Peter A. Heppner

Paediatric central nervous system tumours in a New Zealand population: A 10-year experience of epidemiology, management strategies and outcomes

We analysed 166 cases of paediatric central nervous system tumour presenting to Auckland City and Starship Childrens Hospital, New Zealand, between 1995 and 2004. The purpose of this study was to perform an audit of paediatric neurosurgical practice in the upper North Island of New Zealand with the objective of assessing patient presentation, demographics, and modality and efficacy of therapy. The overall incidence of central nervous system tumours was 3.42/100,000/year. The incidence rate of medulloblastoma for Maori was over double that for European New Zealanders. Tumour clearance was attempted in 81.3% of patients. Some type of adjunct therapy was received by 45.2% of patients. Overall, 60.8% of patients had satisfactory or good results. Survival rates for pilocytic astrocytoma and ependymoma were consistent with previous studies. Survival data for medulloblastoma demonstrate improved outcomes with complete resection of tumour and with a specialist paediatric neurosurgeon compared with general neurosurgeons. Recent management changes have led to improved outcomes.

Transfer of intubated patients with traumatic brain injury to Auckland City Hospital.

Background:  Delays in patient transfer to definitive neurosurgical care after traumatic brain injury are important in determining neurological outcome. The efficiency of interhospital transfer of patients to Auckland City Hospital (ACH) was analysed and compared with international standards.

Implantable ICP Monitor for Improved Hydrocephalus Management

BACKGROUND Hydrocephalus patients are commonly treated by insertion of ventriculoperitoneal shunts, but these have high complication rates. Monitoring of shunt and patient condition can be achieved through measuring intracranial pressure (ICP). Significant zero drift has limited previous developments towards a long-term implantable ICP monitor. We present a new implantable solid-state pressure sensor system appropriate for chronic (lifetime) monitoring of ICP. MATERIALS AND METHODS Initial designs of the proposed ICP system were realised and the pressure sensor catheter underwent bench-top tests to analyse its characteristics. A drift rig was constructed for the long-term analysis of the sensors zero drift. The pressure sensor catheter was used to continuously monitor blood pressure in rats. RESULTS Three potential design solutions were realised: a standalone sensor, the sensor unit in line with a shunt system, and the sensor unit fully integrated into the shunt valve housing. Initial stability results across 46 days show a maximum drift of less than 2 mmHg and a minimum drift of less than 0.2 mmHg. CONCLUSION Initial experience with the new implantable solid-state pressure sensor system confirms its suitability for chronic pressure monitoring. The device is promising for providing vital information on shunt and patient condition.

MRI interactions of a fully implantable pressure monitoring device

To investigate the potential patient risk and interactions between a prototype implantable pressure monitoring device and a 3T clinical magnetic resonance imaging (MRI) machine to guide device design towards MR Conditional safety approval.

Acute hydrocephalus secondary to herpes simplex type II meningitis

A 34-year-old woman presented with a rapid onset of meningitic symptoms. Cerebrospinal fluid (CSF) from a lumbar puncture revealed a leucocytosis with a preponderance of monocytes, elevated protein and reduced glucose. Herpes simplex virus (HSV) type II was subsequently confirmed by polymerase chain reaction (PCR) of CSF. The patients level of consciousness deteriorated and a CT scan revealed hydrocephalus. The patient required placement of an external ventricular drain for 5 days; however, she made a full recovery without specific antiviral therapy. This is the first reported case of hydrocephalus secondary to isolated HSV type II meningitis.

Encephalocoele : epidemiological variance in New Zealand

Considerable variation in the epidemiology of encephalocoeles throughout the world has been described in previous studies. We analysed 46 cases of encephalocoele presenting to Auckland and Starship Childrens Hospital over the last 25 years to determine if our experience differed from that seen in a typical Western population, and to determine if there was variation between the different racial groups within New Zealand. The overall incidence of encephalocoeles in the area serviced by the neurosurgical services of Auckland and Starship Childrens Hospitals was 1 in 13,418 births. This rate is at the higher end of the incidence spectrum compared with previous series. Overall, New Zealand appears to demonstrate a typical Western distribution of encephalocoele location. In people of Pacific Island descent, both the rate of encephaloceles (1 per 8,873 births) and the percentage of sincipital lesions (44%) differed from the rest of the population. Additionally, a higher than expected proportion of sincipital encephalocoeles was seen in male babies (5:1 male to female ratio). In most other regards our population resembles that of western cohorts published in the literature.

Implantable Multi-Modal Sensor to Improve Outcomes in Hydrocephalus Management

Hydrocephalus is the single most common pediatric neurosurgical problem worldwide. Current treatment of this life-threatening disorder involves diverting excess fluid from the ventricles of the brain via a prosthetic shunt. While many hydrocephalus sufferers rely heavily on their ventriculo-distal shunt to maintain a healthy intracranial pressure, shunts carry a high risk of failure. Current methods of assessing shunt patency are performed within the hospital, and many patients and their families feel bound to remaining within close proximity of a hospital in order to receive timely medical intervention in the event of a shunt failure. There is a need for a system which can detect shunt malfunction, simply and reliably. We present a novel method of obtaining flow measurements from a piezoresistive pressure transducer. This builds on an earlier development of obtaining simultaneous temperature and pressure measurement from the single ultra-miniature solid-state transducer. The flow measurement system is capable of measurements in the range 0-35 ml/h, typical of the fluid flow rates through a hydrocephalus shunt. Within the flow range 0-14 ml/hour the resolution is 2 ml/hour. For flow rates greater than 16 ml/hour the resolution is 5 ml/hour. Employing a thermal flow sensing technique, the maximum heating of the local fluid is 0.65 ± 0.02 °C. The flow signal is independent of ambient temperature. The sensor would be implanted in the shunt to allow the detection of the flow rate of fluid through it, enabling the clinician to measure the patency of a shunt in real time.

A New Tool for the Neurointensive Care Unit: Simultaneous Measurement of Temperature From a Catheter-Tip Pressure Sensor

Traumatic brain injury is a leading cause of death and permanent disability throughout the world. Over the past 15 years, basic science has made important advances in the understanding of this condition. These advances have not, however, translated into treatment of clinically proven benefit. It has been suggested that individualized care for brain injured patients should include improved monitoring of brain function. For clinical gains to be made, clinicians and researchers require appropriate diagnostic and monitoring tools. In this paper, we describe the novel method of acquiring temperature measurement from a pressure sensor. The method allows concurrent measurements of pressure and temperature. The temperature measurement has a sensitivity of 85.08 mV/°C, across the measurement range 20 °C-45 °C. The time constant of the temperature sensor is 610 ± 55 ms. The mean cross-sensitivity of the temperature signal to changes in pressure is 0.74 m°C/mmHg within the typical physiological pressure range (0-160 mmHg). A method to compensate for this pressure-related error is described. We have evaluated the accuracy of the temperature measurement and the long-term stability of 13 sensors over a period of 28 days. The mean difference between temperature measurements made from the sensors and those made from the reference sensor was <;0.2 °C.

Metastatic choriocarcinoma induced separate simultaneous intracerebral haemorrhages: a very rare occurrence and its novel association with Klinefelter syndrome.

Non-traumatic separate simultaneous intracerebral haemorrhages (SSIHs) are rare. Relevant aetiologies are diverse and their diagnosis challenging. We report a unique case of SSIH in an 18-year-old male with a background of previously undiagnosed testicular choriocarcinoma and Klinefelter syndrome. The patient was admitted to Auckland City Hospital with headaches, drowsiness and vomiting. A CT scan revealed SSIH in a background of tumorous lesions. His β human chorionic gonadotropin titre was elevated at 355 000 IU/L. The SSIH and the associated tumorous lesions were acutely surgically resected and the patient started on bleomycin, etoposide and cisplatin combination chemotherapy with excellent results. In this article, we underline choriocarcinoma as a rare aetiology of SSIH and present an example of the clinical presentation, investigation and management of this very rare pathological entity.

Intracranial temperature and pressure measurement: In vitro temperature sensing characteristics of the dual sensing element

A pressure sensor has been used to measure temperature concurrently. We have designed, and characterized the measurement of temperature from the same sensor to allow simultaneous monitoring of intracranial temperature and pressure. The temperature measurement has a sensitivity of 85.08 mV/°C across the measurement range 20-45 °C. The time constant of the temperature sensor is 150 ms. We have evaluated the accuracy of the temperature measurement and the long term drift of 13 sensors over 28 days. The mean difference of the temperature measurements from the reference measurements was less than 0.2 °C.