As we already noted in the first volume on aneurysms, the detailed anatomy of an AVM can only be completely and definitely evaluated at microsurgical exploration and not by any imaging technique. Although superselective angiography provides essential information regarding the composition of an AVM, we would like to have even more sophisticated angiographic techniques for even more precise study of the vascular composition and the hemodynamics of the AVM nidus and its compartments; this is already practiced daily by interventional neuroradiologists for vascular lesions of the skull base as well as head and neck. Professor Valavanis of Zurich, who performed all pre- and postoperative neuroradiological procedures since 1978, has been invited to provide the chapter on the neuroradiological evaluation of cerebral vascular malformations, also summarizing the relative role of CT, MRI and angiography. We refused to perform invasive studies to assess the hemodynamics of AVMs in our patients. However, we routinely applied non-invasive Doppler-ultrasound pre- and postoperatively. Professor Keller of Zurich, has contributed a separate chapter on his Doppler-ultrasound technique, summarizing the principles and the results of this method.
Modern neurosurgery is inherently dependant on the advances in neuroanesthetic techniques. During the last 20 years, five groups of anesthesiologists were involved in our daily work. The results achieved in the surgical management of intracranial AVMs were also possible thanks to the great effort of our neuroanesthesiologists, especially Drs. M. Curcic and Dr. M. Kis, who have been responsible for neuroanesthesia during the last 10 years.
In Volume III B of this series, the surgical techniques and results as well as the neuroanesthetic technique will be presented in detail.
1 History
A Short History of the Diagnosis and Treatment of Cerebral AVMs
As attested by F. Henschen (1955) angiomatous malformations and tumors have been, since Virchow’s time, a “problem child” of pathologists. Hamby (1958) defined the main problems posed in understanding the pathology of these lesions and his statements are valid even today:
“The origin and anatomy of the cerebral angiomas has frustrated pathologists over the years as much as their treatment has baffled surgeons. An extensive literature has developed, replete with picturesque nomenclature based upon attempts to describe the appearance of lesions seen at the operative table or at necropsy. The surgical descriptions are not entirely basic nor accurate because the bulk of the lesion is largely submerged under the cortex and hence invisible to the examiner. The pathologic descriptions have been faulty because of deflation of the lesion at the time of examination by lack of the expansile blood stream that characterizes them in life. Also confusing the picture of the dead lesion are the alterations produced in the component vessels by blood under arterial pressure, which dilates veins and “arterializes” them to withstand the added stress. Vascular resistance being lowered by the shunt, arteries dilate to carry more blood under less than usual pressure, and lose some of their usual characteristics.”
However, the introduction of cerebral angiography (Moniz 1927) together with the continuing improvements in the quality of angiograms and the remarkable developments in vascular catheterization techniques (Seldinger 1953, Djindjian 1962) has opened up new dimensions in the study of the morphological and hemodynamic aspects of AVMs.
This short historical review may help to understand how we have arrived at the present day interpretations of AVM pathology and development and how modes of treatment have evolved.
Pre-17th Century
Descriptions of vascular malformations of the skin and other visible organs such as eye, lips and ear with occasional comments about their often ugly appearance and the difficulty or impossibility of treatment may be seen in some of the earliest recorded historical manuscripts.
The Papyrus Ebers (ca. 1500 BC) contained descriptions of hemorrhoids, skin tumors, hydroceles, varicose veins and aneurysms. Kharadly (1956) showed that hernias and aneurysms were operated upon even in those times but not AVMs. The warning, “You must keep your hands off – Noli me tangere” is stated in the relevant chapter.
Virchow cited prominent physicians like Hippokrates, Galen, Celsus, Aetius, Avicenna, and Vidus Vidius, who were dealing with the diagnosis and treatment of different types of external vascular malformations. Von Bramann (1886) showed that Galen and Delia Groce knew of varicose pulsating swellings and took them to be simple arterial aneurysms. Osier (1915) noted that references to vascular malformations are to be found in the works of Antyllus (2nd Century) and Abulcasis (10th Century).
17th–19th Century
The great breakthroughs in the understanding of the systemic circulation and of the cerebral circulation were made by Harvey (1628) and Willis (1664) respectively.
William Hunter (1718–1783)
(By kind permission of the President and Council of the Royal College of Surgeons of England)
John Hunter (1728–1793)
The work of Harvey and Willis was subsequently complemented by the discovery of the capillary system by Malpighi (1661) and this paved the way for modern theories regarding the evolution and pathology of AVMs.
In the following century (1757) William Hunter was able to identify the clinical characteristics and some hemodynamic aspects of extracranial AVMs. In “Observations on arteriovenous malformation, London Medical Observations and Enquiries, 1762” he wrote: “Vascular malformations of the extremities are caused by an abnormal communication between arteries and veins.” Enthusiastic phlebotomists of that period prepared two perfect examples of arteriovenous aneurysm for W. Hunter, which he was quick to recognize (cit. Dandy 1928); at the point of communication between the artery and the vein, he recognized a loud hissing bruit and a strong tremulous thrill: large tortuous sacs were seen to pulsate; the brachial artery was greatly enlarged and serpentine cephalad to the arteriovenous fistula, but distal to it, the artery became smaller than on the other side. He was able to reduce the size of the vein, stop their pulsation and eliminate both the bruit and the thrill by pressing on a localized spot, which he recognized to be the opening between the artery and vein. It was William Hunter who first suggested the term “anastomosis” to denote the union of the two vessels, whereas the term “collateral” was introduced by his younger brother John Hunter who also ligated the femoral artery in a case with popliteal aneurysm and proved the efficiency of the collateral arterial system.
The broad scientific approach concerning the nature of these impressive aberrations began with pathologists and surgeons 200 years ago who described them as “erectile tumors” and swellings of the skin and organs. The advent of medical journals enabled the scientists to publish their observations.
After 1850 the number of publications concerning these erectile tumors increased rapidly. Between the time of William Hunter (1762) and Sonntag (1919), 65 such publications are to be found: Plenck (1776), Bell (1796), Cruveilhier (1816), Meckel (1818), Dupuytren (1834), Vidal (1846), Rokitansky (1846), Virchow (1851), Gerdy (1852), Schuh (1853, 1866), Busch (1854), Luschka (1854), Esmarch (1854), Lebert (1857), Bennet (1854), and Alibert (1871). More detailed information regarding these papers may be found in the works of Heine (1869), Weber (1869), Körte (1880) and Heineke (1882). Pathological classification based upon varied anatomical descriptions was already becoming clumsy and confusing. By 1894 Wagner had collected from the current literature 24 different nomenclatures. In parallel with changing pathological concepts, the surgery of extracranial AVMs was undergoing