George J. Alker

Computer-assisted stereotactic microsurgery for the treatment of intracranial neoplasms.

This paper describes a stereotactic CO2 laser system for the removal of intra-axial, intracranial neoplasms. The volume of the neoplasm is transferred into stereotactic space by computer reconstruction of data derived by computed tomography (CT) performed under stereotactic conditions. The tumor volume is sliced in a plane orthogonal to the surgical approach, and slices at specific distances from the focal point of the stereotactic frame are displayed on a graphics monitor in the operating suite along with a cursor representing the position of the surgical laser. Laser vaporization of sequential slices of the tumor results in a cavity, the formation of which is monitored by anteroposterior and lateral roentgenograms. Fifteen stereotactic laser procedures have been performed on 13 patients, and the results are discussed. By this method, it is theoretically possible to remove all of an intracranial neoplasm detected by CT scanning.

A computed tomographic stereotactic adaptation system.

An adaptation to render an existing popular stereotactic apparatus compatible with computed tomography (CT) is described. A localization system attaches to the stereotactic head holder and a simple computer program allows considerable accuracy in the translation of CT data into stereotactic space in the operating room.

A microstereotactic approach to deep-seated arteriovenous malformations

Abstract This report describes an open stereotactic approach for the treatment of a deep-seated arteriovenous malformation. Stereoscopic arteriography and a stereotactically directed carbon dioxide laser beam were utilized for total excision of the malformation.

Myelographic demonstration of lumbosacral nerve root avulsion.

Avulsion of cervical nerve roots by A traction injury to the shoulder girdle is well known (1, 7, 12), but, on the other hand, traumatic avulsion of lumbosacral nerve roots is exceedingly rare. A search of the literature revealed only 3 reported cases to date of this condition with myelographic demonstration. The first was described by Finney and Wulfman in 1960 (3), and 2 more were reported recently by Goodell (4). The 2 case reports which form the basis of this communication describe the characteristic radiographic and clinical features of lumbar or sacral nerve root avulsion. Case I: F. H., a 22-year-old man, was admitted to a local hospital on Oct. 9, 1962, following an auto accident in which he sustained cerebral concussion and fractures of the right upper and lower extremities. The pelvic fractures included separation of the right sacroiliac joint and of the pubic symphysis with marked deformity (Fig. 1). Due to the numerous fractures, a complete neurological examination could not be carried out. It...

An overview of CT based stereotactic systems for the localization of intracranial lesions.

Computed tomography, with its inherent accuracy in identifying and localizing intracranial lesions, has been adapted by several groups for use in stereotactic neurosurgical procedures. The systems range from the use of data obtained on conventional CT scans to installation of a dedicated CT scanner in the operating room equipped for stereotactic surgery. Although the GE-8800 scanner is used most frequently, others are also suitable. Adaptations of standard commercially available stereotactic frames are used by some groups while others designed frames specifically for this purpose. The paper is an overview of systems described in the literature to date.

The radiology of cerebrospinal fluid shunts and their complications

Abstract The three commonly used types of cerebrospinal fluid shunts are ventriculo-cisternal, ventriculo-atrial, and ventriculo-peritoneal shunts. These consist of catheters, valves, flushing devices and reservoirs. The radiographic features of several shunt systems are described. The radiographically recognizable complications of cerebrospinal fluid shunts are cranial, cardiovascular, and abdominal. The cranial complications include displacement and disconnection of the ventricular catheter. Cardiovascular changes include retraction of catheters, embolism and thrombosis of vessels and, rarely, damage to the cardiac wall. Migration of catheters out of or into the abdominal cavity and occasional volvulus or bowel perforation represent the possible abdominal complications. All of these complications ultimately lead to cessation of function of the shunt.

Neurosurgery in a different society: the People??s Republic of China

An interdisciplinary clinical neurosciences delegation representing the International Committee of the Congress of Neurological Surgeons visited the neurosurgical departments of major teaching hospitals in five cities of the Peoples Republic of China. This report describes the clinical and research activities observed, with reference to the unique social, political, economic, and cultural environment in China. Although facilities and equipment are limited, diagnostic accuracy and surgical technique are excellent. Results for certain disorders seemed comparable to those obtained in western neurosurgical centers. Given the clinical expertise of our Chinese colleagues and the large numbers of cases treated in Chinese medical centers, a significant contribution to neurosurgical knowledge can be expected from the exchange of information and future collaboration that have now become possible.

An effective surrogate for impact studies

Nineteen unembalmed (fresh) cadavers were used in 21 experiments to test restraint systems in automobile impact studies. Some were mounted in a rearward firing sled; others were placed in standard cars during collisions. Prior to and after testing, each cadaver was evaluated. After each experiment a postmortem examination was performed. High-speed registering cameras (1,000 to 2,000 frames per second) were used and multiple telemetric recordings were made. The radiographic and pathologic changes were similar to those seen in patients following high-velocity accidents. Results were compared with those of car accident victims admitted dead on arrival to one of our hospitals. This study is a progress report. The results are being used to improve existing restraint systems and to evaluate experimental models.

False Positive Dynamic Imaging of the Cerebral Circulation Due to a Congenital Anomaly

False positive dynamic imaging of the cerebral circulation simulating vascular occlusive disease resulted from a clinically insignificant congenital variation in several patients at our institutions. The anomaly consisted of the asymmetrical caliber of the internal carotid and proximal anterior cerebral arteries. The 1 mm difference in the diameter of the internal carotid arteries was sufficient to be appreciated on dynamic imaging. The frequency of this anomaly was found to be 5% in a series of 200 bilateral carotid angiograms.