Franco Faccioli

Surgery for intramedullary spinal cord tumors: the role of intraoperative (neurophysiological) monitoring

In spite of advancements in neuro-imaging and microsurgical techniques, surgery for intramedullary spinal cord tumors (ISCT) remains a challenging task. The rationale for using intraoperative neurophysiological monitoring (IOM) is in keeping with the goal of maximizing tumor resection and minimizing neurological morbidity. For many years, before the advent of motor evoked potentials (MEPs), only somatosensory evoked potentials (SEPs) were monitored. However, SEPs are not aimed to reflect the functional integrity of motor pathways and, nowadays, the combined used of SEPs and MEPs in ISCT surgery is almost mandatory because of the possibility to selectively injury either the somatosensory or the motor pathways. This paper is aimed to review our perspective in the field of IOM during ISCT surgery and to discuss it in the light of other intraoperative neurophysiologic strategies that have recently appeared in the literature with regards to ISCT surgery. Besides standard cortical SEP monitoring after peripheral stimulation, both muscle (mMEPs) and epidural MEPs (D-wave) are monitored after transcranial electrical stimulation (TES). Given the dorsal approach to the spinal cord, SEPs must be monitored continuously during the incision of the dorsal midline. When the surgeon starts to work on the cleavage plane between tumor and spinal cord, attention must be paid to MEPs. During tumor removal, we alternatively monitor D-wave and mMEPs, sustaining the stimulation during the most critical steps of the procedure. D-waves, obtained through a single pulse TES technique, allow a semi-quantitative assessment of the functional integrity of the cortico-spinal tracts and represent the strongest predictor of motor outcome. Whenever evoked potentials deteriorate, temporarily stop surgery, warm saline irrigation and improved blood perfusion have proved useful for promoting recovery, Most of intraoperative neurophysiological derangements are reversible and therefore IOM is able to prevent more than merely predict neurological injury. In our opinion combining mMEPs and D-wave monitoring, when available, is the gold standard for ISCT surgery because it supports a more aggressive surgery in the attempt to achieve a complete tumor removal. If quantitative (threshold or waveform dependent) mMEPs criteria only are used to stop surgery, this likely impacts unfavorably on the rate of tumor removal.

Surgical treatment of spinal dural arterio-venous fistulae: long-term results and analysis of prognostic factors.

SummaryBackground. Spinal dural arterio-venous fistulae (SDAVF) are slow-flow extramedullary vascular lesions which account for 75–80% of all spinal vascular malformations. At present there is no agreed view with regard to the best therapeutic option being surgical or endovascular, and several reports favour one or other form of management. This is so because of lack of consistent literature, as well as knowledge, concerning the long-term clinical outcome of the patients. The objective of this study is to retrospectively analyse the results obtained with patients operated for a SDAVF at the Department of Neurosurgery of Verona during a 15-year period and to evaluate possible prognostic factors related to neurological outcome. Patients and methods. Between January 1987 and May 2002, 29 patients with SDAVF were operated at the Department of Neurosurgery of Verona. For 25 of these patients we were able to obtain a clinical follow-up using telephone interviews. The patients were evaluated with the Aminoff and Logue’s scale and subsequently stratified into three classes of disability. An overall score (gait and micturition, G + M) of 0–3 indicates a mild disability, a score between 4 and 5 indicates a moderate disability and a score between 6 and 8 a severe disability. All patients underwent surgical treatment which was mainly the first therapeutic option. Following surgery, the patients were re-evaluated with the same neurological scale. We also investigated with statistical analysis the possible impact on clinical outcome of the major clinical, neuroradiological and surgical variables. Results. The epidemiological, clinical, radiological and pathological features of our group of patients are very similar to those previously described in the literature. For 10 patients surgery consisted simply of the interruption of the intradural arterialised draining vein (with or without closure of the small extradural arterial afferents), whereas in the remaining 15 patients coagulation or excision of the fistolous dura was also accomplished. At the last follow-up (mean 7.3 years; in 19 patients longer than 5 years), 10 patients had improved (40%), 11 were stable (44%) and 4 had deteriorated (16%). We determined that only the pre-operative neurological status, described by the G value in the Aminoff and Logue’s scale and the class of disability, had an impact on clinical outcome. Conclusions. This retrospective study confirms that the surgical treatment results of SDAVF are satisfactory even if evaluated after many years. Given these results, and in accordance with the majority of the literature, we concur that surgery should be the first choice treatment for these spinal vascular lesions in order to avoid a dangerous delay and consequently further neurological deterioration. In our group of patients the only prognostic factor statistically related to clinical outcome was the pre-treatment neurological status, particularly the grade of paraparesis and the class of disability.

Intraneural cavernous malformation of the cauda equina

Spinal cavernous angiomas are rare vascular malformations occurring mainly in the vertebral body with or without an extradural extension. Only 3-5% of these lesions are entirely located in the spinal canal where they can occupy an extradural, intradural-extramedullary or intramedullary position. We present a 75-year-old woman with signs and symptoms of multiple lumbar radiculopathy. The lumbosacral MRI showed an intradural cauda equina lesion with heterogeneous contrast enhancement that was subsequently radically removed through an L3-L4 laminectomy. The microscopic appearance was suggestive of cavernous angioma with intraneural growth. Clinical, radiological, and surgical features of this unusual lesion (to date, only 12 cases are reported) are discussed.

Late deterioration of neurologic function in patients surgically treated for spinal dural arteriovenous fistulas

BACKGROUND A limited number of reports on the long-term neurologic outcome of patients with SDAVFs treated by surgery and/or embolization are available in the literature. The aim of our study is to neurologically evaluate these patients at 2 different follow-up stages, after surgery, to demonstrate a possible late neurologic deterioration after an initial improvement. METHODS Between January 1987 and May 2002, 29 patients with SDAVFs were operated on at the Verona Department of Neurosurgery. In this group we retrospectively identified 16 patients who had 2 different clinical follow-ups, at a mean of 4.5 and 9.2 years, respectively. We compared their neurologic status using the ALS. All these data were obtained from clinical charts and phone interviews. RESULTS The epidemiologic, clinical, and radiologic features of our group of patients are very similar to those previously described in the literature. Comparing the global clinical status between the 2 different follow-up stages, we observed a late deterioration in 8 cases (50%). A worsening of the mean G and M values of the ALS was also noted. Spinal angiography and contrast-enhanced MRI did not show any signs of recurrence of the fistula. CONCLUSIONS Our study confirms the possible occurrence of a late clinical deterioration in as many as 50% of patients surgically treated for a SDAVF. We deem that the main pathophysiologic mechanism underlining this phenomenon is a gradual and irreversible decline in spinal function related to those hemodynamic modifications induced by the fistula and to the persistence of a state of anatomofunctional deficiency of the spinal venous drainage.

Cauda equina syndrome caused by lumbosacral epidural lipomatosis. A case report

Section of Neurology, Department of Neurological, Neuropsychological, Morphological and Motor Sciences, University of Verona, Verona, Italy Department of Pathology, Azienda Ospedaliera Universitaria Integrata-Ospedale Civile Maggiore, Verona, Italy Department of Radiology, University of Verona, Verona, Italy Department of Neurosurgery, University Hospital, Verona, Italy IRCCS Fatebenefratelli, Brescia, Italy