Minimally invasive spine surgery in spinal infections.

Infections of the spine have been a constant throughout history. At present there are infections in the spine fostered in part by the same advances in medicine: there are a lot of immunocompromised patients, the life expectancy of patients with chronic diseases is augmented and the increasing number of complex spinal surgeries can result in secondary infection. In this review the main types of infection of the spine and its treatment highlighting techniques in minimally invasive surgery are discussed. Spontaneous pyogenic and nonpyogenic spine infections as well as iatrogenic infections can be treated in a different manner depending on its extension, location and microorganism involved. We will review the use and the indication of percutaneous image-guided techniques, endoscopic and microsurgical techniques with or without use of tubular retractors. We conclude that techniques in minimally invasive surgery in spine infections are safe, effective and have benefits in morbidity of the approach and subsequent patient recovery.

Inactivation of the DNA-repair gene MGMT and the clinical response of gliomas to alkylating agents.

BACKGROUND: The DNA-repair enzyme O6-methylguanine-DNA methyltransferase (MGMT) inhibits the killing of tumor cells by alkylating agents. MGMT activity is controlled by a promoter; methylation of the promoter silences the gene in cancer, and the cells no longer produce MGMT. We examined gliomas to determine whether methylation of the MGMT promoter is related to the responsiveness of the tumor to alkylating agents. METHODS: We analyzed the MGMT promoter in tumor DNA by a methylation-specific polymerase-chain-reaction assay. The gliomas were obtained from patients who had been treated with carmustine (1,3-bis(2-chloroethyl)-1-nitrosourea, or BCNU). The molecular data were correlated with the clinical outcome. RESULTS: The MGMT promoter was methylated in gliomas from 19 of 47 patients (40 percent). This finding was associated with regression of the tumor and prolonged overall and disease-free survival. It was an independent and stronger prognostic factor than age, stage, tumor grade, or performance status. CONCLUSIONS: Methylation of the MGMT promoter in gliomas is a useful predictor of the responsiveness of the tumors to alkylating agents.

Uniportal endoscopic superior thoracic sympathectomy.

OBJECTIVE: A retrospective study presenting our experience with upper thoracic endoscopic sympathectomy in patients with primary palmar hyperhidrosis. METHODS: One hundred patients (46 women and 54 men) underwent bilateral uniportal endoscopic thoracic sympathectomy since January 1, 1995. Age distribution ranged from 12 to 54 years (mean, 23.4 yr). RESULTS: Sympathectomy on both sides was accomplished within 30 minutes in a single stage. Ninety-six patients (96%) had an uneventful postoperative course and were discharged the following day. Four patients with residual hemothorax required intercostal drainage and were discharged on the third postoperative day. Ninety-six patients were completely satisfied with immediate and permanent relief of palmar perspiration. Compensatory hyperhidrosis was the major complication, which was usually mild and tolerable after reassurance. In only eight patients (8%) was the compensatory hyperhidrosis considered bothersome, requiring treatment with aluminum chloride in ethanol solution at 25%. There was no mortality. Recurrence of palmar hyperhidrosis has been noticed in five patients (5%) during the follow-up period (range, 2-56 mo; mean, 12 mo). At the time of reoperation, a remaining branch of the sympathetic chain could be observed and coagulated. CONCLUSION: We consider thoracoscopic sympathectomy to be a simple, safe, and effective method for treating palmar hyperhidrosis. It is an effective method for treating patients with palmar hyperhidrosis, with a shorter operation time, fewer hospital days, and a better cosmetic result, as compared with the open approaches.

Operative monitoring of hand and axillary temperature during endoscopic superior thoracic sympathectomy for the treatment of palmar hyperhidrosis.

OBJECTIVE: To find out how much the temperature in the palm rises after upper thoracic sympathectomy for palmar hyperhidrosis, and correlate the temperature with the outcome. DESIGN: Retrospective study. SETTING: University hospital, Spain. SUBJECTS: 73 patients (34 women and 39 men, age range 16-42 years, mean 26) who were operated for palmar hyperhidrosis between 1 January 1995 and 31 December 1997. INTERVENTIONS: Bilateral thoracic endoscopic sympathectomy during which the temperature was monitored on the skin of both axillae and thenar eminences, and in the oesophagus. MAIN OUTCOME MEASURES: Morbidity, alleviation of hyperhidrosis, recurrence rate, and differences in temperature postoperatively. RESULTS: There was minor bleeding during operation in 25 cases (34%), but in only 4 was it sufficient to require insertion of a drain; 2 patients developed transient Homer's syndrome; but the most common complication was compensatory hyperhidrosis (n = 52, 71%). In only 5 was this other than mild and required treatment with aluminium chloride in ethanol 25%. Palmar hyperhidrosis was alleviated in all cases, axillary sweating was considerably improved, and there was improvement in the feet in 56 (77%). There were 5 recurrences, all on the right side, during a mean follow up of 9 months (range 2-36), but in no case was the sweating severe. In almost all cases the temperature of the palm was less than that of the axilla before operation by a mean (SD) of 0.9 (0.3) degrees C. The rise in temperature varied from 1.7 (0.4) degrees C to 2.6 (0.4) degrees C. In the 5 patients who developed recurrences the increase was less (0.5 (0.4) degrees C). CONCLUSION: Thoracic endoscopic sympathectomy is safe, simple, and effective in treating palmar hyperhidrosis that has not responded to conservative treatment. Intradermal monitoring is an accurate and cost-effective way of monitoring temperature during operation. Although it is essential to achieve a rise in temperature of 1 degrees C, our most important finding was that the final temperature in both hands and axillae should be above 35 degrees C and as near as possible to 36 degrees C.

Experimental study following inactive implantation of an auditory brain stem implant in nonhuman primates.

We report changes in the cochlear nuclei (CNs) after 3 months of bilateral auditory deafferentation and simultaneous unilateral implantation of a dummy auditory brain stem implant (ABI) in 6 nonhuman primates (Macaca fascicularis). These specimens were compared to CNs of 9 controls and 7 bilaterally deafferented animals without implantation. The ABI array consists of 3 platinum electrodes mounted on a silicone pad with the back side covered with Dacron. No migration of the ABI was observed. All deafferented animals showed astrocytic reorganization in the CNs. Histologic changes consisted of superficial reactions around the implant, with formation of fibrillar bundles of fusiform cells, and the presence of giant cells close to the Dacron. Other findings were related to surgical trauma. The dummy ABI did not itself provoke serious adverse reactions in the CNs. Our observations support the possibility of ABI reimplantation surgery.

Auditory brainstem implantation in primates: lessons for human surgery and application.

We report on the surgical technique for surface electro-auditory prosthesis (EAP) implantation, pathological changes occurring at the cochlear nucleus complex (CNC), and its relation with electrical stimulation. Fourteen Macaca fascicularis were operated upon for a translabyrinthine bilateral auditory neurectomy, and simultaneous unilateral EAP implantation. Six animals were not stimulated, and the remaining eight were connected to an external active device. Stimulation was planned for 1000 hours. Biotolerance to the materials was adequate without significant reactions in the CNC surface, but an ependymal reaction. Lesions attributed to surgical trauma were also found. Two animals being stimulated could not complete the planned course due to cable break or EAP extrusion. One stimulated animal developed an asymptomatic brainstem abscess. A good knowledge of CNC topography is required to avoid surgical trauma. Externally connected devices may facilitate extrusion of the EAP or ascending infections.

[Auditory brain stem potentials evoked by electrical stimulation of cochlear nuclei during central auditive implant setting]. / Potenciales auditivos troncoencefálicos evocados por la estimulación eléctrica de los núcleos cocleares durante la colocación de implantes auditivos centrales.

INTRODUCTION: The implantation of a stimulator over the surface of the cochlear nuclei can provide a partial auditive capability to patients deaf due to a bilateral lesion of the 8th nerve. Intraoperative monitoring of short latency electrically-evoked potentials is useful to asses the correct positioning of the implant, specially when there are anatomical distortions. PATIENTS AND METHODS: Evoked potentials from two patients with type II neurofibromatosis were recorded during implantation surgery, using a blanker system to eliminate the stimulus artifact. RESULTS: In both cases, two-peak vertex-positive responses were obtained, with latencies between 0.4-0.5 and 1.2-1.4, respectively. This responses are similar to the most frequent response described. DISCUSSION: Intraoperative monitoring of electrically-evoked auditory brainstem responses is a useful technique to confirm the correct positioning of the cochlear stimulator. The study of the morphology of these responses can help to understand the mechanisms involved in the generation by the brainstem of the auditive evoked potentials. More experience on this subject is needed to establish a correlation between intraoperative results and postoperative stimulator function.

[Neural tube dysfunction and cutaneous lesions]. / Defectos del tubo neural y lesiones cutáneas.

The aim of our article is to underline the cutaneous lesions accompanying spinal disraphysm. We would like to stress the responsibility of physicians, particularly dermatologists, pediatricians, orthopedic surgeons, urologists, neurologists and neurosurgeons to recognize as early as possible these cutaneous stigmata. In this way patients will be studied and treated as soon as possible. No cutaneous lesion in the posterior middle line of the back or close to it should be removed until any possibly associated malformation has been thoroughly studied. Otherwise the diagnosis of a subyacent spinal disraphysm might be unduly delayed and thus allow the appearance of irreversible neurological deficits. Cutaneous lesions associated with spinal disraphysm are: areas of atrophic skin, aplasia cutis congenita, congenital skin scars, dermal pits, dermal sinuses, dyschromic lesions, hyperpigmented lesions, abnormal pilifications, vascular lesions, subcutaneous lipomas, polipoid lesions simulating tails, neurofibromas, melanocitic nevus and some lesions of tumoral origin. Of there the most common cutaneous lesion associated with spinal disraphysm is the lipoma, followed by the dermal sinuses, the anomalus pilifications and the angiomas.

Use of frozen cranial vault bone allografts in the repair of extensive cranial bone defects.

In cranioplasty complexity is proportional to the size of the detect, particularly if greater than 50 cm2. If the patient's own bone flap is not available, allogenic frozen bone graft can be used instead. Between June 1990 and June 1995 twenty cranioplasties with allogenic frozen bone grafts were performed. Age of patients ranged between 23 and 63 years (average 38.4 years). Male/female ratio was 2:1.7. Size of craniectomy ranged between 65 and 150 cm2 (average 83.3 cm2). Follow-up ranged between 10 and 58 months (average 41 months). Donors were tested to rule out transmissible diseases, infections, sepsis and/or cancer. Bone grafts were removed under aseptic conditions, microbiological cultures were taken, wrapped in a gauze soaked with Gentamicin sulphate and Bacitracin, sealed in three sterilised vinyl plastic bags, and stored in a deep freezer for a minimum of 30 days (range 36-93 days, average 67 days), at a temperature of -80 degrees C. Grafts were placed in the defect after a step was carved on its borders to facilitate the contact between host and graft. Vancomycin 1 g. IV/12 hours and Ceftriaxone 1 g. IV/12 hours were administered for five days. Grafts were covered by means of scalp flaps. Only one required a musculocutaneous free flap. None was exposed, extruded or had to be removed. Plain skull X-ray studies showed progressive remodelling of the grafts. Partial resorption was observed in two (2/20, 10%) and loss of thickness in another 3/20 (15%), but with no changes in the contour. Biopsies were taken in 3/20 (15%) cases at a second surgical procedure. Areas of osteoclastic resorptive activity mixed with others of osteoblastic bone apposition, showed replacement with new bone. We conclude that cranial vault frozen allografts are a good alternative to autologous bone when the latter is absent or not present in sufficient amount.

Cranioplasty with autogenous autoclaved calvarial bone flap in the cases of tumoural invasion.

When a bone flap is raised in the course of a craniotomy, the ideal is to replace it at the end of the procedure. When it is invaded by tumoural cells, it cannot be replaced due to the risk of tumoural recurrence. In these cases we have autoclaved the bone flap to be able to replace it with no fear of tumoural recurrence. Between October 1989 and October 1995 sixty-two patients required autoclaving of the bone flap in the course of a craniotomy due to tumoural invasion (thirty-five meningiomas, sixteen bone tumours, five metastases, and eight scalp tumours). The infiltrated bone flaps were removed, cleaned, autoclaved for 20 minutes at 134 degrees C and 1 kg/cm2 and re-implanted. Patients were followed-up for 10 to 58 months (average 41 months). At every follow-up visit skull x-ray studies, clinical examination, and photographs were done. When needed a CT scan was performed to assess the thickness of the bone flap. On follow-up roentgenograms partial resorption was observed in twelve cases (19.3%). CT scan studies showed loss of thickness in another thirty-five cases (56.4%). Meanwhile the external aspect remained unchanged. In six cases (3.2%) biopsies of the bone flaps were taken at a second surgical procedure. They showed newly formed bone partly re-populated by osteocytes but retaining areas of sequestered bone. We conclude that autoclaved bone, if replaced with direct contact with living bone, it is gradually repopulated with osteocytes. Cranial vault autoclaved autologous bone flap is a good alternative when the original bone flap is invaded but not destroyed by tumoural cells.

Surgical treatment of anterior skull base tumours.

Skull base tumours represent a special challenge to surgeons due to the complex anatomy of the area. While small tumours are easy to remove, large lesions can pose complex situations. The most difficult aspects are not only the approach and removal, but specially the repair of the defects created by the resection of the tumour. We present here our experience with the surgical removal of tumours on the anterior skull base. To achieve a good approach, we resort to a bifrontal craniotomy including the cilliar arches. To obtain a skull base bone flap that can be used for repair at the end of the procedure, we remove the roof of the nose and a part of the medial wall and roof of both orbits. While the tumour is removed, the skull base bone flap is autoclaved to kill all tumoural cells. At the end of the procedure this bone flap is replaced, wrapped with a flap of pericranium. Provided no orbit needs to be emptied, no other flap is needed to reconstruct the area. One advantage is that the surgical cavity is not occluded with tissues, thus facilitating early identification of any recurrence. The area can be explored with the aid of an endoscope introduced into the nasal cavities through the nostrils, and in case of doubt, biopsies taken from all suspicious area. Our technique facilitates the repair of the surgical defect, and while not compromising the healing process it has a very low incidence of CSF leaks and infections.

Surgical treatment of insular gliomas.

Surgical treatment of glial tumours arising in the insula is specially challenging due to the proximity of the internal capsule. Although small insular gliomas have been removed safely by a transylvian approach, in large dominant insular tumours only biopsy has been recommended to avoid postoperative deficits. Unfortunately that is a suboptimal form of treatment as low grade supratentorial gliomas should be removed radically to prevent tumour progression, malignization and to increase the recurrence-free-interval. Addition of radiotherapy to partial removal is associated with a much higher incidence of recurrences and early malignizations compared to radical removal and no radiotherapy. Between 1st October 1989 and 1st September 1996 we treated twenty-three patients harbouring insular gliomas. To increase the radicality of the resection the surgical procedure was performed under local anaesthesia whenever possible, as general anaesthesia usually leads to more conservative resections. In 20/23 (86.9%) patients complete resection was accomplished, and subtotal in three (13.1%). The removed tumours were: two oligodendrogliomas, five grade I astrocytomas, nine grade II, four grade III and three grade IV. Postoperative neurological deficits occurred in five patients. Four suffered a hemiparesis (that recovered in an average of 6 months) and one a motor dysphasia which took a week to recover. Two of the seventeen patients operated on for low grade insular gliomas underwent malignant change. We conclude that complete surgical removal of insular gliomas should be considered and at least attempted in all cases.

Chiari type I malformation, glossopharyngeal neuralgia and central sleep apnoea in a child.

We describe the case of an 8-year-old child who presented with sleep breathing disorders associated with glossopharyngeal neuralgia. Polysomnographic studies showed central sleep apnoea lasting 10 to 18 seconds in an average frequency of 63 times for every hour of sleep. Magnetic resonance imaging (MRI) studies showed a caudal displacement of the cerebellar tonsils down to C3 level, associated with a syringomyelic cavity in the upper cervical cord and an extramedullary cystic collection at C2. Surgical decompression of the cranio-cervical junction completely relieved the apnoea and the glossopharyngeal neuralgia immediately following the procedure. MRI study performed one month later showed the complete disappearance of the syringomyelic cavity. Two years later this child remains asymptomatic. In childhood the association of Chiari type I malformation with sleep apnoea and glossopharyngeal neuralgia has not been previously reported. The successful outcome after surgery suggests a compressive mechanism on the brainstem and on the IX cranial nerve to explain these two clinical features in our patient.

High-dose BCNU and autologous progenitor cell transplantation given with intra-arterial cisplatinum and simultaneous radiotherapy in the treatment of high-grade gliomas: benefit for selected patients.

A phase II study of postoperative high-dose carmustine (HDBCNU), intracarotid cisplatin (CDDP), and radical radiotherapy in patients with high-grade glioma was performed. Patients underwent 4-6 consecutive days of blood hematopoietic progenitor cell (HPC) apheresis without prior mobilization. Chemotherapy included intracarotid CDDP, 60 mg/m2, and BCNU, 900 mg/m2. HPC were infused 48 h after HDBCNU. Whole brain irradiation, up to 50 Gy, was started on the 8th day after HPC infusion. With a median follow-up time of 44 months, median overall survival was 15.5 months. Eight patients (23.5%) are alive free of disease 2-6 years after treatment (seven out of 25 patients with glioblastoma multiforme and one out of nine patients with anaplastic astrocytoma). Survival was influenced by young age, good performance and complete surgical resection. Two patients (5.8%) died of therapy-related complications. Acute hematological toxicity of HDBCNU was moderate, with a full recovery on day 26. No acute pulmonary or hepatic toxicity was found. Late severe neurological toxicity was observed in one third of patients surviving beyond 2 years. We conclude that HDBCNU, 900 mg/m2, intracarotid CDDP and radical radiotherapy appear to benefit some patients with high-grade gliomas, and phase III studies should preferentially select young patients with resectable tumors.

Occult spinal dysraphism: a neurosurgical problem with a dermatologic hallmark.

Lumbosacral congenital cutaneous lesions have been recognized for a long time by neurologists and neurosurgeons as markers of occult spinal defects, but only a few cases have been published and discussed in the dermatologic literature. Based on a case report, we emphasize the importance of early diagnosis of these lesions, the use of new diagnostic techniques, and the correct management.

Response of experimental epileptic focus to focal ionizing radiation.

An experimental model of cobalt-induced epilepsy was performed on 15 cats. 3 months later, they were irradiated by means of a gamma source with a total target dose of 10 Gy. One month after irradiation all EEG recordings returned to normal, while a control group maintained the epileptiform traces. Histological study of the irradiated foci showed neuronal reafferentation. The action mechanism of ionizing radiation over epileptogenic foci in relation to this reafferentation and neuronal plasticity mechanisms is discussed.