Marcus C. Korinth

LONG-TERM RESULTS OF MICROSURGICAL TREATMENT OF LUMBAR SPINAL STENOSIS BY UNILATERAL LAMINOTOMY FOR BILATERAL DECOMPRESSION

OBJECTIVELaminectomy and bilateral laminotomy are the standard procedures for decompression of lumbar spinal stenosis (LSS). With the aim of less invasiveness and better preservation of spinal stability, the technique of unilateral laminotomy for bilateral decompression (ULBD) was developed. However, limited follow-up data exist to determine the efficiency and outcome of ULBD. Therefore, the authors present their 10-year experience with ULBD and postoperative long-term results. METHODSOne hundred thirty-three consecutive patients (73 men and 60 women; mean age, 63 yr) meeting clinical and radiographic criteria for LSS who underwent first-time ULBD between 1994 and 1999 entered the study. The study parameters were set to ensure a follow-up period of at least 4 years. All patients were available for short-term follow-up re-evaluation within 3 months, and 102 (77%) of the 133 patients were available for long-term examination after a mean duration of 5.6 years. The scale of Finneson and Cooper was used for evaluation of the clinical results. RESULTSOne hundred thirty patients (97.7%) improved immediately after surgery. Ninety-four (92.2%) of the 102 patients available for long-term follow-up examination remained improved, and 85.3% had an excellent-to-fair operative result. The incidence of complications was 9.8%. Resurgery for complication was necessary in three patients, for restenosis in seven patients, and for spinal instability in two patients, accounting for a reoperation rate of 11.8%. CONCLUSIONULBD allows achievement of good and long-lasting operative results in patients with LSS. Postoperative deterioration, recurrences, and spinal instability are infrequent. For the authors, ULBD is the preferred technique to treat symptomatic LSS.

Pathogenesis, diagnosis and management of pneumorrhachis

Pneumorrhachis (PR), the presence of intraspinal air, is an exceptional but eminent radiographic finding, accompanied by different aetiologies and possible pathways of air entry into the spinal canal. By reviewing the literature and analysing a personal case of traumatic cervical PR after head injury, we present current data regarding the pathoanatomy, clinical and radiological presentation, diagnosis and differential diagnosis and treatment modalities of patients with PR and associated pathologies to highlight this uncommon phenomenon and outline aetiology-based guidelines for the practical management of PR. Air within the spinal canal can be divided into primary and secondary PR, descriptively classified into extra- or intradural PR and aetiologically subsumed into iatrogenic, traumatic and nontraumatic PR. Intraspinal air is usually found isolated not only in the cervical, thoracic and, less frequently, the lumbosacral regions but can also be located in the entire spinal canal. PR is almost exceptional associated with further air distributions in the body. The pathogenesis and aetiologies of PR are multifold and can be a diagnostic challenge. The diagnostic procedure should include spinal CT, the imaging tool of choice. PR has to be differentiated from free intraspinal gas collections and the coexistence of air and gas within the spinal canal has to be considered differential diagnostically. PR usually represents an asymptomatic epiphenomenon but can also be symptomatic by itself as well as by its underlying pathology. The latter, although often severe, might be concealed and has to be examined carefully to enable adequate patient treatment. The management of PR has to be individualized and frequently requires a multidisciplinary regime.

Metabolic and electrophysiological validation of functional MRI

OBJECTIVES Although functional MRI is widely used for preoperative planning and intraoperative neuronavigation, its accuracy to depict the site of neuronal activity is not exactly known. Experience with methods that may validate fMRI data and the results obtained when coregistering fMRI with different preoperative and intraoperative mapping modalities including metabolically based 18F-fluorodeoxyglucose PET, electrophysiologcally based transcranial magnetic stimulation (TMS), and direct electrical cortical stimulation (DECS) are described. METHODS Fifty patients were included. PET was performed in 30, TMS in 10, and DECS in 41 patients. After coregistration using a frameless stereotactic system, results were grouped into overlapping (<1 cm distance), neighbouring (<2 cm), or contradictory (>2 cm). RESULTS Comparing fMRI with PET, 18 overlapping, seven neighbouring, and one contradictory result were obtained. In four patients no comparison was possible (because of motion artefacts, low signal to noise ratio, and unusual high tumour metabolism in PET). The comparison of TMS and fMRI showed seven overlapping and three neighbouring results. In three patients no DECS results could be obtained. Of the remaining 38 patients, fMRI hand motor tasks were compared with DECS results of the upper limb muscles in 36 patients, and fMRI foot motor tasks were compared with DECS results of the lower limb on 13 occasions. Of those 49 studies, overlapping results were obtained in 31 patients, and neighbouring in 14. On four occasions fMRI did not show functional information (because of motion artefacts and low signal to noise). CONCLUSIONS All validation techniques have intrinsic limitations that restrict their spatial resolution. However, of 50 investigated patients, there was only one in whom results contradictory to fMRI were obtained. Although it is not thought that fMRI can replace the intraoperatively updated functional information (DECS), it is concluded that fMRI is an important adjunct in the preoperative assessment of patients with tumours in the vicinity of the central region.

Posterior foraminotomy or anterior discectomy with polymethyl methacrylate interbody stabilization for cervical soft disc disease : Results in 292 patients with monoradiculopathy

Study Design. Retrospective study of patients who underwent either ventral microdiscectomy and polymethyl methacrylate (PMMA) interbody stabilization or posterior foraminotomy for the treatment of cervical monoradiculopathy caused by soft disc disease. Objectives. To evaluate the long-term outcome after 2 different surgical procedures in the treatment of cervical radiculopathy, compare them with each other and with previous data from other surgical techniques, and outline the indications, advantages, and disadvantages of each procedure. Summary of Background Data. Cervical disc disease can lead to morphologic different disc lesions, which again may differ in clinical presentation, operative treatment, and outcome. This study provides a clinical long-term follow-up of ventral and dorsal approaches. Methods. Follow-up evaluation (mean 72.1 ± 25.9 months) after surgery of monoradicular symptoms was performed in 292 patients. Patients with hard disc disease, myelopathy, neoplasms, or traumatic or recurrent cervical disc disease were excluded. A total of 124 patients (42.5%) underwent ventral microdiscectomy and PMMA stabilization (group A), and in 168 patients (57.5%), a posterior foraminotomy was performed (group B). The outcome was determined according to Odom criteria based on a questionnaire or a telephone interview and was related to the following variables: morphologic findings, neurologic findings, duration of symptoms, operation technique applied, age, sex, and cervical level involved. Results. The success rate (Odom I + II) without consideration of morphologic findings was higher after anterior microdiscectomy with PMMA stabilization (93.6%) than after posterior foraminotomy (85.1%) (P < 0.05). The success rate was higher in cases with pure soft discs in both groups (A: 96.6%; B: 85.8%) than in cases with a mixture of soft and hard discs (A: 90.6%; B: 80%), without gaining statistical significance. Complications related to surgery occurred in 6.5% (group A) and 1.8% (group B) of patients (P < 0.05). Conclusion. The findings show that apparently a higher success rate results after anterior microdiscectomy with PMMA interbody stabilization for treatment of degenerative cervical monoradiculopathy than after posterior foraminotomy. Considering the type of morphology of the pathology that causes the radiculopathy, pure soft discs have a better outcome than mixtures of soft and hard discs, independent of the chosen approach. Although statistically significant differences in clinical data were found in both groups, both approaches seem to have equivalent value in individual indications.

Proton magnetic resonance spectroscopy of neurocytoma outside the ventricular region – case report and review of the literature

Abstract. Central neurocytoma is classically considered as an intraventricular benign tumour, largely based on data from small retrospective series and single case reports. We report on a 16-year-old girl who suffered from a large parietooccipital tumour that was diagnosed histologically as central neurocytoma. The features of CT, MRI and proton MR spectroscopy studies are discussed. This is the first report on spectroscopic findings in a case of extraventricular neurocytoma. As well as elevated choline (Cho), the tumour spectrum showed strongly decreased N-acetylaspartate (NAA). NAA is assumed to be produced in mature neurons, and we therefore expected to find high amounts of NAA in this well-differentiated tumour, which was histologically composed of mature neuronal tissue. This observation leads to the conclusion that even the highly differentiated cells of neurocytomas are too immature to produce NAA.

Low-dose aspirin before intracranial surgery--results of a survey among neurosurgeons in Germany.

SummaryBackground. Increasing numbers of patients presenting for intracranial surgery are receiving concurrent medication with low-dose aspirin, leading to dysfunctional circulating platelets, which might increase the peri-operative risk of bleeding.Objective. To survey the opinions and working practices of neurosurgical facilities in Germany regarding patients who present with low-dose aspirin medication before elective intracranial surgery.Methods. Questionnaires were sent to 210 neurosurgical facilities asking five main questions: (1) the adherence of any policy of stopping aspirin pre-operatively, (2) the personal risk assessment for patients with brain surgery under low-dose aspirin medication, (3) the preferred method of treatment for excessive bleeding in this context, (4) personal knowledge of haemorrhagic complications in this group of patients, and (5) the characteristics of the neurosurgical units concerned.Results. There were 138 (65.7%) valid responses. Of the respondents, 111 (80.4%) had a departmental policy for the discontinuation of pre-operative aspirin treatment. The mean time for discontinuation of aspirin pre-operatively was 7.3 days (range: 0–21 days). 107 respondents (77.5%) considered that patients taking low-dose aspirin were at increased risk for excessive peri-operative haemorrhage, and 80 (58%) reported having personal experience of such problems. Ninety-seven respondents (70.3%) would use special medical therapy, preferably desmopressin, if haemorrhagic complications developed intra-operatively. The mean amount of intracranial operations per year in each neurosurgical facility was 494 (range: 50–1700).Conclusions. The majority of neurosurgical facilities in Germany have distinct departmental policies concerning the discontinuation of low-dose aspirin pre-operatively, with an average of 7.3 days. Three-quarter of the respondents felt that aspirin was a risk factor for haemorrhagic complications associated with intracranial procedures, and more than half of the interviewees reported having personal experience of such problems. Various medicamentous methods of counteracting aspirin-induced platelet dysfunction and excessive bleeding in this context are discussed and evaluated.

Pneumorrhachis of the entire spinal canal

Pneumorrhachis (PR)—the curious phenomenon of intraspinal air—is an exceptional radiographic finding. In this report the first case of PR of the entire spine is presented. A 19 year old man with a history of diabetes mellitus and bronchial asthma was admitted because of cough, fever, nausea, and vomiting for 3 days. Physical examination and laboratory studies showed cervical subcutaneous emphysema, infection signs, and ketoacidotic decompensated …

Endoscopic transtentorial ventriculocystostomy and cystoventriculoperitoneal shunt in a neonate with Dandy-Walker malformation and associated aqueductal obstruction.

Objective: Shunting of the lateral ventricle and the posterior fossa cyst is the advocated surgical therapy for children with Dandy-Walker malformation (DWM) and associated aqueductal obstruction. The high rate of complications of combined shunting stimulated the authors to search for an alternative surgical solution. Clinical Presentation/Intervention: After transtentorial endoscopic ventriculocystostomy, a cystoventricular catheter, connected to a peritoneal shunt, was placed in a neonate with DWM and associated aqueductal obstruction. Immediately prior to ventriculocystostomy, the presence of a blocked third ventricular outflow was reconfirmed by contrast medium injection. Neuronavigation was required to define the surgical path from the lateral ventricle through the tentorium and the overlying small rim of brain parenchyma into the posterior fossa cyst. The postoperative clinical course was uneventful with radiologically proven reduction of the size of the ventricular system and the cyst. Conclusion: Cystoventriculoperitoneal shunt placement after transtentorial endoscopic ventriculostomy is a surgical alternative in very young children with DWM and associated aqueductal obstruction.

Primary intraventricular schwannomas

Schwann cell tumors arising within the neuraxis and in an intraventricular location are an exceedingly rare tumor entity of the brain. The authors present the first case of a cellular intraventricular schwannoma occurring in the fourth ventricle. The pertinent literature is reviewed. A 71-year-old female was admitted to the hospital with an incidental finding of a ventricular tumor. Computed tomography scanning and magnetic resonance imaging revealed a solitary contrast enhancing exophytic mass lesion within the fourth ventricle. Microsurgical excision via a midline suboccipital craniotomy and tonsillo-nodular approach led to complete tumor removal. Subsequent histopathological examination confirmed the diagnosis of an unsuspected primary intraventricular cellular schwannoma. A unique case of an initially unexpected benign schwannoma arising from the fourth ventricle that could be successfully treated by microsurgery and finally confirmed by histopathological analysis with excellent patient outcome is presented. Although highly uncommon, Schwann cell tumors of both benign and malignant nature may present as ventricular lesions and should be included as a differential diagnosis in patients with either solely intraventricular masses or intra- and extraaxial tumors with extension to the ventricles.

Pterional orbita decompression in orbital hemorrhage and trauma.

BACKGROUND This article presents a series of patients with traumatic retrobulbar hematoma and orbital trauma, treated with extended pterional orbital decompression. METHODS Fifteen patients, showing symptomatic retrobulbar hematoma or symptoms of orbital injury after various trauma mechanisms, were treated with deep lateral orbital decompression and removal of orbital blood/bone fragments via this approach. Preoperative and postoperative course, neuroradiologic findings, additional brain or facial injuries, and outcome of eye function are analyzed in detail. RESULTS Mean delay between trauma and decompression was 70 hours (3 days), with a range from 2 hours to 15 days. Proptosis decreased in all patients and visual acuity improved or remained normal in nine patients and stayed defective in four. Impaired extraocular movements and pupillary changes recovered in 10 patients. Apart from one case of permanent deficit of the frontal branch of the facial nerve, no severe complications were seen. CONCLUSION The presented pterional orbital decompression represents an effective alternative approach for patients with sight-threatening retrobulbar hematoma or orbital trauma, especially in cases that require direct access to damaged structures and maximal decompression of the orbit. Immediate detection and treatment of orbital hematomas is mandatory for acceptable outcome of eye function.