7.7%) skin defect and 1 (7.7%) following the mobilization of the implant. Cumulative explantation rates were successively 4.6% (SD 2.0), 7.4% (SD 2.5), 9.4% (SD 2.8) and 11.8% (SD 2.9%) at 2, 6, 12 and 24 months. Infections were identified in 16/110 (14.5%): 8/16 (50%) superficial and 8/16 (50%) deep. None of the following elements, whether demographic characteristics, indications, size, location of the implant, redo surgery, co-morbidities or medical history, were statistically identified as risk factors for prosthesis explantation or infection. CONCLUSION: Our study provides relevant clinical evidence on the performance and safety of CUSTOMBONE prosthesis in cranial procedures. Complications that are difficulty incompressible mainly occur during the first 6 months, but can appear at a later stage (>1 year). Thus assiduous, regular and long-term surveillances are necessary.

The nuclear DICER-circular RNA complex drives the deregulation of the glioblastoma cell microRNAome.

The assortment of cellular microRNAs ("microRNAome") is a vital readout of cellular homeostasis, but the mechanisms that regulate the microRNAome are poorly understood. The microRNAome of glioblastoma is substantially down-regulated in comparison to the normal brain. Here, we find malfunction of the posttranscriptional maturation of the glioblastoma microRNAome and link it to aberrant nuclear localization of DICER, the major enzymatic complex responsible for microRNA maturation. Analysis of DICER's nuclear interactome reveals the presence of an RNA binding protein, RBM3, and of a circular RNA, circ2082, within the complex. Targeting of this complex by knockdown of circ2082 results in the restoration of cytosolic localization of DICER and widespread derepression of the microRNAome, leading to transcriptome-wide rearrangements that mitigate the tumorigenicity of glioblastoma cells in vitro and in vivo with correlation to favorable outcomes in patients with glioblastoma. These findings uncover the mechanistic foundation of microRNAome deregulation in malignant cells.

Is spinal cord stimulation safe? A review of 13 years of implantations and complications.

OBJECTIVE: The aim of this review was to evaluate the complications of spinal cord stimulation (SCS) for chronic pain. METHODS: This was a retrospective case series of 212 patients treated with SCS for chronic lower-limb neuropathic pain between March 2002 and February 2015 in a Reims academic hospital. All patients received a surgically implanted paddle-type electrode. Complications with this technique are here described and analyzed, and other treatment and preventative methods proposed. RESULTS: The major indication was 'failed back surgery syndrome', and 74 (35%) patients experienced complications, of which 57% were benign, while 42% required invasive treatment. Most frequent complications (n=22, 10%) were hardware malfunctions. There were two cases (0.9%) of postoperative neurological deficit and nine (4.2%) with postoperative infections. All patients received the appropriate treatment for their complication. CONCLUSION: Despite the presence of complications, SCS is still a safe technique, although careful patient selection and proper surgical technique can help to avoid major complications.

Multicolumn spinal cord stimulation for significant low back pain in failed back surgery syndrome: design of a national, multicentre, randomized, controlled health economics trial (ESTIMET Study).

BACKGROUND: Many studies have demonstrated the efficacy of spinal cord stimulation (SCS) for chronic neuropathic radicular pain over recent decades, but despite global favourable outcomes in failed back surgery syndrome (FBSS) with leg pain, the back pain component remains poorly controlled by neurostimulation. Technological and scientific progress has led to the development of new SCS leads, comprising a multicolumn design and a greater number of contacts. The efficacy of multicolumn SCS lead configurations for the treatment of the back pain component of FBSS has recently been suggested by pilot studies. However, a randomized controlled trial must be conducted to confirm the efficacy of new generation multicolumn SCS. Évaluation médico-économique de la STImulation MEdullaire mulTi-colonnes (ESTIMET) is a multicentre, randomized study designed to compare the clinical efficacy and health economics aspects of mono- vs. multicolumn SCS lead programming in FBSS patients with radicular pain and significant back pain. MATERIALS AND METHODS: FBSS patients with a radicular pain VAS score≥50mm, associated with a significant back pain component were recruited in 14 centres in France and implanted with multicolumn SCS. Before the lead implantation procedure, they were 1:1 randomized to monocolumn SCS (group 1) or multicolumn SCS (group 2). Programming was performed using only one column for group 1 and full use of the 3 columns for group 2. Outcome assessment was performed at baseline (pre-implantation), and 1, 3, 6 and 12months post-implantation. The primary outcome measure was a reduction of the severity of low back pain (bVAS reduction≥50%) at the 6-month visit. Additional outcome measures were changes in global pain, leg pain, paraesthesia coverage mapping, functional capacities, quality of life, neuropsychological aspects, patient satisfaction and healthcare resource consumption. TRIAL STATUS: Trial recruitment started in May 2012. As of September 2013, all 14 study centres have been initiated and 112/115 patients have been enrolled. Preliminary results are expected to be published in 2015. TRIAL REGISTRATION: Clinical trial registration information-URL: www.clinicaltrials.gov. Unique identifier NCT01628237.

[Management of WHO grade II and II meningiomas: retrospective study of surgical series of 36 cases at a single institution]. / Prise en charge des méningiomes OMS grade II et III : étude rétrospective monocentrique d'une série chirurgicale de 36 cas.

INTRODUCTION: Atypical and malignant meningiomas are a rare disease whose histological definition is still recent. Their management is not consensual. The aim of this study was to review the outcome, prognostic factors and the role of complementary therapies. PATIENTS AND METHODS: Between 1999 and 2007, 36 patients with atypical or malignant meningiomas were managed in our hospital. All surgical specimens were reviewed according to the 2007 WHO classification system. The sex ratio was 1.25 male, the median age was 59 years. The median follow-up was 55 months. Thirty meningiomas were atypical and six were malignant. RESULTS: Five and 10 years overall survival rate are respectively 72 and 41%, whereas 5 and 10 years progression free survival rate are 61 and 23%. We only identify female sex, age over 70 years and Karnofsky status under 70% as negative prognostic factors. CONCLUSION: Atypical and malignant meningiomas are difficult to manage and have high recurrence and poor survival rates. The prognostic of OMS II meningiomas is heterogeneous. Adjuvant radiation therapy is recommended in case of malignant menigioma or in case of atypical meningioma if incomplete surgical excision is performed.

[Feasibility of auditory cortical stimulation for the treatment of tinnitus. Three case reports]. / Protocole de prise en charge neurochirurgicale des acouphènes invalidants: à propos de trois cas.

UNLABELLED: Tinnitus is a public health issue in France. Around 1 % of the population is affected and 30,000 people are handicapped in their daily life. The treatments available for disabling tinnitus have until now been disappointing. We report our experience on the treatment of these patients in neurosurgery. PATIENT AND METHODS: Between 2006 and 2008, transcranial magnetic stimulation (rTMS) was performed following several supraliminal and subliminal protocols in 16 patients whose mean age was 47 years (range, 35-71). All patients underwent anatomical and functional MRI of the auditory cortex before and 18 h after rTMS, to straddle the primary and secondary auditory cortices. All patients underwent audiometric testing by an ENT physician. RESULTS: Nine patients responded with rTMS. After these investigations, two quadrapolar electrodes (Resume), connected to a stimulating device implanted under the skin (Synergy, from Medtronic), were extradurally implanted in three patients. The electrodes were placed between the primary and secondary auditory cortices. The mean follow-up was 25 months and significant improvement was found in these patients. CONCLUSION: The feasibility of cortical stimulation in symptomatic treatment of tinnitus was demonstrated by this preparatory work. The intermediate- and long-term therapeutic effects remain to be evaluated.

Hydraulic and biochemical analyses on full-scale sludge consolidation reed beds in Tuscany (Italy).

The management of sewage sludge has recently become one of the most significant challenges in wastewater management. Reed bed systems appear to be an efficient and economical solution for sludge management in small wastewater treatment plants. Four years ago, one of the holding companies for water and wastewater in central Italy adopted this technology in 6 wastewater treatment plants. Hydraulic and biochemical analyses were performed on the most representative site to asses the behaviour of reed beds with regard to dewatering, mineralization and humification of disposed sludge. Moreover, daily water content analysis were performed in the interval between subsequent sludge loadings. Results indicated a decrease of sludge volume by about 93% on a yearly basis. Biochemical analysis highlighted that mineralization processes decrease over time due to a rapid decrease of microbial activity and labile substrates, such as DHase enzyme and water-soluble carbon and ammonium, respectively. Moreover, a significant interrelationship between the parameters linked with mineralization was found: after two years of operation, the process of mineralization of organic matter is still predominant in the humification of organic matter. Daily water content data were used to define a semi empirical equation describing the dynamics of the dewatering process. Overall, the use of sludge reed beds resulted feasible, ecologically sustainable and cost-effective.

[Clostridial brain abscess after glioblastoma resection: case report and critical review of the literature]. / Abcès cérébral àClostridium perfringens après chirurgie d'exérèse d'un glioblastome: à propos d'un cas et revue de la littérature.

Clostridium perfringens is rare in neurosurgery. The source of clostridial brain abscess is usually a penetrating head injury. We report the case of a 57-year-old man who had parietal glioblastoma resection with local carmustine chemotherapy and who presented a clostridial brain abscess three weeks later. Progression was especially brutal, leading to patient's death in few hours. We discuss the etiology and progression of this case compared to the data reported in the literature.

[Nocardia brain abscess: features, therapeutic strategies and outcome]. / Abcès cérébraux àNocardia: caractéristiques radiocliniques et prise en charge thérapeutique.

BACKGROUND AND PURPOSE: Nocardia species is an aerobic soil-saprophyte bacterium, responsible for rare opportunistic infections, mainly reported in immunocompromised patients. Nocardia brain abscess accounts for 1 to 2% of cerebral abscesses. Prognosis is poor. METHODS: We describe clinical, radiological and bacteriological findings along with therapeutic aspects for five patients and review the literature on Nocardia cerebral abscess. RESULTS: The clinical features of Nocardia brain abscess are insidious and nonspecific, occurring frequently with a medical background of obvious or latent immunodeficiency; fever, if any, is observed subordinate to extracerebral nocardiosis. Computerized tomography scan and conventional magnetic resonance (MR) scan show lesions with a necrotic core and multilobed thick walls enhancing after injection of gadolinium or iodine. Abscesses are mainly located in the brain stem, basal ganglia and cerebral cortex of the frontal, parietal and occipital lobes; cerebellar and spinal locations are uncommon. MR diffusion-weighted imaging with calculation of apparent diffusion coefficient and proton MR spectroscopy can provide additional data for accurate differential diagnosis between abscess and other necrotic lesions, such as tumor and cyst formations. Bacteriological identification has progressed with advances in molecular microbiology: 16S rRNA sequencing, allowing a more rapid routine identification of Nocardia strains from clinical samples. Clinical management of patients with a Nocardia brain abscess relies upon early use of intravenous antibiotics adapted to the strains identified and their susceptibility. Most Nocardia strains display susceptibility to cotrimoxazol, amikacin and linezolid, but develop beta-lactamase activity. CONCLUSIONS: Early pus samples, obtained by biopsy or surgical resection, are needed to establish a certain bacteriological diagnosis and initiate appropriate intravenous antibiotics.

[Fractionated stereotactic radiotherapy for optic nerve sheath meningioma: eight cases]. / Radiothérapie stéréotaxique fractionnée des méningiomes de la gaine du nerf optique: à propos de huit cas.

UNLABELLED: Optic nerve sheath meningioma (ONSM) accounts for one-third of primary optic nerve tumors, and 2% of all meningiomas. ONSM must be distinguished from other meningiomas, in particular from cavernous meningiomas because of the different prognosis and treatment. The most frequent clinical sign is a progressive or sudden unilateral visual loss. Treatment of ONSM is still subject to discussion. This report covers a series of eight ONSM patients treated with fractionated stereotactic radiotherapy. MATERIAL AND METHODS: Between 2000 and 2006, we managed eight patients with ONSM. The average patient age was 47 years. There were five women and three men. The most frequent clinical signs were visual loss (100%), proptosis (35%), diplopia (25%). One patient was initially treated with surgery. All patient have been treated by fractionated stereotactic radiotherapy. 45 Gy in 25 fractions were delivered on the meningioma area at a rate of 5 fractions of 1.8 Gy per week. We used a Brainlab framework associated with a thermo-formed mask. A computed tomography then magnetic resonance imaging was obtained for each patient. The data was merged and planning took place on a Brainlab dosimetric console. The treatment was performed with a head-only Varion linear accelerator, with a Brainlab multi-blade collimator. RESULTS: The average follow-up was 27 months. Each patient had a complete radiological and ophthalmologic exam every 3 months during the first year, then every 6 months thereafter. Tumor control rate was 100%. Vision was re-established in five patients and three patients had improvement, including one patient during treatment. 100% of proptosis and diplopias regressed. No side effect was reported. CONCLUSION: This is still a preliminary study, but the results suggest that fractionated stereotactic radiotherapy may emerge as a primary treatment for ONSM, delaying surgery, which has proven functionally disappointing.

[Dilatation of Virchow-Robin perivascular spaces (types III cerebral lacunae): radio-clinical correlations]. / Dilatation des espaces périvasculaires de Virchow-Robin (Lacunes de type III): corrélations radio-cliniques.

BACKGROUND AND PURPOSE: Virchow-Robin spaces are pia-lined extensions of the subarachnoid space surrounding the path of brain vessels. When enlarged, such dilated perivascular spaces are often seen as foci of cerebrospinal fluid signal on MRI or CT scan. These foci are found in patients with miscellaneous clinical status. It is necessary to determine the radiological significance and clinical associations, if any, in such patients in order to give them the appropriate treatment. METHODS: We describe the clinical and radiological findings of five patients and review the literature on perivascular Virchow-Robin spaces. RESULTS: The mechanisms of dilated Virchow-Robin spaces are still not well understood. Such dilated perivascular spaces are found in two locations: typically in the high-convexity white matter of healthy elderly subjects, or surrounding the lenticulostriate vessels as they enter the basal ganglia. On MR images, they may be confused with lacunar infarcts. Most of the patients present with no symptoms: small dilatations located in the high convexity actually represent an anatomic variant, also called "état criblé". Sometimes, giant dilatations, or Poirier's type IIIb "expanding lacunae", found in the basal ganglia and midbrain may result in symptomatic hydrocephalus needing appropriate treatment. For other miscellaneous symptoms as headache, generalized epilepsy, dysmorphy, macrocephaly, there is no reliable correlation with enlarged perivascular spaces seen on MR images. CONCLUSIONS: The real symptomatic dilated perivascular spaces need appropriate and quick treatment. Most of the other patients present with no symptoms and will remain asymptomatic.

Genome-wide scan supports the existence of a susceptibility locus for schizophrenia and bipolar disorder on chromosome 15q26.

Schizophrenia (SZ) and bipolar disorder (BPD) are two severe psychiatric diseases with a strong genetic component. In agreement with the 'continuum theory', which suggests an overlap between these disorders, the existence of genes that affect simultaneously susceptibility to SZ and BPD has been hypothesized. In this study we performed a 7.5 cM genome scan in a sample of 16 families affected by SZ and BPD, all originating from the same northeast Italian population. Using both parametric and non-parametric analyses we identified linkage peaks on four regions (1p, 1q, 4p and 15q), which were then subjected to a follow-up study with an increased marker density. The strongest linkage was obtained on chromosome 15q26 with a non-parametric linkage of 3.05 for marker D15S1014 (nominal P=0.00197). Interestingly, evidence for linkage with the same marker has been reported previously by an independent study performed on SZ and BPD families from Quebec. In this region, the putative susceptibility gene ST8SIA2 (also known as SIAT8B) was recently associated with SZ in a Japanese sample. However, our allele frequency analyses of the two single-nucleotide polymorphisms (SNPs) with putative functional outcome (rs3759916 and rs3759914) suggest that these polymorphisms are unlikely to be directly involved in SZ in our population. In conclusion, our results support the presence of a gene in 15q26 that influences the susceptibility to both SZ and BPD.

Genetic strategies for brain tumor therapy.

Gene therapy is a potentially useful approach in the treatment of human brain tumors, which are notoriously refractory to conventional approaches. Most human clinical trials to date have been unsuccessful in terms of improving patient outcome. Recent improvements in viral vectors, the development of stem cell technology, and increased understanding of the mechanism of action of therapeutic transgenes provide hope that the next generation of gene therapeutics may show increased efficacy in treatment of this devastating disease.

[Unsuccessful surgery of Cushing's disease. Role and efficacy of fractionated stereotactic radiotherapy]. / Echec après chirurgie de la maladie de Cushing: rôle et résultats de la radiothérapie stéréotaxique fractionnée (RSF).

BACKGROUND AND PURPOSE: To optimize and reduce the toxicity of pituitary adenoma irradiation, we evaluated the feasibility and effectiveness of fractionated stereotactic radiotherapy (FSR) in 51 patients with functional adenoma; 12 of them had Cushing's disease. PATIENTS AND METHODS: Eleven females and one male, median age: 49 years, 8 of them relapsed and 4 had persistent hormonal secretion after surgery. The delivered dose was 50 grays (Gy) (5 x 1.8 Gy/week) using 5 convergent micro-beams scanning in arc therapy mode. The median planned target volume (PTV) receiving 90 to 100% of the total dose was 2,1 cm(3). We used relocatable non-invasive stereotactic device Brain Lab, and adapted Linac for stereotactic radiotherapy. RESULTS: Nine out of twelve patients (75%) presented with complete remission after a median time of 29 months, 3/12 patients with partial remission. Actuarial probability to have hormonal persistent secretion was 88% at on year, 44% from 3 to 5 years, 22% at 7 years, and 11% to 0% after 7 years. The 12-corticotroph adenomas were significantly (p=0.007) more radiosensitive than 39 non-corticotroph adenomas. Toxicity was significantly lower for corticotrope adenoma, with no radio-induced pituitary deficiency and no neurological or optic injury. CONCLUSIONS: Combined surgery and FSR appears to be safe and effective for treatment of pituitary adenomas. However, long-term follow-up is required to determine the impact in terms of tumor response and hormone deficiency. The focused treated volume obtained by FSR seems more suitable for these benign tumours than standard radiotherapy. In addition to this conformal approach, the use of standard fractionation reduced the risk of severe damage to the optic chiasma, which is sometimes observed after radiosurgery and is inherent in single fraction radiotherapy.

Differentiated cerebrovascular effects of physostigmine and tacrine in cortical areas deafferented from the nucleus basalis magnocellularis suggest involvement of basalocortical projections to microvessels.

Cholinesterase inhibitors used to treat Alzheimer's disease according to the principle of cholinergic replacement therapy have proved to be less beneficial than expected. The present study was designed to investigate the cerebrovascular response to physostigmine and tacrine in the experimental model of lesioning of the nucleus basalis magnocellularis (NBM), a model involving a cholinergic deficit. Regional cerebral blood flow was measured by the [14C]iodoantipyrine tissue sampling technique in conscious rats infused with i.v. physostigmine (0.2 mg/kg/h), tacrine (8 mg/kg/h), or saline, 3-5 weeks after unilateral lesion of the NBM with ibotenic acid. Physostigmine and tacrine dose-dependently increased blood flow in most cortical and subcortical regions compared to the control group. However, physostigmine caused smaller blood flow increases in several areas, mostly cortical, of the lesioned compared to the intact hemisphere. The converse was observed with tacrine. A facilitated circulatory response appeared in cortical areas deafferented from the NBM, especially in the frontal cortex. These results provide evidence for distinct NBM-dependent components of the cortical cerebrovascular effects of physostigmine and tacrine. They suggest the involvement of different cellular postsynaptic targets of the NBM. The physostigmine-type effects could involve direct projects onto an inhibitory cortical interneuron supersensitized by deafferentation. This arrangement may explain why physostigmine and perhaps other cholinergic agonists are unable to specifically compensate for a deficit in NBM functioning. The tacrine-type effects presumably involve projections to the microvasculature, including perivascular astrocytes. The neurovascular junction would be sensitized by deafferentation from the NBM. Our data suggest that the regulatory mechanisms of blood flow originating in the NBM might constitute a target of neurodegenerative processes of Alzheimer's disease.

[Fractionated stereotactic radiotherapy: results in hypophyseal adenomas, acoustic neurinomas, and meningiomas of the cavernous sinus]. / Radiothérapie stéréotaxique fractionnée: résultats dans les adénomes hypophysaires, les neurinomes de l'acoustique et les méningiomes du sinus caverneux.

PURPOSE: In order to optimize cerebral benign tumor irradiation, fractionated stereotactic radiotherapy allows a focused-volume irradiation (2.1 cm3, 16 mm diameter) under standard fractionation conditions. Results of a retrospective and multicentric analysis are presented. PATIENTS AND METHODS: Fractionated stereotactic radiotherapy uses the ballistic principles of the radiosurgery: stereotactic localization, multi-beam irradiation, secondary collimation, three-dimensional dosimetry. Standard fractionation is possible with a re-locatable non-invasive stereotactic device. The technique has been used for treating pituitary adenomas (86 patients), acoustic neuromas (32 patients) and cavernous meningiomas (26 patients). RESULTS: 1) pituitary adenomas: cumulative tumoral objective-response rates (42 patients) were respectively 42%, 69% and 88% at 24, 48 and 60 months. The cumulative endocrinologic objective-response rates (32 patients) were respectively 53%, 75% and 85% at 24, 48 and 60 months. The cumulative risk of radio-induced hormonal deficiency varied from 18% (growth hormone [GH]) to 42% for TSH (thyroid stimulating hormone) at 48 months. No other complication was observed; 2) acoustic neuromas: 33 tumors, < 25 mm in diameter, were treated in 32 patients. Tumor control was observed in 29/33 tumors: 14 were stable, 15 decreased and three progressed. Useful hearing was maintained in 9/10 patients. Only three patients (9%) presented persistent complications; 3) cavernous meningioma: 17/19 clinical responses were noted, 20 tumoral stabilisations, one partial response and one progression (22 magnetic resonance imaging [MRI] evaluable patients). One unilateral radio-induced blindness was observed. CONCLUSION: For these benign tumors, the focused target volume obtained by the fractionated stereotactic radiotherapy seems to be better adapted to the treatment of limited benign tumors than standard radiotherapy. The use of standard fractionation reduces the risk of severe normal tissue damage, sometimes observed for radiosurgery and inherent in the use of single fraction.

[Postoperative spinal extradural hematomas. 14 cases]. / Hématomes extra-duraux rachidiens post-opératoires. Quatorze observations.

We report 14 cases of post-operative spinal epidural hematoma and compare them with 17 cases reported in the literature. These 14 cases have been drawn from a continuous series of 7950 patients operated on at our institution by the posterior route for a non-traumatic spinal pathology. The symptom-free period after initial surgery was shorter than 5 hours in 13 cases out of 14. The clinical picture was characteristic 11 times. It started with a stabbing pain in the operated site, followed by paresthesia, radicular pain and neurologic palsy which were always bilateral even when the operation had been unilateral. The diagnosis was always established rapidly when the compression was cervical or thoracic and with some delay when the lumbar area was concerned. All patients, except one, have been reoperated without any radiological investigation. The source of bleeding was found 12 time out of 14. Full recovery was obtained in all 14 patients but delayed recovery of a few weeks occurred in 3 patients for whom reoperation was delayed. None of the potentiating factors studied in this work were found to be decisive. Post-operative spinal epidural hematoma is a rather uncommon complication of spinal surgery occurring at a rate of 1 to 2 per thousand. The diagnosis is more often obvious because its clinical picture is similar to that of spontaneous spinal epidural hematoma. Early reoperation allows a full recovery. Special attention during the first six post-operative hours for all patients after spinal surgery is essential for early detection of such a complication.

Tacrine overcompensates for the decreased blood flow induced by basal forebrain lesion in the rat.

The effects of tacrine on the cerebral blood flow (CBF) were investigated according to an experimental model of the cholinergic hypothesis in rats with unilateral lesion of the substantia innominata (SI). CBF was measured 1-2 weeks following SI lesion with ibotenic acid, using the tissue sampling [14C]iodoantipyrine technique in three groups of lesioned rats infused i.v. with tacrine at 3 or 8 mg kg-1 h-1 or with saline. SI lesioning resulted in moderate, significant blood flow decreases in the parietal, frontal and occipital cortical areas. In the intact hemi-brain, tacrine at a dose of 3 mg kg-1 h-1 had no significant effect, but at 8 mg kg-1 h-1 tacrine increased the blood flow in most of the cortical and subcortical regions investigated. The increases ranged from 21% (hypothalamus) to 101% (parietal cortex) compared with controls. Tacrine had greater effects in the lesioned hemisphere, even at the dose of 3 mg kg-1 h-1. The flow increases in the frontal or parietal cortex of the lesioned hemisphere were 1.5-3.6 times greater than in the intact hemisphere. Thus, in contrast to what was expected, tacrine overcompensates for the cerebrovascular effects of SI lesions.

Lhermitte-Duclos disease associated with syringomyelia.

A 23-year-old man presented with a 2-week history of intracranial hypertension. CT showed a large, nonenhancing cerebellar mass with surrounding calcification and displacement of the fourth ventricle. MRI revealed a septate lesion, with low signal on T1-weighted and high signal on T2-weighted images. The cerebellar tonsils were displaced below the foramen magnum and there was associated syringomyelia. The MRI features were characteristic of Lhermitte-Duclos (LD) disease (dysplastic gangliocytoma) and the diagnosis was confirmed following surgery. In this case, we emphasise the usefulness of MRI in the diagnosis of LD disease and consider the possible pathogenesis of the associated syringomyelia.