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Mark C. Preul

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Percutaneous trigeminal ganglion compression for trigeminal neuralgia

Experience in 22 patients and review of the literature

Jeffrey A. Brown and Mark C. Preul

✓ Between 1983 and 1988, a percutaneous trigeminal ganglion compression (PTGC) procedure for trigeminal neuralgia was performed on 22 patients. All patients were initially relieved of their pain. There were three recurrences (14%); two of these patients underwent a second PTGC procedure and one a partial trigeminal nerve root section. Follow-up examination 3 to 53 months after the procedure showed that all patients were free of pain. Morbidity included persistent minor hypesthesia in five patients, persistent minor dysesthesias in three, persistent minor weakness in three, aseptic meningitis in one, transient sixth nerve palsy in one, and transient otalgia in three. None of the patients had either anesthesia dolorosa or an absent corneal reflex.

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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 Penfield's debt to these teachers is documented in his memoirs and in an unpublished report on European neurosurgery which he sent to the Rockefeller Foundation in 1928.

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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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Robert W. Ryan, Robert F. Spetzler, and Mark C. Preul

In this historical review the authors examine the important developments that have led to the availability of laser energy to neurosurgeons as a unique and sometimes invaluable tool. They review the physical science behind the function of lasers, as well as how and when various lasers based on different lasing mediums were discovered. They also follow the close association between advances in laser technology and their application in biomedicine, from early laboratory experiments to the first clinical experiences. Because opinions on the appropriate role of lasers in neurosurgery vary widely, the historical basis for some of these views is explored. Initial enthusiasm for a technology that appears to have innate advantages for safe resections has often given way to the strict limitations and demands of the neurosurgical operating theater. However, numerous creative solutions to improve laser delivery, power, safety, and ergonomics demonstrate the important role that technological advances in related scientific fields continue to offer neurosurgery. Benefiting from the most recent developments in materials science, current CO2 laser delivery systems provide a useful addition to the neurosurgical armamentarium when applied in the correct circumstances and reflect the important historical advances that come about from the interplay between neurosurgery and technology.

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Ali Tayebi Meybodi, Sirin Gandhi, Mark C. Preul, and Michael T. Lawton


Exposure of the vertebral artery (VA) between C-1 and C-2 vertebrae (atlantoaxial VA) may be necessary in a variety of pathologies of the craniovertebral junction. Current methods to expose this segment of the VA entail sharp dissection of muscles close to the internal jugular vein and the spinal accessory nerve. The present study assesses the technique of exposing the atlantoaxial VA through a newly defined muscular triangle at the craniovertebral junction.


Five cadaveric heads were prepared for surgical simulation in prone position, turned 30°–45° toward the side of exposure. The atlantoaxial VA was exposed through the subatlantic triangle after reflecting the sternocleidomastoid and splenius capitis muscles inferiorly. The subatlantic triangle was formed by 3 groups of muscles: 1) the levator scapulae and splenius cervicis muscles inferiorly and laterally, 2) the longissimus capitis muscle inferiorly and medially, and 3) the inferior oblique capitis superiorly. The lengths of the VA exposed through the triangle before and after unroofing the C-2 transverse foramen were measured.


The subatlantic triangle consistently provided access to the whole length of atlantoaxial VA. The average length of the VA exposed via the subatlantic triangle was 19.5 mm. This average increased to 31.5 mm after the VA was released at the C-2 transverse foramen.


The subatlantic triangle provides a simple and straightforward pathway to expose the atlantoaxial VA. The proposed method may be useful during posterior approaches to the craniovertebral junction should early exposure and control of the atlantoaxial VA become necessary.