A snapshot of European neurosurgery December 2019 vs. March 2020: just before and during the Covid-19 pandemic

Background

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 or Covid-19), which began as an epidemic in China and spread globally as a pandemic, has necessitated resource management to meet emergency needs of Covid-19 patients and other emergent cases. We have conducted a survey to analyze caseload and measures to adapt indications for a perception of crisis.

Methods

We constructed a questionnaire to survey a snapshot of neurosurgical activity, resources, and indications during 1 week with usual activity in December 2019 and 1 week during SARS-CoV-2 pandemic in March 2020. The questionnaire was sent to 34 neurosurgical departments in Europe; 25 departments returned responses within 5 days.

Results

We found unexpectedly large differences in resources and indications already before the pandemic. Differences were also large in how much practice and resources changed during the pandemic. Neurosurgical beds and neuro-intensive care beds were significantly decreased from December 2019 to March 2020. The utilization of resources decreased via less demand for care of brain injuries and subarachnoid hemorrhage, postponing surgery and changed surgical indications as a method of rationing resources. Twenty departments (80%) reduced activity extensively, and the same proportion stated that they were no longer able to provide care according to legitimate medical needs.

Conclusion

Neurosurgical centers responded swiftly and effectively to a sudden decrease of neurosurgical capacity due to relocation of resources to pandemic care. The pandemic led to rationing of neurosurgical care in 80% of responding centers. We saw a relation between resources before the pandemic and ability to uphold neurosurgical services. The observation of extensive differences of available beds provided an opportunity to show how resources that had been restricted already under normal conditions translated to rationing of care that may not be acceptable to the public of seemingly affluent European countries.

Electronic supplementary material

The online version of this article (10.1007/s00701-020-04482-8) contains supplementary material, which is available to authorized users.

Reform of the 3rd cycle in surgery training

The main objectives of the reform of the 3rd cycle of medical studies in France that was instituted in 2017 after eight years of preparation, are to train future specialists in a consistent and equitable fashion and to replace the previous time-based qualification by training based on the progressive acquisition of skills. This reform was an opportunity for the 13 different French surgical specialty Colleges involved to share reflections on what a surgeon actually was and to define training in surgical sub-specialties. The current reform is well adapted to these specifications and has fostered training models that are consistent with each other. This article discusses the historical construction of this reform, what will change in the training of future surgeons, as well as some points that warrant caution. The third cycle reform has also triggered a reform of the second cycle, which is expected to come into force for the 2020 academic year. Its objective will be to eliminate the guillotine effect created by the National Classifying Examinations and to allow students to better understand and test their desire and skills for a given specialty. It will be up to these same surgical Colleges to determine how to do this for the sub-specialties of the "surgery" discipline.

Functional outcome 1 year after aneurysmal subarachnoid hemorrhage due to ruptured intracranial aneurysm in elderly patients

BACKGROUND

Population aging raises questions about extending treatment indications in elderly patients with aneurysmal subarachnoid hemorrhage (aSAH). We therefore assessed functional status 1 year after treatment.

METHODS

This study involved 310 patients, aged over 70 years, with ruptured brain aneurysm, enrolled between 2008 and 2014 in a prospective multicentre trial (FASHE study: NCT00692744) but considered unsuitable for randomisation and therefore analysed in the observational arms of the study: endovascular occlusion (EV), microsurgical exclusion (MS) and conservative treatment. The aims were to assess independence, cognition, autonomy and quality of life (QOL) at 1 year post-treatment, using questionnaires (MMSE, ADLI, IADL, EORTC-QLQ-C30) filled in by independent nurses after discharge.

RESULTS

The 310 patients received the following treatments: 208 underwent EV (67.1%), 54 MS (17.4%) and 48 were conservatively managed (15.5%). At 1 year, independence rates for patients admitted with good clinical status (WFNS I-III) were, according to the aneurysm exclusion procedure (EV, MS or conservative), 58.9%, 50% and 12.1% respectively. MMSE score was pathological in 26 of the 112 EV patients (23.2%), 10 of the 25 MS patients (40%) and 4 of the 9 patients treated conservatively (44%), without any statistically significant difference [Pearson's Chi² test, F ratio=4.29; P=0.11]. Regarding QoL, overall score was similar between the EV and MS cohorts, but significantly lower with conservative treatment.

CONCLUSION

Elderly patients in good clinical condition with aSAH should be treated regardless of associated comorbidities. Curative treatment (EV or MS) reduced mortality without increasing dependence, in comparison with conservative treatment.

Rupture limit evaluation of human cerebral aneurysms wall: Experimental study

BACKGROUND AND PURPOSE

Rupture risk of intracranial aneurysms is a major issue for public healthcare. A way to obtain an individual rupture risk assessment is a main objective of many research teams in the world. For many years, we have investigated the relationship between the mechanical properties of aneurysm wall tissues and the rupture risk. In this work, we try to go further and investigate rupture limit values.

METHODS

Following surgical clipping, a specific conservation protocol was applied to aneurysmal tissues in order to preserve their mechanical properties. Thirty-nine intracranial aneurysms (27 females, 12 males) were tested using a uniaxial tensile test machine under physiological conditions, temperature, and saline isotonic solution. These represented 24 unruptured and 15 ruptured aneurysms. Stress/strain curves were then obtained for each sample, and a fitting algorithm was applied following a Yeoh hyperelastic model with 2 parameters. Moreover, uniaxial tensile tests were conducted until rupture of samples to obtain values of stress and strain rupture limit.

RESULTS

The significant parameter a C₂ of the hyperelastic Yeoh model, allowed us to classify samples' rigidity following the terminology we adopted in previous papers (Costalat et al., 2011; Sanchez et al., 2013): Soft, Stiff and Intermediate. Moreover, strain/stress rupture limit values were gathered and analyzed thanks to the tissue rigidity, the status of the aneurysm (initially ruptured or unruptured) and the gender of the patient.

CONCLUSION

Strain rupture limit was found quite stable around 20% and seems not to be correlated with the status of the aneurysm (initially ruptured or unruptured), neither with the gender of the patient. However, stretch and stress rupture limit seems not to be independent on the rigidity. The study confirms that ruptured aneurysms mainly present a soft tissue and unruptured aneurysms present a stiff material.

Extradural resection of the anterior clinoid process: How I do it

BACKGROUND

The anterior clinoid process shares a close relationship with the optic canal, the internal carotid artery, the superior orbital fissure and the cavernous sinus. These structures may be involved in diseases whose surgical exposure requires prior clinoid process resection.

METHOD

Based on operative cases we describe the different steps of this surgical technique and illustrate our surgical procedure with a video. Dividing the orbito-temporal periosteal fold is a key-step in order to optimize the elevation of the periosteal dural layer at the level of the superior orbital fissure to expose the contours of the anterior clinoid process. The clinoid tip is removed after "debulking" the bony content inside the anterior clinoid process in order to leave only a thin shell of bony contour. The bony shell is then detached from the dura, twisted and pulled out. The indications and limitations of the technique are presented.

CONCLUSION

The extradural approach of the anterior clinoid process totally provides a full resection of the anterior clinoid process and safety for the paraclinoid space structures. Meticulous stepwise bony resection and optimized dura opening contribute to reduce the risk inherent to this technique.

Surgical anatomy of the jugular foramen

The jugular foramen (JF) is a canal that makes communication between the posterior cranial fossa and the upper neck for one third of the cranial nerves and for the main venous channel of the brain. From a lateral view, the JF is protected by multiple layers of muscles and by the outer surface of the petrous bone. Surgical exposure of the JF is usually justified by the removal of benign tumors that grow in this region. In the first part of the present study we describe the surgical anatomy of the JF Then, we detail the relevant points of a stepwise surgical progression of three lateral skull base approaches with a gradual level of exposure and invasiveness. The infralabyrinthine transsigmoid transjugular-high cervical approach is a conservative procedure that associates a retrolabyrinthine approach to a lateral dissection of the upper neck, exposing the sinojugular axis without mobilization of the facial nerve. In the second step, the external auditory canal is transsected and the intrapetrous facial nerve is mobilized, giving more exposure of the carotid canal and middle ear cavity. In the third step, a total petrosectomy is achieved with sacrifice of the cochlea, giving access to the petrous apex and to the whole course of the intrapetrous carotid artery. Using the same dissection of the soft tissues from a lateral trajectory, these three approaches bring solutions to the radical removal of distinct tumor extensions. While the first step preserves the facial nerve and intrapetrous neurootologic structures, the third one offers a wide but more aggressive exposure of the JF and related structures.

Two- and three dimensional measures of vestibular schwannomas and posterior fossa--implications for the treatment

BACKGROUND

There is no uniformly accepted method of reporting the size of vestibular schwannomas (VS) and to evaluate the individual tumour behaviour in the posterior fossa (PF). To help the treatment decision we investigated the VS and PF morphometry using a computerized method.

METHOD

Stereotactic fused CISS MR and CT scan images were obtained from 58 adult patients (31 males and 27 females) harbouring an unilateral VS (25 Koos II, 21 Koos III and 12 Koos IV). Using a Gammaplanworking station we screened for the following measures: anteroposterior (AP), craniocaudal (CC), transverse (T) and maximum (Max) diameters (Diam) of the intracisternal part of the tumour, VS and PF volumes.

FINDINGS

The Max Diam was the most accurate way to estimate the tumour volume (Spearman's rho >0.80). Among several parameters, the T Diam was the best measure to assess the brain shift (ROC analysis) with a cut off value at 14.5 mm (91.7% sensitivity and 93% specificity). VS volume and the ratio VS volume/PF volume were also efficient to predict a brain shift.

CONCLUSIONS

Max Diam and T Diam are bedside measured simple data of particular interest to respectively estimate the VS volume and predict the brain shift due to the tumour. The determination of cut-off values correlated to brain shift will provide guidelines at the time of the therapeutic decision between radiosurgical and microsurgical strategy.

Surgical anatomy of the petrous apex and petroclival region

Surgical exposure of the clivus, the ventral or lateral aspect of the brain stem, and all the intradural structures of the petroclival area remains difficult because of the presence of the petrous apex and peripetrous complex. However, a lateral skull base approach to the petroclival area is the most suitable approach if the lesion to be resected lies medial to the fifth nerve, in front of the acousticofacial bundles, extending towards the midline. The purpose of this study is to review the topographic anatomy of the petrous apex and peripetrous structures, with emphasis on the relationships important to the lateral approaches to the petroclival area. Such anatomical knowledge allows us to study the surgical technique, exposure, and pitfalls of the main lateral transpetrosal skull base approaches used to reach the petroclival area.

Relative indications for radiosurgery and microsurgery for acoustic schwannoma

The physical and biological principles underlying the use of radiosurgery for the treatment of vestibular schwannomas of up to 2.5 cm in diameter are reviewed together with the historical controversies that have surrounded its introduction. The results in terms of mortality, quality of life, preservation of facial movement and hearing, incidence of shunt-dependent hydrocephalus, cancer neogenesis and brain stem damage are compared in the Marseilles series of 600 microsurgical procedures and 830 Gamma knife procedures and with the peer-reviewed literature. The key principles of a steep profile to radiation exposure at the tumour margin, careful topographical planning of the radiation against the tumour shape to minimise the radiation dose to the cranial nerves and brain stem, early tumour swelling, tumour texture and national history of the tumour are analysed. Protocols for the management of unilateral schwannoma, Type II neurofibromatosis (both the Wishart and the Gardner types) and residual/recurrent tumours are presented. In summary, the growth of nearly 97% of vestibular schwannomas (up to 2.5 cm) is arrested by the Gamma knife, the facial nerve is preserved in almost all cases and hearing may be preserved at its pre-operative level in nearly 70% of cases without the complications of microsurgery.

Surgical anatomy of the infratemporal fossa using the transmaxillary approach

In this study we evaluated the ability of the transmaxillary route to expose the elements of the infratemporal fossa (ITF). Five adult cadaver heads were dissected on both sides, after making a paralateronasal incision. The maxillary branch of the trigeminal nerve served as a superior landmark to progress into the retroantral space and pterygopalatine fossa. The maxillary artery, lateral pterygoid muscle, pterygoid venous plexus, foramen rotundum and foramen ovale were identified. Distances between those elements and angle of approaches of the foramen ovale and foramen rotundum were measured in the horizontal plane. In all cases, the anterior loop of the maxillary artery and the sphenopalatine artery were located in the proximal retroantral fatty space and could be ligated without optic magnification. The maxillary nerve could be followed up to the foramen rotundum at a 44 mm mean distance from the opening. The mean angle of vision to the foramen rotundum was 31 degrees. Under the greater sphenoid wing and lateral to the pterygoid process, desinsertion and partial resection of the lateral pterygoid muscle were required to identify the pterygoid venous plexus and foramen ovale. The pterygoid venous plexus was organized as a compact network of channels between and superior to the muscle fibers; it was in close relation with the foramen ovale. Access to the foramen ovale was deep (mean 56 mm) and narrow (20 degrees). Our results indicate that the transmaxillary approach is a minimally invasive procedure that gives an appropriate window to the structures of the retroantral space and to the pterygomaxillary fissure and pterygopalatine fossa. Monitoring of the retropterygoid portion of the infratemporal fossa by this route is inadequate.

Long-term outcome after gamma knife surgery for secondary trigeminal neuralgia

OBJECT

This study was directed to evaluate the potential role of gamma knife surgery (GKS) in the treatment of secondary trigeminal neuralgia (TN). The authors have identified three anatomicoclinical types of secondary TN requiring different radiosurgical approaches.

METHODS

Pain control was retrospectively analyzed in a population of patients harboring tumors of the middle or posterior fossa that involved the trigeminal nerve pathway. This series included 53 patients (39 women and 14 men) treated using GKS between July 1992 and June 1997. The median follow-up period was 55 months. Treatment strategies differed according to lesion type, topography, and size, as well as visibility of the fifth cranial nerve in the prepontine cistern. Three different treatment groups were established. When the primary goal was treatment of the lesion (Group IV, 46 patients) we obtained pain cessation in 79.5% of cases. In some patients in whom GKS was not indicated for treatment of the lesion, TN was treated by targeting the fifth nerve directly in the prepontine cistern if visible (Group II, three patients) or in the part of the lesion including this nerve if the nerve root could not be identified (Group III, four patients). No deaths and no radiosurgically induced adverse effects were observed, but in two cases there was slight hypesthesia (Group IV). The neuropathic component of the facial pain appeared to be poorly sensitive to radiosurgery. At the last follow-up examination, six patients (13.3%) exhibited recurrent pain, which was complete in four cases (8.8%) and partial in two (4.4%).

CONCLUSIONS

The results of GKS regarding facial pain control are very similar to those achieved by microsurgery according to series published in the literature. Nevertheless, the low rate of morbidity and the greater comfort afforded the patient render GKS safer and thus more attractive.

[Recurrent acoustic neurinoma after complete surgical resection]

BACKGROUND

Mortality of acoustic neurinoma surgery is currently very low, well below the figures reported by the first surgeons. Morbidity has also declined with attempts at preserving the facial function and more recently hearing function. Long-term follow-up has demonstrated the well-known risk of recurrence after partial resection, but also evidenced a risk after complete resection.

PATIENTS AND METHODS

We reviewed two series of patients, the first including 40 patients treated and followed at the Timone Hospital since 1975 and the second including 97 operated patients who were followed by the ENT Federation over 8 to 16 years. We studied recurrence after partial and complete resection.

RESULTS

Recurrence rate was 20% after partial resection and 9.2% after complete resection.

DISCUSSION

The 20% recurrence rate after partial resection was similar to that reported in the literature. After total extirpation, our 9.2% recurrence rate appears well above the 1% reported by others. Although our series could have a bias due to the large number of patients lost to follow-up, the large population size and the fact that we had a majority of large tumors would suggest that recurrence rate is generally underestimated. An 8 to 10% rate appears to be closer to reality. Most recurrences were late, with a peak around 8 years. We did however observe recurrences as early as 1 year and as late as 20 years. Delay appears to be shorter after partial removal. A wide range of localizations were observed but two areas predominated: the internal auditory canal and the components of the acousticofacial pedicle, and to a lesser degree the brain stem. Most patients were asymptomatic. The principal manifestations were balance disorders or trigeminal nerve lesions, more rarely facial palsy. But these clinical signs came late and generally signaled a bulky tumor measuring more than 3 cm.

CONCLUSION

These findings lead us to insist on the need for radiological monitoring of all operated neurinomas irrespective of the initial surgery. MRI appears to be more accurate than computed tomography. Images must be interpreted carefully due to possible postoperative remodeling. For us, these observations point to the need for prolonged follow-up of at least 8 years, longer for young subjects, for all patients undergoing surgical resection of an acoustic neurinoma.

[Endolymphatic sac tumors]

Tumors of the endolymphatic sac are rare and can be found in patients with Von Hippel Lindau disease. They most often develop within the intrapetrosal part of the sac but can sometimes be located in the distal part. Their growth is slow and they spread in two directions: laterally toward the external and middle ear and in the direction of the jugular foramen and medially into the ponto-cerebellar angle. The symptoms are usually auditive, with a constant neurosensorial deafness of sudden onset in 50 % of cases and sometimes associated with a tinnitus and dizziness. The varieties with medial extension result in a cerebellopontine angle syndrome. Diagnosis is made by imaging (CT scan and MRI) that reveals a heterogeneous tumor between the lateral sinus and the internal auditory meatus, hypervascularized showing contrast, with cystic zones and associated with bone lysis. Histological examination of a papillary cystadenoma is performed and the differential diagnosis is essentially made with a papillary of the choroïd plexus. They require total surgical excision in order to avoid possible recurrence and can be performed by retrosigmoïd approach, or more ideally, by transpetrosal approach.

[Neurofibromatosis type 2. Preliminary results of gamma knife radiosurgery of vestibular schwannomas]

BACKGROUND AND PURPOSE

The aim of this study was to assess tolerance and efficacy of gamma knife radiosurgery on vestibular schwannomas for patients affected with neurofibromatosis type 2.

METHODS

Between July 1992 and December 1997, a gamma knife procedure was performed on 35 vestibular schwannomas affecting 27 patients (12 females and 15 males, mean age=27 years-old, range: 14-65). Fifteen of the patients were included in the Wishart subtype (severe form) and 12 patients in the Gardner subtype (mild form). This group of 27 patients represented 8,2% of the total group of vestibular schwannomas radiosurgically treated by our team. The mean tumor volume was 4,000 mm(3) (range: 400-14,400 mm(3)) and staging according to Koos classification was 9 stage 2 tumors (extension in the cerebellopontine angle), 19 stage 3 tumors (in contact with the brain stem or cerebellum) and 7 stage 4 tumors (compression of axial structures). The delivered mean marginal dose (50% isodose) was 13 Gy (range: 10-18 Gy). After the treatment, the mean clinical and radiological follow-up was 32 months (range: 6-70).

RESULTS

Twenty six (74%) of the treated tumors were controlled by the treatment (15 stabilizations and 11 regressions of the tumor volume) at last follow-up. One microsurgical removal was required in a growing stage 4 tumor and in 2 cases of growing stage 3 tumors. Three post-radiosurgical facial nerve deficits (9%) were observed, 2 of them were transient. According to the Gardner and Robertson classification, classes I (good) and II (serviceable) hearing were preserved at last follow-up in 57% of the patients having the same hearing level prior to the gamma knife.

CONCLUSIONS

Our experience confirms that tolerance of gamma knife radiosurgery compares favorably with microsurgery of bilateral vestibular schwannomas. This treatment should be restricted to small and medium growing tumors. Treatment strategy of neurofibromatosis type 2 patients should be planned by multidisciplinary experienced teams disposing of the whole armamentarium. A longer follow-up study is required to confirm the current results regarding the tumor control rate.

[Epidermoid cyst of the lateral ventricles]

A case of epidermoid cyst of the lateral ventricles is reported. The patient presented with a weakness of the left lower limb and neuropsychological disorders. The diagnosis was assessed by CT scan and MRI, and confirmed at the operation. The lesion has been largely removed through a transcallosal approach though incompletely. However the long term follow-up was uneventful. Twenty-nine cases of the literature have been reviewed.

[Dural metastases mimicking meningioma. Report of a case]

We report a case of dural metastasis, detailing the neuroradiologic and therapeutic aspects. The clinical presentation was limited to a progressive left hemiparesis. Post-contrast CT scan revealed a heterogeneous high-density mass of the right fronto-parietal convexity. MRI demonstrated dural involvement mimicking meningioma. Chest X-ray showed a right lung opacity, suggesting the diagnosis of dural metastasis. Surgical resection was performed. Histology confirmed the diagnosis of dural metastasis from a poorly differentiated carcinoma. Treatment was completed with radiotherapy and chemotherapy. Dural metastases are rarely reported. A review of the literature revealed principally 2 radiological aspects: hemorrhagic effusion and tumor mass. The pathophysiology of dural metastases is still a subject of debate. Two mechanisms have been put forward involving venous and arterial dissemination. As radiological aspects are confusing, the diagnosis of dural metastasis should be evoked in patients with spontaneous hemorrhagic subdural effusion or a tumor mass involving the dura mater.

[Lumbar canal stenosis caused by amyloidosis of the yellow ligament]

Symptomatic lumbar canal stenosis without bony stenosis has previously been described. We describe the pathological modifications of ligamentum flavum among such operated patients. Ten patients were prospectively included in this study. Their mean age was 74, ranges: from 52-90. Clinical manifestation was a radicular claudication (sciatic or crural). Neuroradiology confirmed in all cases the ligamentum flavum thickness as the main cause of the symptomatology. This feature was also confirmed operatively and complete resection of the ligamentum flavum was performed. Resolution of the radicular pain was obtained in all cases at last follow-up. Pathological examination of the ligamentum flavum displayed characteristic features of degenerative modifications and elastic fibers fragmentation caused by numerous amorphous deposits. The deposits were studied using red Congo staining, polarized light and immunostaining methods. Such technique showed evidence of amyloid origin of the deposits. Immunodetection was positive for the P component in the amyloid deposits and for beta-2-microglobulin in one case (chronic renal failure and hemodialysis). The deposits did not express antitransthyretin antibodies. In parallel, control ligamentum flavum were obtained from 10 operated patients affected by bony lumbar stenosis. Moderate degenerative features were observed but small amounts of amyloid deposits were found in only 3 of those cases, without thickening of the ligamentous structure. This study correlates the presence of thickened ligamentum flavum caused by amyloid deposition, with symptomatic non-osseous lumbar canal stenosis. Association with degenerative modifications of the spine in the studied cases is suggestive of a microtraumatic origin.

[Acoustico-facial cavernomas. Apropos of 2 surgically treated cases]

BACKGROUND

Acousticofacial cavernomas are rare lesions. Only 4 cases with a cerebellopontine extension have been reported previously whereas intrapetrous facial nerve cavernomas are well described in the otologic literature. In this paper, we describe two additional cases of acousticofacial cavernomas.

METHOD AND RESULTS

The two patients were operated via a translabyrinthine route with a preoperative diagnosis of vestibular schwannoma. In the first case, the lesion was confined in the internal auditory canal whereas the cavernoma extended into the cerebellopontine angle in the latter.

CONCLUSIONS

Diagnosis is suspected when facial nerve deficit strikingly reveals a small cerebellopontine angle lesion. MRI examination is not specific enough when the lesion is confined to the internal auditory canal. Treatment is based upon surgical removal although facial nerve impairment is often described as the main cause of postoperative morbidity.

Anterior lumbosacral dislocation: case report and review of the literature

BACKGROUND

Anterior lumbosacral dislocation is a rare traumatic anterior spondylolisthesis.

METHODS

We report a new case surgically treated and review the eight cases previously reported.

RESULTS

The mechanism of injury is hyperflexion-distraction. Neurological signs are inconsistent. Indirect radiological signs such as bilateral multiple transverse process fractures are strongly suggestive of the diagnosis. This complete soft tissue injury induces a definitive instability and requires an open reduction with posterior fixation.

CONCLUSIONS

Suspicion of lumbosacral dislocation requires a computed tomography scan exploration with multiplanar reconstructions. Early reduction is associated with neurologic recovery. However, prognosis is correlated with the initial neurologic status and the severity of other associated injuries.

Endolymphatic sac tumors: report of three cases

OBJECTIVE AND IMPORTANCE

We present three cases of endolymphatic sac tumors and review the previously published cases. Despite frequent extension to the cerebellopontine angle, these rare tumors have only recently been recognized by neurosurgeons.

CLINICAL PRESENTATION

A 26-year-old man developed a progressive hearing loss, revealing an intrapetrous retrolabyrinthine tumor on the right side. A 28-year-old woman experienced a left cerebellopontine angle syndrome, with a lytic intrapetrous mass extending into the cerebellopontine angle. A 38-year-old woman presented with an intracranial hypertension syndrome caused by a tumor of the jugular foramen.

INTERVENTION

For the first and second patients, the tumors originated from the operculum of the endolymphatic sac. Total removal was achieved, via a transpetrosal approach, in these two cases. No recurrence was detected after a 20-month follow-up period. For the third patient, the tumor originated from the distal part of the sac. Recurrence was observed 8 years after subtotal removal via a retrosigmoid route. Histological analysis revealed a papillary-cystic adenocarcinomatous pattern in all cases, without features of aggressiveness.

CONCLUSION

Endolymphatic sac tumors are locally invasive neoplasms characterized by bipolar intrapetrous and posterior fossa involvement. The anatomic complexity of the endolymphatic sac may explain the distinct patterns of extension of these tumors. Early radical surgery is related to good outcomes.

Expression of cell adhesion molecules in normal nerves, chronic axonal neuropathies and Schwann cell tumors

Cell adhesion molecules (CAMs) play a role in the normal development and regeneration of tissues as well as in the biological behaviour of tumors. We studied the immunohistochemical expression of various CAMs, such as neural cell adhesion molecule (NCAM), its polysialylated isoform (PSA-NCAM), epithelial (E-) cadherin, and beta1 integrins (alpha2beta1, alpha5beta1, alpha6beta1) in a series of frozen specimens of 10 normal nerves, 5 axonal neuropathies, 26 benign Schwannomas and 2 malignant peripheral nerve sheath tumors (MNST). NCAM was expressed by non-myelinating Schwann cells from normal nerves and overexpressed by Schwann cells from patients with chronic axonal neuropathies and Schwannomas. The expression was lower in MNST. Expression of PSA-NCAM was heterogeneously displayed by Schwann cells from the various tissues studied. Anti E-cadherin immunoreactivity was present in myelin sheath in normal nerves and axonopathies. It was expressed in some Schwannomas especially in vestibular Schwannomas. Integrins VLA alpha2 and VLA alpha6 were widely expressed by Schwann cells from normal nerves, axonal neuropathies and Schwannomas but their expression was low in MNST. VLA alpha5 was not expressed by Schwann cells from normal nerve and Schwannomas but present in chronic axonal neuropathies and MNST. In addition VLA alpha6 was strongly expressed by perineurial cells. These data show that CAMs have a characteristic pattern of expression in normal nerve. Also, some CAMs are always expressed by Schwann cells but the expression of others differs in normal nerves versus axonopathies or tumors, suggesting a role of the microcellular environment in the regulation of CAM expression. Schwannomas have different pattern of expression than MNST.

Cell-adhesion molecules in human meningiomas: correlation with clinical and morphological data

Integrins form a family of cell adhesion molecules. CD44 glycoproteins are found in a wide variety of isoforms; the most common, CD44s (standard) is widely distributed, and functions as an adhesion molecule. In this study, we have investigated immunohistochemically the distribution of some VLA integrins (alpha2, alpha5 and alpha6 chains of beta1 integrins) and CD44s in 44 meningioma specimens and normal arachnoid villi. Meningiomas were of meningothelial (16), transitional (13) and fibroblastic (15) subtypes. There were 13 grade I, 19 grade II and 12 grade III (27%). Immunoprecipitates were quantified by image analysis and correlated with clinical (age, sex, location) and morphological data (histological subtypes and grades). VLA alpha5 chain was expressed by normal arachnoid villi (mainly cap cells) and by 42 out of 44 meningioma specimens. Expression was lower in fibroblastic meningiomas (P=0.02). VLA alpha2 and alpha6 chains were not observed in normal arachnoid villi. VLA alpha2 was expressed by 15 meningiomas, VLA alpha6 by 10. Interestingly, meningiomas expressing either VLA alpha2 or alpha6 were usually of grade III (P< or =(0.05). CD44s was found on various parts of arachnoid villi and in all meningiomas although expression was higher in meningothelial and transitional than in fibroblastic (P< or =0.001). These results show that VLA alpha5 and CD44s are widely expressed by arachnoid villi and meningiomas, in contrast to VLA alpha2 and VLA alpha6. It was noted that high grade meningiomas (III) express VLA alpha2 and alpha6 suggesting that changes in integrin pattern expression are a feature of these meningiomas. Moreover, strong CD44s expression characterizes meningothelial and transitional meningiomas. Previous studies have shown that high NCAM expression is a feature of fibroblastic meningiomas whereas meningothelial and transitional meningiomas expressed mainly E-Cadherin, and that polysialylated NCAM expression was restricted to high grade meningiomas. Taken together these features suggest that each cell adhesion molecule has a characteristic pattern of expression according to meningioma subtype and grade. No correlation was seen between integrins and CD44s expression and clinical data.

[Primary spinal osteosarcoma. Apropos of a case]

We report a case of primary osteogenic sarcoma of the third lumbar vertebra, detailing the neuroradiologic and therapeutic aspects. The clinical presentation was limited to low back pain which radiated to the left thigh for 5 months. Lumbosacral spine roentgenograms revealed a sclerotic lesion of the left part of the body of the third lumbar vertebra. Treatment consisted of total vertebrectomy, chemotherapy completed with radiotherapy. Fourteen months after a complex combined treatment no recurrence was observed. A review of the literature highlighted the rarity of this tumor. Usually, patients with vertebral osteogenic sarcoma do poorly. Today, the therapeutic approach for these spinal tumors should use techniques developed in the treatment of osteosarcoma of the extremities because of their encouraging results.

[Primary spinal osteosarcomas]

The rarity of primary osteosarcoma of the spine led us to index the 66 reported cases published in literature. From this analysis a difference was found between spinal osteosarcoma and osteosarcoma of the extremities. Tumors of the spine appear to be two times more frequent in the male population in their thirties. The average period between the beginning of the symptoms and the first consultation is seven months. Back pain is permanent and localized to the affected vertebra. In 80 percent of the cases, neurological symptoms already exist at the stage of the diagnosis. Magnetic resonance imaging (MRI), computed tomography and standard X-ray remain complementary in the morphological analysis of this tumor. All the aspects from the lytic to sclerotic forms are noted, although the lytic form is common. Among spinal osteosarcoma, the lumbar vertebrae are the most frequently affected. Diagnosis can only be established by pathology, even though this may also lead to some errors. In all the reported cases surgery is used, but carcinological methodology is not possible and a complete removal of affected tissue is difficult, with this being achieved in only a quarter of the cases. Radiation therapy, when used, requires doses of 70 Gy to 80 Gy without any certitude of controlling the tumour and with high risks of post-radiation complications. Chemotherapy on its own, despite the use of high-dose methotrexate, only has a temporary effect due to partial action on the primary center. Twenty years ago, only twenty percent of all patients suffering from osteosarcoma lived beyond two years, with worse prognosis for spinal osteogenic sarcoma. Today, the therapeutic approach for spinal tumors uses techniques developed in the treatment of osteosarcoma of the extremities, which can now expect more than seventy percent of all patients to live beyond five years. Present day methods recommend a rapid confirmation of the diagnosis, and then a neoadjuvant chemotherapy followed by surgery to remove all the affected area. This strategy allows an evaluation of the tumor chemosensitivity and to adapt the treatment in consequence. The latest results of this treatment on spinal osteosarcoma appear to be encouraging.

Cauda equina paraganglioma with subsequent intracranial and intraspinal metastases

A case of cauda equina paraganglioma is described; subsequent intracranial and intraspinal metastases occurred after partial resection and adjunctive radiotherapy. Cerebrospinal fluid dissemination is a rare complication of spinal paragangliomas. Factors predictive of this unusual biological behaviour are discussed.

Cervical interbody xenograft with plate fixation: evaluation of fusion after 7 years of use in post-traumatic discoligamentous instability

STUDY DESIGN

This retrospective study analyzed clinical and radiologic follow-up evaluations of cervical arthrodesis where interbody xenograft combined with internal fixation was used for management of post-traumatic discoligamentous instability.

OBJECTIVES

To report results of use of xenograft to avoid the various disadvantages linked to the use of autologous or allogenous bone graft.

SUMMARY OF BACKGROUND DATA

Ligamentous instability of the cervical spine is unlikely to heal in a high proportion of cases, and surgical arthrodesis is usually indicated. Anterior arthrodesis has proved to be a safe procedure, but many problems are associated with the use of autograft or allograft. Given the great number of xenograft procedures, there are relatively few reports in the literature.

METHODS

A retrospective study analyzed a consecutive series of 52 patients presenting with post-traumatic discoligamentous instability of the cervical spine in which cervical interbody xenografts with plate fixations were done. Follow-up clinical evaluation for neck pain and radiologic evaluation for arthrodesis stability and xenograft fusion at various points in time were done.

RESULTS

The long-term results in 41 patients were satisfactory: no infectious complications, extrusion, fracture, loss of height, or resorption of the graft. Seventy-five percent fusion was seen before 9 months after surgery, and 100% fusion was seen 3-18 months after surgery (average, 7.4 months).

CONCLUSIONS

Interbody xenograft combined with a rigid plate fixation avoids the problems linked to autologous or allogenous bone graft and gives a safe and solid interbody fusion when arthrodesis is required in ligamentous instability of the cervical spine.

[Angiographically occult vascular malformations of the brain stem. Apropos of 25 cases]

Due to the current use of magnetic resonance imaging (MRI), angiographic occult vascular malformations (AOVM) located in the brain stem are frequently reported in the last ten years. The term AOVM is ambiguous and controvers. For, most of these lesions presented with MRI pattern of a cavernous angioma, but only few cases received pathological confirmation. In this location, the operative treatment while worthwhile could be hazardous indeed, so a conservative management is more commonly discussed first. However, the potential risk of rebleeding or poor clinical condition sometimes encourage a more aggressive decision. We report our experience in 25 patients (4 children and 21 adults) admitted between 1982 and 1994 with an AOVM located in the brain stem. In 17 patients, the cryptic vascular lesion was removed surgically. A cavernous angioma was strictly confirmed in only 8 cases. Conversely, 8 patients were managed conservatively. In the surgically treated group of patients, 10 improved their neurological deficit postoperatively, 2 patients remained unchanged, 3 patients worsened, and 2 patients died. The final outcome in 14 patients was evaluated after 51 months of mean follow-up (17 to 70 months). In 5 cases (35.7%) the result was excellent (no symptoms), 5 cases had a good result (normal activity with minimal residual disability), and 4 cases (28.5%) remained with severe permanent disability. In the non-surgically treated group of patients, the final outcome was evaluated after a mean follow-up period of 67 months (from 1 to 120 months). One patient experienced a rebleeding and remained severely disabled. Another patient had two bleeding episodes leaving only a minor facial numbness. Four patients were symptom-free, and the last case was lost for follow-up.

Crowned dens syndrome: a manifestation of hydroxy-apatite rheumatism

Crowned dens syndrome is defined as an association of acute cervical pain and calcifications in the peri-odontoid space. The authors report one case of this rare localization of hydroxy-apatite rheumatism and review 12 similar cases in the literature. This disease affects only adult females. Patients present with inflammatory signs, can be treated with non-steroid anti-inflammatory drugs and recover without sequela. Calcium pyrophosphate dihydrate deposition can also lead to this syndrome. Other perioodontoid calcifications and ossifications, usually asymptomatic, appear only as a radiologically crowned dens.

Popliteal artery entrapment syndrome. Anatomic and embryologic bases, diagnostic and therapeutic considerations following a series of 15 cases with a review of the literature

We report 15 examples of popliteal artery entrapment syndrome observed in 11 patients. The anatomical causes were as follows: in one case, the popliteal artery presented an aberrant course medially to the medial head of the gastrocnemius muscle. In 5 cases, there was a small fibrous band linking the medial head of the gastrocnemius muscle to the lateral condyle and crossing behind the popliteal artery; in 5 cases this anomaly was also found in association with an abnormally high and/or internal insertion of the medial head of gastrocnemius muscle. In the last 4 cases, there was a muscular insertion anomaly associated with muscular hypertrophy causing arterial compression. Arteriography performed in the 11 patients showed evocative signs of the diagnosis in all cases where the artery was patent. Two popliteal arteries were occluded. CT scan and MRI examination of the popliteal fossa enabled us to define the muscular origin of the popliteal compression. All of the patients were operated upon; two received a reversed saphenous bypass and all of the others were treated by liberation of the popliteal artery and/or vein by a posterior approach. Follow-up in all patients at long term showed good prognosis. All of the patients were able to take up their previous physical activities without sequelae. Our review of the literature, which is based on 374 cases of popliteal artery entrapment observed in 280 patients, made it possible to define the frequency of the various anomalies observed, their symptoms and the different therapeutic possibilities. The multiple anatomical classifications as well as the arterial and muscular embryology are also described.

Pneumocephalus after thoracotomy

BACKGROUND

Pneumocephalus is a well-known phenomenon in which a fistula between the thoracic cavity and the subarachnoid space is one of its rare etiologies.

METHODS

We report a new case of pneumocephalus after thoracotomy and review eight similar cases in the literature.

RESULTS

In all cases, an operation was carried out for an intrathoracic neoplasm located at the apex with chest wall invasion. In the presence of symptoms, the diagnosis of pneumocephalus and identification of the subarachnoid pleural fistula were differently supplied by radiographic and isotopic exams. In the follow-up, one patient was affected by meningitis and two patients died.

CONCLUSIONS

The occurrence of pneumocephalus must be considered when neurologic problems emerge after thoracotomy. It appears that if conservative treatment fails, surgical closure of the fistula via thoracic or neurosurgical approach is indicated.

Giant central neurocytoma with tetraventricular and extra-axial extension. Case report

The central neurocytoma is a recently recognized benign intraventricular tumour of young adults. The authors report a unique case of a panventricular neurocytoma with extension to the interpeduncular and prepontique cisterns which developed in a 35-year-old woman with a 7-year history of headaches and amenorrhea. They review the different pathological and topographical patterns of previously published neurocytomas and discuss the histogenesis of this rare tumour.

Surgical management of extracranial internal carotid artery aneurysms

Between 1980 and 1991, 13 of 1312 carotid artery reconstructions were performed for aneurysms of the extracranial internal carotid artery. The patients included 12 men and one woman, mean age 56 years. Postoperative aneurysms and aneurysms involving the common carotid artery were excluded from the study. In six cases, the upper part of the aneurysm was higher than a line joining the mandibular to the tip of the mastoid process. Six aneurysms were atherosclerotic, two post-traumatic, four dysplasic and one post-traumatic and atherosclerotic. Nine patients had focal neurological symptoms (seven hemispherical, two ocular), one presented with cranial nerve compression, two had non-hemispherical symptoms and one was symptom-free. Surgical reconstruction was achieved by 12 venous grafts and one aneurysmorrhaphy. A conventional cervical approach was used in seven cases; in four cases subluxation of the mandible with resection of the posterior belly of the digastric muscle and division of the styloid process and its attached muscles was used. An infratemporal approach with release of the 7th nerve and opening up of the first portion of the carotid canal was used in two patients. There were no deaths or strokes but two patients had a transient ischaemic attack. In four cases, a cranial nerve palsy developed; one involving the 9th nerve did not recover. Patency was assessed by postoperative angiography in all cases. Mean (range) follow-up was 46 (4-126) months. One patient died after 2 years as a result of myocardial infarction. One patient had a transient ischaemic attack during the 2nd postoperative year. All survivors were assessed in January 1992, when all reconstructed arteries were patent.