Michele Ferrante

Prognostic relevance of the postoperative evolution of intramedullary spinal cord changes in signal intensity on magnetic resonance imaging after anterior decompression for cervical spondylotic myelopathy

OBJECT Areas of intramedullary signal intensity changes (hypointensity on T1-weighted magnetic resonance [MR] images and hyperintensity on T2-weighted MR images) in patients with cervical spondylotic myelopathy (CSM) have been described by several investigators. The role of postoperative evolution of these alterations is still not well known. METHODS A total of 47 patients underwent MR imaging before and at the end of the surgical procedure (intraoperative MR imaging [iMRI]) for cervical spine decompression and fusion using an anterior approach. Imaging was performed with a 1.5-tesla scanner integrated with the operative room (BrainSuite). Patients were followed clinically and evaluated using the Japanese Orthopaedic Association (JOA) and Nurick scales and also underwent MR imaging 3 and 6 months after surgery. RESULTS Preoperative MR imaging showed an alteration (from the normal) of the intramedullary signal in 37 (78.7%) of 47 cases. In 23 cases, signal changes were altered on both T1- and T2-weighted images, and in 14 cases only on T2-weighted images. In 12 (52.2%) of the 23 cases, regression of hyperintensity on T2-weighted imaging was observed postoperatively. In 4 (17.4%) of these 23 cases, regression of hyperintensity was observed during the iMRI at the end of surgery. Residual compression on postoperative iMRI was not detected in any patients. A nonsignificant correlation was observed between postoperative expansion of the transverse diameter of the spinal cord at the level of maximal compression and the postoperative JOA score and Nurick grade. A statistically significant correlation was observed between the surgical result and the length of a patients clinical history. A significant correlation was also observed according to the preoperative presence of intramedullary signal alteration. The best results were found in patients without spinal cord changes of signal, acceptable results were observed in the presence of changes on T2-weighted imaging only, and the worst results were observed in patients with spinal cord signal changes on both Tl- and T2-weighted imaging. Finally, a statistically significant correlation was observed between patients with postoperative spinal cord signal change regression and better outcomes. CONCLUSIONS Intramedullary spinal cord changes in signal intensity in patients with CSM can be reversible (hyperintensity on T2-weighted imaging) or nonreversible (hypointensity on T1-weighted imaging). The regression of areas of hyperintensity on T2-weighted imaging is associated with a better prognosis, whereas the T1-weighted hypointensity is an expression of irreversible damage and, therefore, the worst prognosis. The preliminary experience with this patient series appears to exclude a relationship between the time of signal intensity recovery and outcome of CSM.

Magnetic resonance imaging in Posterior Reversible Encephalopathy Syndrome: report of three cases and review of literature

IntroductionEclampsia is one of the main causes of Posterior Reversible Encephalopathy Syndrome (PRES) a recent clinico-neuroradiological entity represented by characteristic MR findings of a symmetric bilateral subcortical/cortical hyperintensity in T2-weighted images, more often in parieto-occipital lobes, accompanied by clinical neurological alterations. Neuroradiological and clinical alterations are commonly completely reversible although ischemic evolution has been described. The pathophysiology is still a matter of debate. Specific magnetic resonance (MR) techniques, such as FLAIR (fluid attenuated inversion recovery) and DWI (diffusion weighted images) sequences, have improved the ability to detect subcortical/cortical lesions and helped to clarify the underlying pathophysiological mechanism of cerebrovascular involvement, which results important for an appropriate therapeutic decision.Case report and discussionWe report the MR imaging findings of three patients with eclampsia and PRES as well as a careful review of literature.

Role of magnetic resonance tractography in the preoperative planning and intraoperative assessment of patients with intra-axial brain tumours

PurposeThis study was conducted to assess the possibility of identifying precise white matter tracts situated in proximity to intracranial tumours, to define the anatomical and topographical relations between the same white matter tracts and the tumour, to verify the possibility of integrating tractographic images in the context of a package of three-dimensional anatomical images to send to the neuronavigation system, to assess the impact of this information on surgical planning, and to analyse, both pre-and postoperatively, the patient’s clinical conditions as an index of the functional integrity of the fibres themselves.Materials and methodsTwenty-five patients underwent diffusion tensor study prior to neurosurgery. With the use of dedicated software, relative colour maps were obtained and the trajectories of the white matter tracts adjacent to the tumour were reconstructed in three dimensions. These were then processed for preoperative planning. Planning, which was performed with the neuronavigator, was based on analysis of the location of the course of the main white matter tracts adjacent to the lesion (pyramidal tract, optic radiation and arcuate fasciculus). Two neurosurgeons were asked whether the tractography images had modified the access and/or intraoperative approach to the tumour. All patients were clinically assessed both pre-and postoperatively 1 month after the procedure to define the presence of symptoms related to the involvement of the white matter tracts studied and therefore to assess the integrity of the fibres after the operation.ResultsIn one patient, the tumour was situated away from all the tracts studied and did not compress them in any way. Overall, 40/75 tracts studied had no anatomical relation with the tumour, were not displaced by the tumour or could not be visualised in their entire course. Analysis of the remaining 35 white matter tracts led to an a priori change in the surgical approach for corticotomy in four patients (16%), with no disagreement between the two neurosurgeons and an impact on the extent of resection during surgery in 17 (68%), thus an overall impact on the surgical procedure in 80% of cases. Eight patients showed no symptoms related to the involvement of the white matter tracts studied. In the remaining 17 patients, the symptoms were related to involvement of the pyramidal tract, arcuate fasciculus or optic radiation. At 1-month follow-up, one previously asymptomatic patient reported a speech disorder (transcortical sensory dysphasia); in the remaining 24, symptoms remained unchanged, with a tendency to improvement in 14/17 with symptoms related to involvement of white matter tracts studied.ConclusionsMagnetic resonance (MR) tractography offers the neurosurgeon an anatomical panoramic view that can improve surgical planning for the resection of intracranial tumours. Despite the high incidence of cases in which the lesion is responsible for changes that hinder the reconstruction of white matter tracts, the technique can change the surgical approach for corticotomy, defines the extent of resection and leads to some change in the procedure in 80% of cases. The improvement of pre-existing symptoms and the absence of new symptoms in the postoperative phase, in our opinion, confirms the value of the technique.RiassuntoObiettivoValutare la possibilità di identificare definiti fasci di sostanza bianca localizzati in prossimità di un tumore cerebrale; definire le relazioni anatomiche e topografiche tra gli stessi fasci di sostanza bianca e il tumore; verificare la possibilità di integrare le immagini trattografiche nell’ambito di un pacchetto di immagini anatomiche tridimensionali da inviare a un sistema di neuronavigazione; valutare l’impatto di queste informazioni sulla programmazione chirurgica e analizzare, prima e dopo l’intervento chirurgico, le condizioni cliniche dei pazienti, come indici di integrità funzionale delle fibre stesse.Materiali e metodiVenticinque pazienti, che avevano preventivamente eseguito uno studio del tensore di diffusione, sono stati successivamente sottoposti a intervento neurochirurgico. Mediante un software dedicato, sono state ottenute le relative mappe colorimetriche e ricostruite in tre dimensioni le traiettorie dei fasci di sostanza bianca adiacenti alla neoformazione che sono state elaborate per la pianificazione preoperatoria. La pianificazione, effettuata mediante il neuronavigatore, si è basata sull’analisi della localizzazione e del decorso dei principali fasci di sostanza bianca adiacenti la lesione (fascio cortico-spinale, radiazione ottica e fascicolo arcuato). È stato chiesto a due neurochirurghi se e come la disponibilità della trattografia avesse modificato l’accesso e/o l’approccio intraoperatorio alla neoplasia. Tutti i pazienti sono stati valutati clinicamente sia in fase pre-che post-operatoria, a 1 mese dall’intervento, per definire la presenza di sintomi riferibili a un coinvolgimento dei fasci mielinici oggetto dello studio e verificare quindi, dal punto di vista clinico, l’integrità degli stessi in seguito all’intervento.RisultatiIn un paziente il tumore era localizzato a distanza da tutti i fasci considerati e non determinava sugli stessi effetti compressivi. Globalmente, dei 75 fasci considerati, 40 non avevano rapporto anatomico con il tumore, non venivano dislocati dallo stesso o non risultavano visualizzabili in tutto il loro decorso. L’analisi dei restanti 35 fasci di sostanza bianca considerati ha determinato una modifica a priori dell’approccio chirurgico di corticotomia in 4 pazienti (16%) senza casi di discrepanza nel giudizio tra i due neurochirurghi e un impatto sulla definizione dei limiti di resezione durante l’intervento in 17 (68%), risultando complessivamente di impatto sulla procedura chirurgica nell’80% dei casi. Otto pazienti non mostravano sintomi riferibili a un coinvolgimento dei fasci mielinici oggetto dello studio. Nei restanti 17 i sintomi erano riferibili a un coinvolgimento del fascio piramidale, arcuato o della radiazione ottica. Al controllo a 1 mese un paziente, precedentemente asintomatico, riferiva un disturbo del linguaggio a tipo disfasia sensoriale; nei restanti 24 la sintomatologia era invariata con tendenza al miglioramento in 14 dei 17 pazienti sintomatici per coinvolgimento dei fasci mielinici segnalati.ConclusioniLa tecnica della trattografia con RM offre al neurochirurgo una nuova panoramica anatomica che permette una migliore pianificazione della procedura chirurgica di resezione di patologia cerebrale. Nonostante l’elevata incidenza di casi in cui la patologia determina modificazioni che inficiano la possibilità di ricostruire i fasci di sostanza bianca, la tecnica modifica l’approccio chirurgico di corticotomia, consente di definire i limiti di resezione e determina globalmente un cambiamento dell’intervento nell’80% dei casi. Il miglioramento della sintomatologia pre-esistente e l’assenza di nuovi sintomi in fase post-operatoria conferma, a nostro avviso, la sua validità.

Role of contrast-enhanced MR venography in the preoperative evaluation of parasagittal meningiomas

Parasagittal meningiomas (PSM) may pose a difficult surgical challenge since venous patency and collateral anastomoses have to be clearly defined for correct surgical planning. The aim of this study was to assess the diagnostic value of contrast-enhanced (CE) magnetic resonance venography (MRV) in the preoperative evaluation of venous infiltration and collateral venous anastomoses in patients with PSM. CE-MRV was compared with phase-contrast (PC) magnetic resonance (MR) angiography, conventional angiography (when available), and surgery as a reference. Twenty-three patients undergoing surgery for meningiomas located adjacent to the superior sagittal sinus were prospectively evaluated. All the patients underwent both conventional MR examination and MRV. This was performed by means of PC and CE techniques. Both sets of angiograms (CE and PC) were evaluated by two expert neuroradiologists to assess (1) patency of the sinus (patent/occluded), (2) the extent of occlusion (in centimeters), and (3) the number of collateral anastomoses close to the insertion of the meningioma. Eight patients underwent digital subtraction angiography (DSA). All patients were operated on, and intraoperative findings were taken as the gold standard to evaluate the diagnostic value of MRA techniques. PC-MRV showed a flow void inside the sinus compatible with its occlusion in 15 cases, whereas CE-MRV showed the sinus to be occluded in five cases. CE-MRV data were confirmed by surgery, showing five patients to have an occlusion of the superior sagittal sinus. The PC-MRV sensitivity was thus 100% with a specificity of 50%. In those cases in which both MRV techniques documented occlusion of the sinus, the extent of occlusion was overestimated by PC compared with CE and surgery. CE-MRV depicted 87% of collateral venous anastomoses close to the meningioma as subsequently confirmed by surgery, while PC showed 58%. In the preoperative planning for patients with meningiomas located close to a venous sinus, CE-MRV provides additional and more reliable information concerning venous infiltration and the presence of collateral anastomoses compared with PC sequences.

Fiber density index, fractional anisotropy, adc and clinical motor findings in the white matter of patients with glioblastoma.

Whether fractional anisotropy (FA), apparent diffusion coefficient (ADC), and fiber density index (FDi) values differ in the white matter close to glioblastomas of both symptomatic and asymptomatic patients was investigated. Twenty patients with glioblastomas underwent magnetic resonance imaging study. The FDi, FA and ADC values were calculated in areas of white matter in close proximity to the tumor (perWM) and encompassing fibers of cortico-spinal tract and in the contralateral normal-appearing white matter (nWM). The clinical compromise of the cortico-spinal tract was graded using Brunnstrom’s criteria. FA and FDi were significantly decreased and ADC increased in perWM compared with the contralateral. Mean FDi, FA, and ADC values comparing perWM and nWM in symptomatic patients showed similar differences. Comparing the perWM of symptomatic and asymptomatic patients, mean FDi and ADC values were lower in symptomatic patients than in asymptomatic ones. A positive correlation was found between the clinical score (CS) and, separately, FDi, FA and ADC per WM values. In a multiple stepwise regression among the same factors, only the ADC of perWM values showed a positive correlation with the CS. An increased ADC plays a major role in reducing the number of fibers (reduced FDi) in symptomatic patients.

Selective White Matter Involvement in a Patient with Late Onset Krabbe Disease: MR, MR Spectroscopy, and Diffusion Tensor Study

The most frequent type of Krabbe disease has an infantile onset. Unusual slowly progressive adult forms have also been described. We described a different involvement of white matter tracts where magnetic resonance signal alterations were evident in a case of a patient affected by late‐onset form of disease.

Measurement of Cerebrospinal Fluid Flow: Technique Validation in a Patient with Idiopathic Normal Pressure Hydrocephalus

This study aimed to assess anatomical and functional changes disclosed by magnetic resonance imaging in a patient with suspect normal pressure hydrocephalus following surgical third ventriculostomy with placement of a ventriculoperitoneal shunt. The patient was investigated by phase contrast sequences to calculate CSF flow in the Sylvian aqueduct before and after the two surgical procedures. In addition, T1-weighted volumetric MPRAGE images were acquired using voxel-based morphometry to study any changes in size of the ventricular system and CSF in the subarachnoid spaces before and after surgery. CSF flow measurements were closely correlated with the patients clinical course, increased CSF flow coinciding with worsening symptoms, and a decrease in flow noted after surgery. There were no significant changes in the CSF volumes analyzed. Phase contrast technique proved reliable and effective for the purposes of diagnosis and long-term follow-up in patients with suspect normal pressure hydrocephalus eligible for surgery