Dural echoencephalography

History of intraoperative ultrasound

Intraoperative ultrasound (IOUS) using A-mode or non-real-time B-mode imaging started in the 1960s; however, it was not widely accepted mainly because of difficulty in image interpretation. In the late 1970s, IOUS became one of the topics in the surgical communities upon the introduction of high-frequency real-time B-mode ultrasound. Special probes for operative use were developed. In the 1980s, all over the world the use of IOUS spread to a variety of surgical fields, such as hepatobiliary pancreatic surgery, neurosurgery, and cardiovascular surgery. IOUS changed hepatic surgery dramatically because IOUS was the only modality that was capable of delineating and examining the interior of the liver during surgery. After 1990, color Doppler imaging and laparoscopic ultrasound were incorporated into IOUS. Currently, IOUS is considered an indispensable operative procedure for intraoperative decision-making and guidance of surgical procedures. For better surgical practice, education of surgeons in the use of ultrasound is the most important issue.

A tribute to Dr. A. Earl Walker

Doctor Walker died on January 1, 1995, at the age of 87 years. His contributions to neuroscience and neurosurgery are presented and discussed, together with his impact on national and international organizations of neurosurgery. A short account of his background and professional career is given, with emphasis on his 25 years at The Johns Hopkins Hospital as Chief of Neurosurgery.

Intraoperative ultrasound-guided biopsy of intracranial lesions: comparison with freehand biopsy

Achieving the required accuracy during such relatively straightforward procedures as tumour biopsy or abscess aspiration remains a challenge especially for the more junior neurosurgeon. A study comparing freehand biopsy with ultrasound-guided biopsy is presented. The use of intraoperative ultrasound increases the accuracy at the expense of a slightly longer operating time. Diagnostic tissue was always obtained using this technique.

The value of intraoperative ultrasound in neurosurgery

Intraoperative ultrasound is not a technique which has been widely accepted by neurosurgeons in this country, not least because bulky probes and machines become more of a hindrance than an asset in theatre. The development of new smaller probes, including ones small enough to visualize the brain through a conventional burr-hole has rekindled interest in this subject. Its use for guidance in tumour biopsy, cyst aspiration and catheter placement, as well as volume estimations and determining the completeness of tumour resection, are outlined. The ability to recognize peri-operative haemorrhage is demonstrated.

Intraoperative cranial sonography

The use of real time ultrasound in the neurosurgical operating room can enhance the ability to localize intracerebral masses, allow accurate needle biopsies, diminish the amount of potential damage to normal brain tissue, show the results of tumor resection, and help in the placement of ventricular and cyst shunts. The end result makes the surgical procedure faster, safer, and more accurate.

Ultrasound-guided biopsy for deep-seated brain tumors

✓ An easy, accurate, and safe biopsy technique for deep-seated brain tumors using a newly devised real-time ultrasonic apparatus is presented. Three lesions, one large pituitary adenoma and two pineal region tumors, were biopsied successfully by this technique.

Intraoperative use of real-time ultrasonography in neurosurgery

The authors' experience with the intraoperative use of real-time ultrasonography during 21 neurosurgical procedures is reported. These procedures include neoplasm surgery in 18 cases, treatment of an arteriovenous malformation in one case, and ventricular catheter placement for hydrocephalus in two cases. In each of the neoplasm cases, the tumors were imaged just as well through the intact dura as on the brain surface itself. There were no cases in which the pathology could not easily be identified. The use of portable intraoperative ultrasonography in sterile coverings has proven to be extremely useful in localizing small subcortical neoplasms, as well as locating the solid and cystic portions of deep lesions. It has assisted in guiding needles for both biopsy and aspiration. It has also accurately identified and guided Silastic catheters during their placement in the ventricular system in cases of hydrocephalus. The authors have found real-time ultrasonography to be an important new tool in the operating room and will continue to rely on its imaging ability during selected procedures in the future.

Experimental study of high-resolution ultrasound imaging of hemorrhage, bone fragments, and foreign bodies in head trauma

The accuracy of high-resolution ultrasound scans in detecting foreign bodies and hemorrhage within the brain was evaluated by comparison with computerized tomography (CT) scans and gross pathology. The test lesions were blood and foreign bodies consisting of bone, wood, and metal placed in the brain of an experimental animal. High-resolution ultrasound scans (10 MHz) performed in coronal and sagittal planes accurately delineated the position and spatial orientation of these foreign bodies and hemorrhage. Both hemorrhage and foreign bodies were echogenic compared to normal, hypoechoic brain parenchyma. Metal fragments had a highly characteristic echo pattern caused by sound reverberation within the object. Acute intracerebral hemorrhage produced an ultrasound image consisting of sharply circumscribed homogeneous echoes. The sonographic shape of intracerebral hemorrhage correlated closely with the area of increased density seen on the CT scan. High-resolution ultrasonography accurately delineated experimentally produced components of head trauma and may prove useful as an intraoperative imaging technique to facilitate surgery in head-injured patients.

Experimental intraoperative localization of retained intracerebral bone fragments using transdural ultrasound

Precise intraoperative localization of retained bone fragments and foreign bodies avoids extensive brain disseciton, cerebral edema, damage to vital structures, incomplete debridement, and prolonged surgical procedures. Such localization after head trauma is often hampered by cerebral distortion, previous incomplete debridement, fragment migration, and surgical draping. Our intraoperative technique of transdural A-scanning using aspiration-biopsy transducers precisely localized 3.5-mm fragments without damage to underlying cortical tissue and vessles. Transdural A-mode echoencephalography was found to be more reliable for intracerebral depth estimations but epidural B-mode sonography was more useful for determining the size of fragments. Transdural ultrasound offered an intraoperative alternative to stereotaxic localization of retained bone fragments in experimental head trauma.

Stereotactic exploration of brain tumours by ultrasound

A report upon a new technique for investigation of brain tumour anatomy by means of stereotactically directed ultrasound is presented with some illustrative cases. Information obtained with this technique has been found useful when deciding the treatment program for the tumour.