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Kim Burchiel

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L. Fernando Gonzalez, Neil R. Crawford, Robert H. Chamberlain, Luis E. Perez Garza, Mark C. Preul, Volker K. H. Sonntag and Curtis A. Dickman

Object. The authors compared the biomechanical stability resulting from the use of a new technique for occipitoatlantal motion segment fixation with an established method and assessed the additional stability provided by combining the two techniques.

Methods. Specimens were loaded using nonconstraining pure moments while recording the three-dimensional angular movement at occiput (Oc)—C1 and C1–2. Specimens were tested intact and after destabilization and fixation as follows: 1) Oc—C1 transarticular screws plus C1–2 transarticular screws; 2) occipitocervical transarticular (OCTA) plate in which C1–2 transarticular screws attach to a loop from Oc to C-2; and (3) OCTA plate plus Oc—C1 transarticular screws.

Occipitoatlantal transarticular screws reduced motion to well within the normal range. The OCTA loop and transarticular screws allowed a very small neutral zone, elastic zone, and range of motion during lateral bending and axial rotation. The transarticular screws, however, were less effective than the OCTA loop in resisting flexion and extension.

Conclusions. Biomechanically, Oc—C1 transarticular screws performed well enough to be considered as an alternative for Oc—C1 fixation, especially when instability at C1–2 is minimal. Techniques for augmenting these screws posteriorly by using a wired bone graft buttress, as is currently undertaken with C1–2 transarticular screws, may be needed for optimal performance.

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Jeffrey S. Henn, G. Michael Lemole Jr., Mauro A. T. Ferreira, L. Fernando Gonzalez, Mark Schornak, Mark C. Preul and Robert F. Spetzler

✓ The goal of this study was to develop a new method for neurosurgical education based on interactive stereoscopic virtual reality (ISVR). Interactive stereoscopic virtual reality can be used to recreate the three-dimensional (3D) experience of neurosurgical approaches much more realistically than standard educational methods. The demonstration of complex 3D relationships is unrivaled and easily combined with interactive learning and multimedia capabilities.

Interactive stereoscopic virtual reality permits the accurate recreation of neurosurgical approaches through integration of several forms of stereoscopic multimedia (video, interactive anatomy, and computer-rendered animations). The content explored using ISVR is obtained through a combination of approach-based cadaver dissections, live surgical images and videos, and computer-rendered animations. These media are combined through an interactive software interface to demonstrate key aspects of a neurosurgical approach (for example, patient positioning, draping, incision, individual surgical steps, alternative steps, relevant anatomy). The ISVR platform is designed for use on a desktop personal computer with newly developed, inexpensive, platform-independent shutter glasses.

Interactive stereoscopic virtual reality has been used to capture the anatomy and methods of several neurosurgical approaches. In this paper the authors report their experience with ISVR and describe its potential advantages. The success of a neurosurgical approach is contingent on the mastery of complex, 3D anatomy. A new technology for neurosurgical education, ISVR can improve understanding and speed the learning process. It is an effective tool for neurosurgical education, bridging the substantial gap between textbooks and intraoperative training.

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Mark C. Preul and William Feindel

✓ Wilder Penfield and Harvey Cushing created legacies to neurosurgery, both in terms of those they trained and in their philosophical approach to the field. Their biographies provide only brief comments on their relationship without any thorough examination of their personal correspondence. In this article the Penfield—Cushing relationship is examined through an analysis of their unpublished personal letters. The Penfield—Cushing correspondence is a treasure for neurosurgery; it provides remarkable insight into the embryonic period of the discipline and into the relationship of two of the most influential figures in modern neurosurgery.

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Jeffrey A. Brown, Catherine Coursaget, Mark C. Preul and Devdutta Sangvai

✓ In his 1756 text, Observations pratiques sur les maladies de l'urèthre et sur plusiers faits convulsifs, Nicolas André coined the term “tic douloureux.” He believed that this pain originated from compression of facial sensory peripheral nerves. Using scientific observation and experimentation to confirm this hypothesis, he reproduced the tic pain and treated it by using careful efforts to remove adhesions from the nerve with a caustic solution of mercury water. Believing that recurrence of the pain was a result of early closure of the wound, with recompression of the nerve being the direct cause, André prevented recompression by ensuring open wound drainage. André's surgical technique of using cauterizing stones ensured that there was minimal blood loss and little danger of rebleeding and recompression of the nerve by an accumulated blood clot. His case reports include lengthy follow-up periods that documented the benefits of his procedures, which were confirmed by testimonials from uninvolved colleagues. Although remembered for the two words, “tic douloureux,” Nicolas André has long been ignored for his prescient treatment and scientific analysis of a disease for which the modern standard of care has only been defined during the last generation.

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Mark C. Preul, William Feindel, T. Forcht Dagi, Joseph Stratford and Gilles Bertrand

✓ The contributions of Arthur Elvidge (1899–1985), Wilder Penfield's first neurosurgical recruit, to the development of neurosurgery have been relatively neglected, although his work in brain tumors extended the previous work of Percival Bailey and Harvey Cushing. He published rigorous correlations of clinical and histological information and formulated a revised, modern nosology for neuroepithelial tumors, including a modern histological definition of glioblastoma multiforme. Well ahead of his time, he believed that glioblastoma was not strictly localized and was the first to comment that the tumor frequently showed “satellitosis.” He was the first neurosurgeon in North America to use angiography as a radiographic aid in the diagnosis of cerebrovascular disease. Having studied with Egas Moniz, he was the first to detail the use of angiographic examinations specifically for demonstrating cerebrovascular disorders, believing that it would make possible routine surgery of the intracranial blood vessels. Seeking to visualize all phases of angiography, he was the impetus behind the design of one of the first semi-automatic film changers. Elvidge and Egas Moniz made the first observations on thrombosis of the carotid vessels independently of each other. Elvidge elucidated the significance of embolic stroke and commented on the ischemic sequelae of subarachnoid hemorrhage. Besides his contributions to neurosurgery, he codiscovered the mode of transmission of poliomyelitis. Elvidge's soft-spoken manner, his dry wit and candor, mastery of the understatement, love of exotic travel, and consummate dedication to neurosurgery made him a favorite of patients, neurosurgery residents, nurses, and other hospital staff. His accomplishments and example as teacher and physician have become part of neurosurgery's growing legacy.

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Mark C. Preul, Richard Leblanc, Fernando Cendes, Francois Dubeau, David Reutens, Roberto Spreafico, Giorgio Battaglia, Massimo Avoli, Pierre Langevin, Douglas L. Arnold and Jean-Guy Villemure

✓ Cerebral dysgenesis is a subject of interest because of its relationship to cerebral development and dysfunction and to epilepsy. The authors present a detailed study of a 16-year-old boy who underwent surgery for a severe seizure disorder. This patient had dysgenesis of the right hemisphere, which was composed of a giant central frontoparietal nodular gray matter heterotopia with overlying large islands of cortical dysplasia around a displaced central fissure. Exceptional insight into the function, biochemistry, electrophysiology, and histological structure of this lesion was obtained from neurological studies that revealed complementary information: magnetic resonance (MR) imaging, [18]fluoro-2-deoxy-d-glucose positron emission tomography (PET), functional PET scanning, proton MR spectroscopic (1H-MRS) imaging, intraoperative cortical mapping and electrocorticography, in vitro electrophysiology, and immunocytochemistry. These studies demonstrated compensatory cortical reorganization and showed that large areas of heterotopia and cortical dysplasia in the central area may retain normal motor and sensory function despite strikingly altered cytoarchitectonic organization and neuronal metabolism. Such lesions necessitate appropriate functional imaging studies prior to surgery and cortical mapping to avoid creating neurological deficits. Integrated studies, such as PET, 1H-MRS imaging, cortical mapping, immunocytochemistry, and electrophysiology may provide information on the function of developmental disorders of cerebral organization.

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Mark C. Preul, Joseph Stratford, Gilles Bertrand and William Feindel

✓ Neurosurgeons are well known for being productive researchers and innovators. Few, however, have possessed the prolific ingenuity of William Cone. In 1934, he and Wilder Penfield were cofounders of the Montreal Neurological Institute where, until 1959, he filled the twin roles of neurosurgeon-in-chief and neuropathologist.

Because he did not find writing easy, many of his technical inventions and refinements remained unpublished. His numerous innovations included the extensive use of twist-drill technique for biopsy, drainage for subdural hematoma and cerebral abscess, and ventriculography. In the mid-1940's, he developed power tools driven by nitrogen that led to the modern, universally used air-driven tool systems. He had a special interest in the treatment of spinal dysfunction, for which he invented the Cone-Barton skull-traction tongs along with the Cone spinal operating table. He also devised operative procedures for vertebral fracture-dislocation and craniospinal anomalies. For the maintenance of muscle tone in the paralyzed bladder, he constructed a tidal drainage system. He introduced and popularized ventriculoperitoneal shunting techniques and carried out some of the earliest experimental trials to treat brain infections with sulphonamide and antibiotic drugs. He designed his own set of surgical suction devices, bone rongeurs, and a personal suction “air-conditioning” system for each surgeon. He had a keen early interest in intracranial tumors, and also demonstrated on monkeys how subdural mass lesions caused pupillary dilation and mesial temporal lobe damage due to cerebral compression. His work for the military during World War II on effects of altitude on brain pressure remained classified for many years. The first clipping and excision of an intracranial aneurysm is attributed to Cone.

Although Penfield was known as “the Chief,” Cone was referred to as “the Boss.” His fervent dedication to provide total care to his patients was expressed in round-the-clock vigils; he did not separate “nursing” from “surgical” care. Ultimately, Cone's driving passion for perfection led in part to his tragic death. His accomplishments, inventions, and his example as teacher and physician have become part of neurosurgery's collective legacy.

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Spinal angiolipomas

Report of three cases

Mark C. Preul, Richard Leblanc, Donatella Tampieri, Yves Robitaille and Ronald Pokrupa

✓ Spinal angiolipomas are distinct, benign lesions composed of mature lipocytes admixed with abnormal blood vessels. Three new cases of spinal angiolipoma are presented and 34 previously reported cases are analyzed. The 37 total cases (23 females and 14 males) ranged in age from 17 to 73 years (mean 43 years; median 45 years). The mean age of the female patients was older than that for the males (45.0 vs. 41.6 years; p < 0.001, Student's t-test) and most were peri- or postmenopausal. Prior to diagnosis, 97% of the patients had weakness of the lower extremities, 94% had sensory dysfunction, 84% had hyperreflexia and spasticity, 51% had sphincter dysfunction, and 41% had back pain lasting from 1 to 180 months (mean 28 months). Five (22%) of the 23 female patients were pregnant and two had exhibited significant weight gain coincident with the onset of symptoms. The angiolipomas were extradural in 35 patients and intramedullary in two; seven of the extradural lesions infiltrated the surrounding bone. The tumors extended from C-6 to L-4 and had a predilection for the midthoracic region (53% of cases). Plain radiographs were abnormal in 11 (39%) of 28 patients and in all patients with bone infiltration. Myelograms were abnormal in 97% of 32 patients and showed a complete block in 63% of patients. Computerized tomography (CT) and magnetic resonance (MR) imaging revealed the fat-density lesions in all cases studied. There was vascular enhancement in three of five cases with contrast-infused CT and in the one case with gadolinium-infused MR imaging. All patients improved following resection of the epidural lesions and internal decompression of the intramedullary lesions.

It is concluded that spinal angiolipomas predominantly affect women. They involve the thoracic (especially the midthoracic) region, and produce symptoms and signs of spinal compression and, in some cases, bone erosion and pathological fractures. Their symptomatology can be exacerbated by pregnancy and weight gain, suggesting that vascular engorgement and the presence of obesity influence their evolution. Their preponderance in older, peri-, or postmenopausal women, and their clinical exacerbation in pregnant women support a role for hormonal influence. Magnetic resonance imaging is the investigation of choice for the diagnosis of these lesions. Surgery is universally successful in relieving symptoms.

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Origins of Wilder Penfield's surgical technique

The role of the “Cushing ritual” and influences from the European experience

Mark C. Preul and William Feindel

✓ Wilder Penfield left two great legacies: the development of successful surgical treatment of epilepsy and the establishment with his colleagues of the Montreal Neurological Institute as a world-renowned medical center, “dedicated to relief of pain and suffering and to the study of neurology.” That Harvey Cushing's surgical ritual (which stemmed from the painstaking operative methods of Halsted) played a paramount role in the origins of Penfield's surgical technique is revealed by a set of notes and drawings by Penfield during repeated visits in the 1920's to Cushing's clinic at the Peter Bent Brigham Hospital.

Penfield's intellectual approach to the nervous system was derived from his studies with Sherrington, Holmes, Cajal, and Hortega. His eclectic surgical style emerged from his familiarity with the operating techniques of Halsted, Dandy, Horsley, Sargent, Cushing, Frazier, Whipple, Leriche, and Foerster. Penfield's debt to these teachers is documented in his memoirs and in an unpublished report on European neurosurgery which he sent to the Rockefeller Foundation in 1928.