Measurement of aspiration pressure in cannula brain tumour biopsy and its correlation with ultrasonographic elastography.

BACKGROUND: Stereotactic brain biopsy is to perform the manual aspiration tissue biopsy using a cannula on a syringe under stereotactic guidance to provide histological confirmation. Excessive vacuum aspiration increases the risk of haemorrhage. Manual aspiration relies on the surgeon's experience while the minimum vacuum pressure is unknown. OBJECTIVES: 1. To assess the aspiration vacuum pressure range in cannula brain tumour biopsy; 2. To understand the correlation of ultrasound elastography data with the aspiration pressure. METHODS: This prospective study has recruited 10 patients for stereotactic brain tumour biopsy. With the use of ultrasound elastography, strain ratio of the lesion was assessed in real time before biopsy. Vacuum aspiration pressures were recorded using a T-connector pressure sensor during the stereotactic biopsy. RESULTS: A total of 11 biopsies were taken from 10 patients, including a bilateral biopsy for a patient with bifrontal lesions. The diagnostic yield was 100% in all the 10 patients with no symptomatic haemorrhage (but 2 subclinical haemorrhages in CT scan) nor infection. The vacuum pressures ranged from 40.34 to 65.61 kPa and the strain-ratio ranged from 0.405 to 2.74. Strain ratio of the lesion at the lower range required a lower range of aspiration pressure, whereas lesions of Strain ratio over 0.45 required a higher range of aspiration pressure. CONCLUSION: A vacuum pressure of 40 to 66 kPas is safe and adequate for biopsy of various types of tumours with heterogenous elastographic characters. Ultrasonographic elastography may be a real-time guide for the minimum vacuum pressure required for biopsy.

Assessing the neurological outcome of traumatic acute subdural hematoma patients with and without primary decompressive craniectomies.

BACKGROUND: We have investigated the impact of primary decompressive craniectomies on neurological outcomes after adjusting for other predictive variables. METHOD: We have collected data from trauma patients with acute subdural hematomas in a regional trauma center in Hong Kong over a 4-year period. Patient risk factors were investigated using logistic regression. RESULTS: Out of 464 patients with significant head injuries, 100 patients had acute subdural hematomas and were recruited for analysis. Forty-four percent of the patients achieved favorable neurological outcomes after 6 months. Favorable neurological outcomes at 1 year were related to age, pupil dilatation, and motor GCS scores at the time of admission. In the 34 patients who underwent evacuation of acute subdural hematomas, primary decompressive craniectomy was not associated with favorable neurological outcomes. CONCLUSION: Primary decompressive craniectomy failed to show benefit in terms of neurological outcomes and should be reserved for cases with uncontrolled intra-operative brain swelling.