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S. Scott Lollis and David W. Roberts

Object

Robotic applications hold great promise for improving clinical outcomes and reducing complications of surgery. To date, however, there have been few widespread applications of robotic technology in neurosurgery. The authors hypothesized that image-guided robotic placement of a ventriculostomy catheter is safe, highly accurate, and highly reproducible.

Methods

Sixteen patients requiring catheter ventriculostomy for ventriculoperitoneal (VP) shunt or reservoir placement were included in this retrospective study. All patients underwent image-guided robotic placement of a ventricular catheter, using a preoperatively defined trajectory.

Results

All catheters were placed successfully in a single pass. There were no catheter-related hemorrhages and no injuries to adjacent neural structures. The mean distance of the catheter tip from the target was 1.5 mm. The mean operative times were 112 minutes for VP shunt placement and 42.3 minutes for reservoir placement. The mean operative times decreased over the course of the study by 49% for VP shunts and by 19% for reservoir placement.

Conclusions

The robotic placement of a ventriculostomy catheter using a preplanned trajectory is safe, highly accurate, and highly reliable. This makes single-pass ventriculostomy possible in all patients, even in those with very small ventricles, and may permit catheter-based therapies in patients who would otherwise be deemed poor surgical candidates because of ventricle size. Robotic placement also permits careful preoperative study and optimization of the catheter trajectory, which may help minimize the risks to bridging veins and sulcal vessels.

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Wesley J. Whitson, Perry A. Ball, S. Scott Lollis, Jason D. Balkman and David F. Bauer

Object

Mycoplasma hominis is a rare cause of infection after neurosurgical procedures. The Mycoplasma genus contains the smallest bacteria discovered to date. Mycoplasma are atypical bacteria that lack a cell wall, a feature that complicates both diagnosis and treatment. The Gram stain and some types of culture media fail to identify these organisms, and typical broad-spectrum antibiotic regimens are ineffective because they act on cell wall metabolism. Mycoplasma hominis commonly colonizes the genitourinary tract in a nonvirulent manner, but it has caused postoperative, postpartum, and posttraumatic infections in various organ systems.

The authors present the case of a 17-year-old male with a postoperative intramedullary spinal cord abscess due to M. hominis and report the results of a literature review of M. hominis infections after neurosurgical procedures. Attention is given to time to diagnosis, risk factors for infection, ineffective antibiotic regimens, and final effective antibiotic regimens to provide pertinent information for the practicing neurosurgeon to diagnose and treat this rare occurrence.

Methods

A PubMed search was performed to identify reports of M. hominis infections after neurosurgical procedures.

Results

Eleven cases of postneurosurgical M. hominis infection were found. No other cases of intramedullary spinal cord abscess were found. Initial antibiotic coverage was inadequate in all cases, and diagnosis was delayed in all cases. Multiple surgical interventions were often needed. Once appropriate antibiotics were started, patients typically experienced rapid resolution of their neurological symptoms. In 27% of cases, a suspicious genitourinary source other than urinary catheterization was identified.

Conclusions

Postoperative M. hominis infections are rarely seen after neurosurgical procedures. They are typically responsive to appropriate antibiotic therapy. Mycoplasma infection may cause prolonged hospitalization and multiple returns to the operating room due to delay in diagnosis. Early clinical suspicion with appropriate antibiotic coverage could help prevent these significant complications.

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S. Scott Lollis, Pablo A. Valdes, Zhongze Li, Perry A. Ball and David W. Roberts

Object

The authors sought to determine a cause-specific mortality profile for US neurosurgeons during the period 1979–2005.

Methods

Neurosurgeons who died during the study period were identified from the Physician Master File database. Using the National Death Index, the reported cause of death was identified for 93.7% of decedents. Standardized mortality ratios were used to compare mortality risk in the study cohort to that of the US population.

Results

There was a marked reduction in mortality from virtually all causes in comparison with the control population. This finding is consistent with prior studies of mortality in physicians. The small number of deaths among female neurosurgeons precluded meaningful analysis for this group. Increased mortality risk for male neurosurgeons was seen from leukemia, nervous system disease (particularly Alzheimer disease), and aircraft accidents. Deaths from viral hepatitis and HIV infection, considered to be occupational hazards for surgeons, were less frequent than in the general population. Suicide, drug-related deaths, and alcohol-related deaths were less frequent than in the general population.

Conclusions

Neurosurgeons may be at higher risk for death from leukemia, aircraft accidents, and diseases of the nervous system, particularly Alzheimer disease; however, the mortality profile of neurosurgeons is favorable when compared with the general population.

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S. Scott Lollis, P. Jack Hoopes, Susan Kane, Keith Paulsen, John Weaver and David W. Roberts

Object

Intracisternal injection of kaolin is a well-described model of feline hydrocephalus. Its principal disadvantage is a high rate of procedure-related morbidity and mortality. The authors describe a series of modifications to a commonly used protocol, intended to ameliorate animal welfare concerns without compromising the degree of ventricular enlargement.

Methods

In 11 adult cats, hydrocephalus was induced by injection of kaolin into the cisterna magna. Kaolin doses were reduced to 10 mg, compared with historical doses of ~ 200 mg, and high-dose dexamethasone was used to reduce the severity of meningeal irritation. A control cohort of 6 additional animals received injections of isotonic saline into the cisterna magna.

Results

The mean ventricular volume increased from a baseline of 0.183 ± 0.068 ml to 1.43 ± 0.184 ml. Two animals were killed prior to completion of the study. Of the remaining animals, all were ambulatory by postinjection Day 1, and all had resumed normal oral intake by postinjection Day 3. Two animals required subcutaneous fluid supplementation. Ventriculostomy using anatomical landmarks was performed to ascertain intraventricular pressure. The mean intraventricular pressure after hydrocephalus was 15 cm H2O above the ear (range 11–20 cm H2O).

Conclusions

Reduction in kaolin dosage and the postoperative administration of high-dose corticosteroid therapy appear to reduce morbidity and mortality rates compared with historical experiences. Hydrocephalus is radiographically evident as soon as 3 days after injection, but it does not substantially interfere with feeding and basic selfcare. To the extent that animal welfare concerns may have limited the use of this model in recent years, the procedures described in the present study may offer some guidance for its future use.

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S. Scott Lollis, Dudley J. Weider, Joseph M. Phillips and David W. Roberts

Object

The goal of this study was to provide preliminary data regarding clinical and functional outcome, including postoperative morbidity, related to ventriculoperitoneal (VP) shunt insertion for refractory perilymphatic fistula.

Methods

The authors retrospectively reviewed the records of seven consecutive patients who had undergone VP shunt insertion for medically and surgically refractory perilymphatic fistula between 1996 and 2004. Patients were also contacted by telephone and asked to assess retrospectively their symptomatic improvement, changes in functional status, and changes in work status following shunt placement. Preoperative and postoperative functional statuses were assessed using a standardized instrument. In each patient, preoperative opening pressure was measured via lumbar puncture. Pressures ranged from 160 to 300 mm H2O, with a mean of 241 mm H2O.

All patients reported significant improvement in symptom severity following surgery. Two patients reported complete resolution of symptoms. Three patients were able to resume full-time work. Clinically significant improvement in functional status was noted in six of seven patients. All patients would recommend the procedure to others in a similar situation.

Conclusions

Data in this study suggest that some patients with disabling vertigo, tinnitus, and headache due to perilymphatic fistula, whose conventional medical and surgical therapies have failed to produce a cure, benefit from VP shunt insertion. The authors hypothesize that VP shunt placement blunts intracranial pressure increases, which would cause secondary elevations in perilymphatic fluid pressure. Shunt insertion reduces perilymph leakage into the middle ear and may permit closure of the fistula.

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S. Scott Lollis, Eugen B. Hug, David J. Gladstone, Sara Chaffee and Ann-Christine Duhaime

✓The authors present the case of a 20-month-old boy who underwent fractionated radiation therapy to the paranasal sinuses and anterior skull base during treatment for nasopharyngeal parameningeal rhabdomyosarcoma. Subsequent magnetic resonance imaging demonstrated progressive development of a Chiari malformation Type I (CM-I) and partial hypoplasia of the posterior fossa. Since the tonsillar herniation was discovered, the child, now 3 years old, remains asymptomatic except for mild, intermittent neck discomfort. For the time being, his family has elected for him to undergo clinical and neuroimaging follow up. The authors believe this is the first report of a progressive acquired CM-I after cranial irradiation in the pediatric population.

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Sebastian Rubino, Rifat A. Zaman, Caleb R. Sturge, Jessica G. Fried, Atman Desai, Nathan E. Simmons and S. Scott Lollis

Object

Many neurosurgeons obtain repeat head CT at the first clinic follow-up visit for nonoperative cerebral contusion and traumatic subarachnoid hemorrhage (tSAH). The authors undertook a single-center, retrospective study to determine whether outpatient CT altered clinical decision-making.

Methods

The authors evaluated 173 consecutive adult patients admitted to their institution from April 2006 to August 2012 with an admission diagnosis of cerebral contusion or tSAH and at least 1 clinic follow-up visit with CT. Patients with epidural, subdural, aneurysmal subarachnoid, or intraventricular hemorrhage, and those who underwent craniotomy, were excluded. Patient charts were reviewed for new CT findings, new patient symptoms, and changes in treatment plan. Patients were stratified by neurological symptoms into 3 groups: 1) asymptomatic; 2) mild, nonspecific symptoms; and 3) significant symptoms. Mild, nonspecific symptoms included minor headaches, vertigo, fatigue, and mild difficulties with concentration, short-term memory, or sleep; significant symptoms included moderate to severe headaches, nausea, vomiting, focal neurological complaints, impaired consciousness, or new cognitive impairment evident on routine clinical examination.

Results

One hundred seventy-three patients met inclusion criteria, with initial clinic follow-up obtained within approximately 6 weeks. Of the 173 patients, 104 (60.1%) were asymptomatic, 68 patients (39.3%) had mild, nonspecific neurological symptoms, and 1 patient (1.0%) had significant neurological symptoms. Of the asymptomatic patients, 3 patients (2.9%) had new CT findings and 1 of these patients (1.0%) underwent a change in treatment plan because of these findings. This change involved an additional clinic appointment and CT to monitor a 12-mm chronic subdural hematoma that ultimately resolved without treatment. Of the patients with mild, nonspecific neurological symptoms, 6 patients (8.8%) had new CT findings and 3 of these patients (4.4%) underwent a change in treatment plan because of these findings; none of these patients required surgical intervention. The single patient with significant neurological symptoms did not have any new CT findings.

Conclusions

Repeat outpatient CT of asymptomatic patients after nonoperative cerebral contusion and tSAH is very unlikely to demonstrate significant new pathology. Given the cost and radiation exposure associated with CT, imaging should be reserved for patients with significant symptoms or focal findings on neurological examination.

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David W. Roberts, Pablo A. Valdés, Brent T. Harris, Kathryn M. Fontaine, Alexander Hartov, Xiaoyao Fan, Songbai Ji, S. Scott Lollis, Brian W. Pogue, Frederic Leblond, Tor D. Tosteson, Brian C. Wilson and Keith D. Paulsen

Object

The aim of this study was to investigate the relationships between intraoperative fluorescence, features on MR imaging, and neuropathological parameters in 11 cases of newly diagnosed glioblastoma multiforme (GBM) treated using protoporphyrin IX (PpIX) fluorescence-guided resection.

Methods

In 11 patients with a newly diagnosed GBM, δ-aminolevulinic acid (ALA) was administered to enhance endogenous synthesis of the fluorophore PpIX. The patients then underwent fluorescence-guided resection, coregistered with conventional neuronavigational image guidance. Biopsy specimens were collected at different times during surgery and assigned a fluorescence level of 0–3 (0, no fluorescence; 1, low fluorescence; 2, moderate fluorescence; or 3, high fluorescence). Contrast enhancement on MR imaging was quantified using two image metrics: 1) Gd-enhanced signal intensity (GdE) on T1-weighted subtraction MR image volumes, and 2) normalized contrast ratios (nCRs) in T1-weighted, postGd-injection MR image volumes for each biopsy specimen, using the biopsy-specific image-space coordinate transformation provided by the navigation system. Subsequently, each GdE and nCR value was grouped into one of two fluorescence categories, defined by its corresponding biopsy specimen fluorescence assessment as negative fluorescence (fluorescence level 0) or positive fluorescence (fluorescence level 1, 2, or 3). A single neuropathologist analyzed the H & E–stained tissue slides of each biopsy specimen and measured three neuropathological parameters: 1) histopathological score (0–IV); 2) tumor burden score (0–III); and 3) necrotic burden score (0–III).

Results

Mixed-model analyses with random effects for individuals show a highly statistically significant difference between fluorescing and nonfluorescing tissue in GdE (mean difference 8.33, p = 0.018) and nCRs (mean difference 5.15, p < 0.001). An analysis of association demonstrated a significant relationship between the levels of intraoperative fluorescence and histopathological score (χ2 = 58.8, p < 0.001), between fluorescence levels and tumor burden (χ2 = 42.7, p < 0.001), and between fluorescence levels and necrotic burden (χ2 = 30.9, p < 0.001). The corresponding Spearman rank correlation coefficients were 0.51 (p < 0.001) for fluorescence and histopathological score, and 0.49 (p < 0.001) for fluorescence and tumor burden, suggesting a strongly positive relationship for each of these variables.

Conclusions

These results demonstrate a significant relationship between contrast enhancement on preoperative MR imaging and observable intraoperative PpIX fluorescence. The finding that preoperative MR image signatures are predictive of intraoperative PpIX fluorescence is of practical importance for identifying candidates for the procedure. Furthermore, this study provides evidence that a strong relationship exists between tumor aggressiveness and the degree of tissue fluorescence that is observable intraoperatively, and that observable fluorescence has an excellent positive predictive value but a low negative predictive value.