Brent R. O'Neill

The history of external ventricular drainage

External ventricular drainage (EVD) is one of the most commonly performed neurosurgical procedures. It was first performed as early as 1744 by Claude-Nicholas Le Cat. Since then, there have been numerous changes in technique, materials used, indications for the procedure, and safety. The history of EVD is best appreciated in 4 eras of progress: development of the technique (1850-1908), technological advancements (1927-1950), expansion of indications (1960-1995), and accuracy, training, and infection control (1995-present). While EVD was first attempted in the 18th century, it was not until 1890 that the first thorough report of EVD technique and outcomes was published by William Williams Keen. He was followed by H. Tillmanns, who described the technique that would be used for many years. Following this, many improvements were made to the EVD apparatus itself, including the addition of manometry by Adson and Lillie in 1927, and continued experimentation in cannulation/drainage materials. Technological advancements allowed a great expansion of indications for EVD, sparked by Nils Lundberg, who published a thorough analysis of the use of intracranial pressure (ICP) monitoring in patients with brain tumors in 1960. This led to the application of EVD and ICP monitoring in subarachnoid hemorrhage, Reye syndrome, and traumatic brain injury. Recent research in EVD has focused on improving the overall safety of the procedure, which has included the development of guidance-based systems, virtual reality simulators for trainees, and antibiotic-impregnated catheters.

Image-guided cerebrospinal fluid shunting in children: catheter accuracy and shunt survival.

OBJECT Cerebrospinal fluid shunt placement has a high failure rate, especially in patients with small ventricles. Frameless stereotactic electromagnetic image guidance can assist ventricular catheter placement. The authors studied the effects of image guidance on catheter accuracy and shunt survival in children. METHODS Pediatric patients who underwent placement or revision of a frontal ventricular CSF shunt were retrospectively evaluated. Catheters were placed using either anatomical landmarks or image guidance. Preoperative ventricular size and postoperative catheter accuracy were quantified. Outcomes of standard and image-guided groups were compared. RESULTS Eighty-nine patients underwent 102 shunt surgeries (58 initial, 44 revision). Image guidance was used in the placement of 56 shunts and the standard technique in 46. Shunt failure rates were not significantly different between the standard (22%) and image-guided (25%) techniques (p = 0.21, log-rank test). Ventricular size was significantly smaller in patients in the image-guided group (p < 0.02, Student t-test) and in the surgery revision group (p < 0.01). Small ventricular size did not affect shunt failure rate, even when controlling for shunt insertion technique. Despite smaller average ventricular size, the accuracy of catheter placement was significantly improved with image guidance (p < 0.01). Shunt accuracy did not affect shunt survival. CONCLUSIONS The use of image guidance improved catheter tip accuracy compared with a standard technique, despite smaller ventricular size. Failure rates were not dependent on shunt insertion technique, but an observed selection bias toward using image guidance for more at-risk catheter placements showed failure rates similar to initial surgeries.

Incidence of seizures on continuous EEG monitoring following traumatic brain injury in children

OBJECT Seizures may cause diagnostic confusion and be a source of metabolic stress after traumatic brain injury (TBI) in children. The incidence of electroencephalography (EEG)-confirmed seizures and of subclinical seizures in the pediatric population with TBI is not well known. METHODS A routine protocol for continuous EEG (cEEG) monitoring was initiated for all patients with moderate or severe TBI at a Level 1 pediatric trauma center. Over a 3.5-year period, all patients with TBI who underwent cEEG monitoring, both according to protocol and those with mild head injuries who underwent cEEG monitoring at the discretion of the treating team, were identified prospectively. Clinical data were collected and analyzed. RESULTS Over the study period, 594 children were admitted with TBI, and 144 of these children underwent cEEG monitoring. One hundred two (71%) of these 144 children had moderate or severe TBI. Abusive head trauma (AHT) was the most common mechanism of injury (65 patients, 45%) in children with cEEG monitoring. Seizures were identified on cEEG in 43 patients (30%). Forty (93%) of these 43 patients had subclinical seizures, including 17 (40%) with only subclinical seizures and 23 (53%) with both clinical and subclinical seizures. Fifty-three percent of patients with seizures experienced status epilepticus. Age less than 2.4 years and AHT mechanism were strongly correlated with presence of seizures (odds ratios 8.7 and 6.0, respectively). Those patients with only subclinical seizures had the same risk factors as the other groups. The presence of seizures did not correlate with discharge disposition but was correlated with longer hospital stay and intensive care unit stay. CONCLUSIONS Continuous EEG monitoring identifies a significant number of subclinical seizures acutely after TBI. Children younger than 2.4 years of age and victims of AHT are particularly vulnerable to subclinical seizures, and seizures in general. Continuous EEG monitoring allows for accurate diagnosis and timely treatment of posttraumatic seizures, and may mitigate secondary injury to the traumatized brain.

Hydrogel coil–related delayed hydrocephalus in patients with unruptured aneurysms

OBJECT Because of high recanalization rates associated with wide-necked intracranial aneurysms treated with bare platinum coils, hydrogel coils (HydroCoil, MicroVention, Inc.) have been developed. Hydrogel coils undergo progressive expansion once exposed to the physiological environment of blood and increase overall aneurysm filling. METHODS The authors retrospectively reviewed their series of patients with unruptured aneurysms treated between 1998 and 2006 and who underwent placement of bare platinum and hydrogel coils for cerebral aneurysms. They examined the incidence of delayed hydrocephalus as related to coil type. In a subgroup of patients in which preand postprocedure CT and MR imaging studies were available, the authors quantitatively analyzed the ventricular size change after hydrogel coils were placed. RESULTS Four of 29 patients treated with hydrogel coils developed symptomatic hydrocephalus 2-6 months after the intervention compared with 0 of 26 treated with bare platinum coils alone. The difference in ventricular size between the subgroups in which pre- and postprocedure imaging was performed was found to be statistically significant (p < 0.05). All 4 HydroCoil-treated patients in whom hydrocephalus developed required placement of a shunt. CONCLUSIONS A 14% incidence (95% confidence interval 3.9-31.7%) of hydrocephalus in patients with unruptured aneurysm undergoing embolization with hydrogel coils was discovered. This incidence is much higher than previously reported. The mechanism by which hydrogel coils may induce hydrocephalus remains poorly understood.

Use of magnetic resonance imaging to detect occult spinal dysraphism in infants

OBJECTIVE Cutaneous stigmata or congenital anomalies often prompt screening for occult spinal dysraphism (OSD) in asymptomatic infants. While a number of studies have examined the results of ultrasonography (US) screening, less is known about the findings when MRI is used as the primary imaging modality. The object of this study was to assess the results of MRI screening for OSD in infants. METHODS The authors undertook a retrospective review of all infants who had undergone MRI of the lumbar spine to screen for OSD over a 6-year period (September 2006-September 2012). All images had been obtained on modern MRI scanners using sequences optimized to detect OSD, which was defined as any fibrolipoma of the filum terminale (FFT), a conus medullaris ending at or below the L2-3 disc space, as well as more complex lesions such as lipomyelomeningocele (LMM). RESULTS Five hundred twenty-two patients with a mean age of 6.2 months at imaging were included in the study. Indications for imaging included isolated dimple in 235 patients (45%), asymmetrically deviated gluteal cleft in 43 (8%), symmetrically deviated (Y-shaped) gluteal cleft in 38 (7%), hemangioma in 28 (5%), other isolated cutaneous stigmata (subcutaneous lipoma, vestigial tail, hairy patch, and dysplastic skin) in 31 (6%), several of the above stigmata in 97 (18%), and congenital anomalies in 50 (10%). Twenty-three percent (122 patients) of the study population had OSD. Lesions in 19% of these 122 patients were complex OSD consisting of LMM, dermal sinus tract extending to the thecal sac, and lipomeningocele. The majority of OSD lesions (99 patients [81%]) were filar abnormalities, a group including FFT and low-lying conus. The rate of OSD ranged from 12% for patients with asymmetrically deviated gluteal crease to 55% for those with other isolated cutaneous stigmata. Isolated midline dimple was the most common indication for imaging. Among this group, 20% (46 of 235) had OSD. There was no difference in the rate of OSD based on dimple location. Those with OSD had a mean dimple position of 15 mm (SD 11.8) above the coccyx. Those without OSD had a mean dimple position of 12.2 mm (SD 19) above the coccyx (p = 0.25). CONCLUSIONS The prevalence of OSD identified with modern high-resolution MRI screening is significantly higher than that reported with US screening, particularly in patients with dimples. The majority of OSD lesions identified are FFT and low conus. The clinical significance of such lesions remains unclear.

Image-guided cerebrospinal fluid shunting in children

OBJECT Cerebrospinal fluid shunt placement has a high failure rate, especially in patients with small ventricles. Frameless stereotactic electromagnetic image guidance can assist ventricular catheter placement. The authors studied the effects of image guidance on catheter accuracy and shunt survival in children. METHODS Pediatric patients who underwent placement or revision of a frontal ventricular CSF shunt were retrospectively evaluated. Catheters were placed using either anatomical landmarks or image guidance. Preoperative ventricular size and postoperative catheter accuracy were quantified. Outcomes of standard and image-guided groups were compared. RESULTS Eighty-nine patients underwent 102 shunt surgeries (58 initial, 44 revision). Image guidance was used in the placement of 56 shunts and the standard technique in 46. Shunt failure rates were not significantly different between the standard (22%) and image-guided (25%) techniques (p = 0.21, log-rank test). Ventricular size was significantly smaller in patients in the image-guided group (p < 0.02, Student t-test) and in the surgery revision group (p < 0.01). Small ventricular size did not affect shunt failure rate, even when controlling for shunt insertion technique. Despite smaller average ventricular size, the accuracy of catheter placement was significantly improved with image guidance (p < 0.01). Shunt accuracy did not affect shunt survival. CONCLUSIONS The use of image guidance improved catheter tip accuracy compared with a standard technique, despite smaller ventricular size. Failure rates were not dependent on shunt insertion technique, but an observed selection bias toward using image guidance for more at-risk catheter placements showed failure rates similar to initial surgeries.

Image-guided cerebrospinal fluid shunting in children: catheter accuracy and shunt survival: Clinical article

OBJECT Cerebrospinal fluid shunt placement has a high failure rate, especially in patients with small ventricles. Frameless stereotactic electromagnetic image guidance can assist ventricular catheter placement. The authors studied the effects of image guidance on catheter accuracy and shunt survival in children. METHODS Pediatric patients who underwent placement or revision of a frontal ventricular CSF shunt were retrospectively evaluated. Catheters were placed using either anatomical landmarks or image guidance. Preoperative ventricular size and postoperative catheter accuracy were quantified. Outcomes of standard and image-guided groups were compared. RESULTS Eighty-nine patients underwent 102 shunt surgeries (58 initial, 44 revision). Image guidance was used in the placement of 56 shunts and the standard technique in 46. Shunt failure rates were not significantly different between the standard (22%) and image-guided (25%) techniques (p = 0.21, log-rank test). Ventricular size was significantly smaller in patients in the image-guided group (p < 0.02, Student t-test) and in the surgery revision group (p < 0.01). Small ventricular size did not affect shunt failure rate, even when controlling for shunt insertion technique. Despite smaller average ventricular size, the accuracy of catheter placement was significantly improved with image guidance (p < 0.01). Shunt accuracy did not affect shunt survival. CONCLUSIONS The use of image guidance improved catheter tip accuracy compared with a standard technique, despite smaller ventricular size. Failure rates were not dependent on shunt insertion technique, but an observed selection bias toward using image guidance for more at-risk catheter placements showed failure rates similar to initial surgeries.