Dorsal midbrain encephalitis caused by Propionibacterium acnes. Report of two cases

A syndrome of dorsal midbrain dysfunction in association with a central nervous system anaerobic diphtheroid infection is described. Two cases of infection with Propionibacterium acnes manifested as shunt malfunctions with a clinical dorsal midbrain syndrome. Magnetic resonance images showed increased signal in the midbrain tectum which has decreased slowly over time. The evidence suggesting that this syndrome represents bacterial midbrain encephalitis is discussed.

Acute cervical myelopathy from hereditary multiple exostoses: case report

A case of hereditary multiple exostoses with acute cervical myelopathy, tetraplegia, and apnea is reported. Neurological complications as a result of osteochondromas in hereditary multiple exostoses are rare. The majority of osteochondromas in the cervical spine arise from the neural arch. Magnetic resonance imaging and computed tomography are invaluable in localizing the origin of the lesion and its relationship to the spinal cord. Decompressive laminectomy usually results in excellent functional recovery. Where significant dorsal spinal cord compression exists without neurological deficit, prophylactic decompression can be recommended.

Efficacy of antibiotic prophylaxis in clean neurosurgical operations

Four controlled trials and one case control study have presented data supporting the efficacy of perioperative administration of antibiotics in reducing the rate of infection following clean neurosurgical procedures. Their results are, for the most part, consistent with uncontrolled studies reported since 1980. Taken together, these studies clearly and consistently demonstrate the value of perioperative antibiotic prophylaxis in clean neurosurgical operations.

Function of parietal and frontal shunts in childhood hydrocephalus

This study was performed to determine if cerebrospinal fluid (CSF) shunts inserted via the frontal and parietal regions function for similar lengths of time. The medical records of 114 children with CSF shunts were reviewed. In 83 of these cases computerized tomography scans were also available. Ninety percent of the operations were to insert the child's first shunt. The site of insertion, cause of hydrocephalus, patient's age, surgeon, duration of function (time from insertion to malfunction or to latest follow-up evaluation), presence of infection, catheter location within the ventricle, and duration of function of the subsequent shunt were recorded. Data were analyzed by the chi-square, logistic regression, and life-table methods. Shunts had been inserted via the frontal route in 62 children and via the parietal route in 52. The children's ages, causes of hydrocephalus, and infection rates were similar in both groups. Duration of shunt function was predicted by the site of shunt insertion and the catheter position within the ventricles: shunts inserted via the frontal region functioned significantly longer than parietally inserted shunts, both as the initial shunt (Wilcoxon, p = 0.0008) and after a malfunction, and catheters positioned within the ipsilateral frontal horn functioned significantly longer than those in other ventricular locations (Wilcoxon, p = 0.03).

Optic nerve decompression for osteopetrosis in early childhood

Visual failure in osteopetrosis may result from retinal degeneration or compression of the optic nerve in the narrowed optic canals. We report the evaluation and treatment of five children with osteopetrosis whose optic nerve dysfunction seems to have been related to the latter etiology. Evaluation of visual function was carried out by means of behavioral observation and flash visual evoked responses. Of six nerves evaluated both pre- and postoperatively, the visual evoked responses seemed to improve in four. Three nerves were serially evaluated without an operation, and one showed changes consistent with maturation. One nerve was evaluated with serial postoperative evoked potentials and showed no change. We conclude that surgical decompression of the optic nerve in patients with documented optic nerve dysfunction and osteopetrosis allows improvement in visual function and is, therefore, an important consideration in the evaluation and management of patients with this disease.

Congenital supratentorial and infratentorial peripheral neurogenic tumor: a clinical, ultrastructural, and immunohistochemical study

Congenital neoplasms of the central nervous system are extremely rare, although they have been well documented since the earliest reports from the mid-19th century. Medulloblastoma, other primitive neuroectodermal tumors, and various types of gliomas have comprised the majority of cases. This report describes a highly unusual infratentorial and supratentorial tumor presenting as a scalp mass in a neonate who experienced in utero distress. The supratentorial mass extended through a defect in the skull to the parietooccipital lobe, and the infratentorial aspect involved the 9th and 10th cranial nerves in the region of the cerebellopontine angle. A complex spindle cell neoplasm incorporating peripheral nerve sheath and vascular characteristics was further characterized by electron microscopy and immunohistochemistry. Based upon these studies, the tumor was interpreted as a congenital schwannoma with divergent vascular differentiation. The child has been tumor-free for approximately 2 years after the initial operative procedure.

Risk factors for postoperative neurosurgical wound infection. A case-control study

A case-control analysis was performed to evaluate the association of 15 potential risk factors with postoperative infection in neurosurgical patients. All infections that developed postoperatively on the neurosurgical service at the University of Minnesota from January, 1970, to March, 1984, were identified. Among the 9202 operations performed during that time, 101 infections occurred for a rate of 1.1%. Three risk factors showed significant association with postoperative infection: cerebrospinal fluid (CSF) leak, concurrent noncentral nervous system (CNS) infection, and perioperative antibiotic therapy. The presence of a CSF leak and a concurrent non-CNS infection increased the estimated relative risk of infection to 13:1 and 6:1, respectively. The use of perioperative antibiotics was associated with a decrease in the risk of infection to approximately 20% of the control level. Three other risk factors (paranasal sinus entry, placement of a foreign body, and use of a postoperative drain) appeared to be associated with increased risk of infection, although statistical significance was not demonstrated. None of the remaining nine risk factors studied showed any suggestion of increased risk of infection.

Anticonvulsant prophylaxis in neurological surgery

Seizures complicate many neurosurgical diseases and, in many situations, their prevention is desirable. In an attempt to arrive at a rational approach to the purely prophylactic administration of anticonvulsants, existing data pertaining to four topics were examined: the danger posed by a single seizure, the incidence of seizures in a given disease state, the ability of anticonvulsant medication to prevent seizures, and the risks and benefits associated with pharmacological intervention. In general, where the risk of seizure exceeds 10 to 15% or where a single seizure may have disastrous consequences, anticonvulsant prophylaxis is recommended.

The chymopapain clinical trials

The three published randomized clinical trials of chymopapain injection vs. placebo injection for the treatment of herniated lumbar discs are reviewed. Despite some differences, the similarities in selection criteria, technique, and outcome assessment are great enough to justify pooling the results to obtain an overall assessment of chymopapain efficacy. These pooled results suggest that the odds of successful outcome (at least some improvement in symptoms after injection) are 2.6 times as great with chymopapain injection as those after placebo injection. This corresponds to a 50% greater probability of success with chymopapain than with placebo or a 23% increase in the number of patients successfully treated with chemonucleolysis over those successfully treated with placebo. The fact that data from 234 patients evaluated in randomized clinical trials could resolve a controversy over therapeutic efficacy that the uncontrolled evaluation of over 20,000 patients could not answer suggests that the current controversy over the relative efficacy of chymopapain and discectomy should be studied in the same way. The difficulties of such a study are discussed.

Tuberous sclerosis: a review for the neurosurgeon

The clinical, radiological, and pathological characteristics of tuberous sclerosis are reviewed. Neurosurgical intervention in the syndrome is discussed in light of two recently treated cases and a literature review.

Randomized clinical trials in neurosurgery

Fifty-one randomized trials of neurosurgical topics have been identified. These have been analyzed for content, quality of reporting, and quality of statistical design and analysis. In general, there were major omissions in the reporting of critical portions of the studies, the statistical analysis was highly variable in quality, and the statistical power was low. Few, if any, major neurosurgical questions have been answered by clinical trials. This may reflect the generally low quality of these trials. To improve the quality of such trials, neurosurgeons must seek biostatistical advice in planning and conducting trials and must cooperate in multi-institutional trials to increase statistical power.

Topical antibiotic prophylaxis in neurosurgery

Topical antibiotics have been used prophylactically in clean operations by many neurosurgeons. Many others have not used them, however. Review of the experimental literature shows that topical antibiotics will reduce the rate of wound infection in experimentally contaminated wounds. Experience in other surgical disciplines suggests that the infection rate of operations with an intrinsically high risk of infection (greater than 15%) can be reduced substantially by the use of topical antibiotics. There is no sound scientific evidence documenting the benefit of prophylactic topical antibiotics in operations with a risk of infection below 5%. Reports of the use of topical antibiotics in neurosurgery are either uncontrolled or are so fragmentary that no useful-conclusions can be drawn from them. Surgical wounds with a high risk of infection should be treated with intraoperative topical antibiotics. The routine use of topical antibiotics in clean neurosurgical procedures requires further study.

Antibiotic prophylaxis of postoperative neurosurgical wound infection

In an effort to reduce the incidence of postoperative wound infection, the recently proposed regimen of intravenous vancomycin and tobramycin and streptomycin irrigating solution was used in 878 neurosurgical operations. There were eight infections, for an infection rate of 0.9%. This infection rate was compared to the rate in the previously reported series using a sequential statistical analysis. The infection rate was found to be significantly greater than that previously reported. Controlled clinical trials will be required before the efficacy of antibiotic prophylaxis in clean neurosurgical procedures can be considered proven.

Prophylactic methicillin for shunt operations: effects on incidence of shunt malfunction and infection

In a double-blind study, 74 children were randomly treated with prophylactic methicillin at the time of ventriculo-peritoneal shunting. There were 7 infections in the placebo group and 2 in the methicillin-treated group. There was no statistically significant difference in infection or overall malfunction rate between the two groups. The risk of shunt malfunction in the 2nd to 6th month after surgery was significantly greater in the placebo group (7 of 26 patients) than in the methicillin-treated group (1 of 26 patients). Delayed shunt malfunction may be prevented by a short course of perioperative antibiotics.

Six statistical suggestions for surgeons

Statistical analysis has become very important in medical research. The large number and variety of statistical techniques required to appropriately handle different types of medical research make it impossible for most physicians to acquire enough statistical expertise to analyze critically the details of many reports. However, a basic understanding of certain fundamental principles of statistical analysis is vital if statistical errors and misapplications are to be identified and prevented. The basic principles underlying six common statistical errors are discussed and a guide to pertinent literature is provided so that the practicing physician without special statistical knowledge can be in a better position to understand and interpret statistical analysis in the medical literature.

Systemic antibiotic prophylaxis in neurological surgery

The clinical and experimental bases for antibiotic prophylaxis in surgery are reviewed briefly. The evidence regarding antibiotic prophylaxis in five specific neurosurgical situations (clean surgical procedures, cerebrospinal fluid shunts, external venticulostomies, basilar skull fractures, and compound skull fractures) is examined. There are no unequivocal indications for antibiotic prophylaxis in neurological surgery. Large scale randomized clinical trials will be required to settle the controversy in some of these areas.

Microvascular relations of the trigeminal nerve. An anatomical study with clinical correlation

The vascular relationships of the trigeminal nerve root entry zone were examined bilaterally in 20 cadavers of individuals known to be free of facial pain. Fourteen of 40 nerves made contact with an artery, but only four of these showed evidence of compression or distortion of the nerve. In addition, the vascular relationships of 40 trigeminal nerves exposed surgically for treatment of trigeminal neuralgia were studied, and 31 nerves showed compression by adjacent arteries. Venous compression was seen in four of the cadaver nerves and in eight nerves from patients with trigeminal neuralgia. These data support the hypothesis that arterial compression of the trigeminal nerve is associated with trigeminal neuralgia.

Randomized clinical trials in the evaluation of surgical innovation

Randomized clinical trials are widely accepted as the standard for evaluation of therapeutic innovation in many fields of medicine. The three basic components of such trials (concurrent comparison, random allocation, and objective observation) are designed to control four forms of bias (chronology bias, susceptibility bias, compliance bias, and observation bias) that may interfere with the interpretation of the results of a study. Only 2% of the articles evaluating therapeutic maneuvers published in the Journal of Neurosurgery have attempted to use concurrent controls. Only one of 863 such articles met the criteria for a randomized clinical trial. Reasons for underutilization of such trials in neurosurgery are discussed and suggestions for their wider use are offered.

Calvarial hemangioendothelioma with intracranial hemorrhage: case report

A case of a hemangioendothelioma of the occipital bone that presented clinically as an acute epidural hematoma is reported. The literature regarding this rare bone tumor is reviewed. The treatment of choice seems to be wide surgical excision, but life-threatening hemorrhage may occur due to extreme tumor vascularity. The role of radiotherapy remains uncertain.

Arterial cross compression of the trigeminal nerve at the pons in trigeminal neuralgia. Case report with autopsy findings

The autopsy findings in a patient with trigeminal neuralgia who died from unrelated causes are presented. Arterial cross compression of the appropriate trigeminal nerve at the pons was demonstrated. The relationship of arterial cross compression to trigeminal neuralgia is briefly discussed.

Supratentorial intracerebral hemorrhage following posterior fossa surgery

Five cases of supratentorial intracerebral hemorrhage following posterior fossa surgery are reported. Possible etiologies are discussed, but in only one case can a definite etiology (hypertension) be found. The differential diagnosis of declining level of consciousness after posterior fossa surgery must include supratentorial intracerebral hemorrhage, and computerized tomography seems to be the diagnostic method of choice.