Faculty Bibliography

OBJECTIVE:Cranial fixation using pins during neurosurgical procedures is commonplace; however, parameters for the application of these devices in pediatric patients are not well defined. Variability in the thickness of the developing cranium necessitates age-specific considerations to reduce the risk of adverse events. To suggest possible guidelines for the use of cranial fixation pins in children, we surveyed neurosurgeons treating pediatric patients regarding their experience with such devices. METHODS:An Institutional Review Board-approved, 30-item multiple choice survey was provided by electronic mail to 605 neurosurgeons treating pediatric patients. The survey included specific questions regarding their experience with cranial fixation pins with respect to age ranges of patients, selection of pin size, type of pin pressure applied, and complications encountered. RESULTS:One hundred sixty-four (27%) responses were received. One hundred fifty-eight of the 164 (96%) neurosurgeons reported using cranial fixation pins in their pediatric practice. Forty-four of the 164 (27%) apply fixation pins in patients aged 1 to 2 years. Eighty-two (50%) apply pins in patients aged 2 to 3 years, and 89 (54%) apply pins in patients aged 3 to 4 years. For patients aged 2 to 5 years old, the majority of responders use between 10 and 40 pounds of pressure, whereas for those older than 5 years of age, most use between 30 and 40 pounds of pressure. After age 10, patients are treated as adults. Eighty-nine of the 164 (54%) responders reported complications directly related to the use of cranial fixation pins, including cranial fracture, epidural or subdural hematoma, scalp laceration, or cerebrospinal fluid leak. One hundred fifty-four of the 164 (94%) neurosurgeons responded that they are not aware of any standard guidelines for cranial fixation pin use in pediatric patients. Seven (4%) who stated that they were aware of guidelines did not describe where they obtained those guidelines. CONCLUSION/CONCLUSIONS:Cranial fixation pins are widely used among pediatric neurosurgeons in patients younger than 5 years old. Guidelines for their safe use are not well defined despite common use and experience of significant complications associated with such devices.

Giant cell tumors of the bone are rare, locally aggressive lesions that primarily affect the epiphyses of long bones. These tumors can occur in the skull, principally in the sphenoid and temporal bones. Symptoms of these tumors depend on their site of origin but typically include headache, pain, visual field defects, and conductive hearing loss. Histologically, these tumors consist of three cell types: osteoclast-like multinucleated giant cells; round mononuclear cells resembling monocytes; and spindle-shaped, fibroblast-like stromal cells. Radiographically, the tumors appear osteolytic and radiolucent without a sclerotic border. These tumors typically present in the third to fourth decades of life and rarely occur in patients under 20 years of age. The small number of studies of giant cell tumors of the skull has focused on the adolescent and adult populations. The authors report two cases of giant cell tumors of the skull in pediatric patients. In the first case, a 2-year-old girl presented with swelling behind the right ear. In the second case, a 7-week-old girl presented with a mass within the external auditory canal. Both patients underwent metastatic workup and biopsy procedures before resection of the tumor. Both case reports contribute to the literature of giant cell tumors of the skull by describing this condition in pediatric patients. To the authors' knowledge, these cases represent the youngest two patients with giant cell tumors of the skull yet described.

The authors report a case of a 7-month-old infant with a right lateral parietal scalp lesion intermittently leaking fluid similar to cerebrospinal fluid that histologically demonstrated meningothelial and glial cells. At surgical removal, however, no fibrous stalk or bony defect could be identified connecting the lesion with the intracranial compartment. While the embryologic mechanism of this lesion is unclear, the prognosis for normal neurological development appears excellent.

OBJECTIVE:To review the advent and evolution of the football helmet through historical, physiological, and biomechanical analysis. METHODS:We obtained data from a thorough review of the literature. RESULTS:Significant correlation exists between head injuries and the advent of the football helmet in 1896, through its evolution in the early to mid-1900s, and regulatory standards for both helmet use and design and tackling rules and regulations. With the implementation of National Operating Committee on Standards for Athletic Equipment standards, fatalities decreased by 74% and serious head injuries decreased from 4.25 per 100,000 to 0.68 per 100,000. Not only is the material used important, but the protective design also proves essential in head injury prevention. Competition among leading helmet manufacturers has benefited the ultimate goal of injury prevention. However, just as significant in decreasing the incidence and severity of head injury is the implementation of newer rules and regulations in teaching, coaching, and governing tackling techniques. CONCLUSION/CONCLUSIONS:Helmet use in conjunction with more stringent head injury guidelines and rules has had a tremendous impact in decreasing head injury severity in football. Modifications of current testing models may further improve helmet design and hence further decrease the incidence and severity of head injury sustained while playing football.

OBJECTIVE:To review head injury in football through historical, anatomic, and physiological analysis. METHODS:We obtained data from a thorough review of the literature. RESULTS:The reported incidence of concussion among high school football players dropped from 19% in 1983 to 4% in 1999. During the 1997 Canadian Football League season, players with a previous loss of consciousness in football were 6.15 times more likely to experience a concussion than players without a previous loss of consciousness (P < 0.05). Players with a previous concussion in football were 5.10 times more likely to experience a concussion than players without a previous concussion (P = 0.0001). With the implementation of National Operating Committee on Standards for Athletic Equipment standards, fatalities decreased by 74% and serious head injuries decreased from 4.25 per 100,000 to 0.68 per 100,000. CONCLUSION/CONCLUSIONS:Significant declines in both the incidence and severity of head injury have been observed. The enhanced safety records in football can be attributed to the application of more stringent tackling regulations as well as the evolving football helmet. The role of a neurosurgeon is critical in further head injury prevention and guidelines in sport.

We used repetitive transcranial magnetic stimulation (rTMS) to study visual naming in 14 patients with temporal lobe epilepsy. Ten had left hemisphere language by Wada testing and all experienced speech arrest with rTMS of the motor speech area in the left frontal lobe. One left-hander had speech arrest with stimulation of sites on both sides. Subjects were asked to name pictures or read words presented on a computer monitor. rTMS was delivered on half of the trials. Stimulation sites were the motor speech area in the left frontal lobe, the mirror site on the right, and the left and right mid superior and posterior temporal lobes. rTMS at left hemisphere sites caused more naming errors than did right hemisphere rTMS. All individual subjects, except two who had temporal lobe resections and the one with bilateral speech arrest, produced more naming errors with rTMS of left hemisphere sites. There was no significant effect on word reading. rTMS at the left hemisphere and right frontal sites produced reductions in reaction time for picture naming, but not for word reading. This was observed for both correct and incorrect responses. This study shows that left hemisphere rTMS can disrupt visual naming selectively.

In order to test a new repetitive transcranial magnetic stimulator, the Dantec MagPro, we administered transcranial magnetic stimulation (TMS) at 1 Hz and 125% of motor threshold for an average of 204 s (until the coil temperature reached 40 degrees C) and 20 Hz stimulation at 100% of motor threshold for 2 s every minute for 10 min, on different days to 10 healthy volunteers. We stimulated 6 scalp positions (primary motor area (M1) and sites 5 cm anterior and posterior on each hemisphere) with an 8-shaped coil. We tested immediate and delayed memory, verbal fluency, prolactin levels and EEG at the beginning of the study and after stimulation on each day. No abnormalities were found. Motor evoked potentials evoked with 1 Hz stimulation diminished progressively in amplitude, and 1 Hz stimulation of M1 caused inhibition lasting at least 1 min in 3 of 4 subjects who were tested with 0.1 Hz stimulation before and after the 1 Hz stimulation period. This did not occur with 20 Hz stimulation. Finger tapping frequency was tested at the beginning of the study and after TMS at each scalp site. Finger tapping rate data from 6 additional subjects who were stimulated in an identical fashion with a different stimulator were also analyzed. There was an increase in tapping rate after TMS which was independent of scalp site. This was most pronounced with 1 Hz stimulation at 125% of threshold and reached statistical significance in the hand contralateral to the stimulation. The results of this study indicate that rTMS with the MagPro stimulator is safe at specific combinations of intensity, frequency and train duration.