Surgery of the Human Cerebrum Part II.pdf

EDITOR’S LETTER

S URGERY OF THE H UMAN C EREBRUM II:

T HE B ROADEST C ANVAS

rguably the broadest canvas for application of

the technical advances in the biological and

hard sciences is the human cerebrum.

Indeed, these opportunities for application have

been realized in areas that have been approached in

P ART II of this three part series.

Advances in imaging, technical miniaturization,

and the computer have played an essential role in

changing our approaches to a wide spectrum of

disorders affecting the brain. Physical and biological

capabilities have offered new apertures to the

treatment of epilepsies, movement disorders, and

other functional problems. The amalgam of the

computer, imaging, and the sophisticated control of

high energy forms has offered a neurosurgical tool

called stereotactic radiosurgery, which already has

evolved through a number of phases of

advancement becoming an essential

feature of every truly modern

neurosurgical practice.

Endoscopy, through technical

improvement in application of physical

principles of prism physics and light

gathering capacity, coupled with

progressive miniaturization and fiber

optics have revolutionized ideas related

to intraventricular access and the

management of hydrocephalus as well as other

technical challenges.

Technical advances in valve construction and

design along with imaging capabilities have changed

elements of approaches to the composite of

hydrocephalic syndromes and etiologies.

A combination of these capabilities has modified

and enhanced our views concerning the

management of cerebral infections and infestations.

In short, during a single generation, technical

management capabilities and strategies have

undergone immense metamorphoses!

For P ART II OF S URGERY OF THE H UMAN

C EREBRUM , this remarkable evolution and what

might be termed the current "state of the art" is

discussed by a number of esteemed individuals and

coauthors:

1) Epilepsy - Johannes Schramm

2) Infections and Infestations - Walter A. Hall

3) Endoscopy - Paolo Cappabianca

4) Pediatric Hydrocephalus - James M. Drake

5) Adult Hydrocephalus - Marvin Bergsneider

6) Stereotactic Radiosurgery - Douglas Kondziolka

7) Movement Disorders - Ali R. Rezai

These papers are augmented by selected relevant

recent archival manuscripts and individual attendant

bibliographies from the Journal's publications over

the past decade.

No doubt, in considering a

retrospective view in the history of

medicine and especially neurological

surgery, this documentation of

current capability and strategy is

phenomenal - particularly considering

the developmental time frame!

This material and that presented in

P ART I of this monumental supplement

will be augmented by an additional 30th

Anniversary offering with focus on the topics of

Psycho-affective Disorders and Pain (Giovanni Broggi),

3D Microsurgical and Tractographic Anatomy of the

White Matter of the Human Brain (Albert Rhoton, Jr.),

Intraventricular Tumors (M. Gazi Yasargil), Extra Axial

Lesions (Peter Black), Basal Lesions (Madjid Samii),

Giant Aneurysms (Robert Spetzler), Revascularization

(Laligam Sekhar), Endovascular Techniques (L. Nelson

Hopkins), and Advanced Methodologies (Michael

Apuzzo) in P ART III - the final component of the

volume.

Michael L.J. Apuzzo

Los Angeles, California

Neurosurgery 62 [SHC Suppl 2]:SHC459, 2008

DOI: 10.1227/01.NEU.0000297092.02228.55

Number 8, 1949 by Jackson Pollock. Collection Neuberger

Museum of Art, Purchase College, State University of New

York, gift of Roy R. Neuberger, Jim Frank, photographer.

VOLUME 62 | NUMBER 2 | FEBRUARY 2008 SUPPLEMENT | SHC459

EPILEPSY

T HE S URGERY OF E PILEPSY

Johannes Schramm, M.D.

Department of Neurosurgery,

University of Bonn Medical Center,

Bonn, Germany

THE IDEA OF surgical treatment for epilepsy is not new. However, widespread use and

general acceptance of this treatment has only been achieved during the past three

decades. A crucial step in this direction was the development of video electroen-

cephalographic monitoring. Improvements in imaging resulted in an increased ability

for preoperative identiﬁcation of intracerebral and potentially epileptogenic lesions.

High resolution magnetic resonance imaging plays a major role in structural and func-

tional imaging; other functional imaging techniques (e.g., positron emission tomogra-

phy and single-photon emission computed tomography) provide complementary data

and, together with corresponding electroencephalographic ﬁndings, result in a hypoth-

esis of the epileptogenic lesion, epileptogenic zone, and the functional deﬁcit zone.

The development of microneurosurgical techniques was a prerequisite for the general

acceptance of elective intracranial surgery. New less invasive and safer resection tech-

niques have been developed, and new palliative and augmentative techniques have

been introduced. Today, epilepsy surgery is more effective and conveys a better seizure

control rate. It has become safer and less invasive, with lower morbidity and mortal-

ity rates. This article summarizes the various developments of the past three decades

and describes the present tools for presurgical evaluation and surgical strategy, as well

as ideas and future perspectives for epilepsy surgery.

KEY WORDS: Electroencephalographic monitoring, Epilepsy, Epileptogenic lesion, Seizure control, Surgery

Hans Clusmann, M.D.

Department of Neurosurgery,

University of Bonn Medical Center,

Bonn, Germany

Reprint requests:

Hans Clusmann, M.D.,

Department of Neurosurgery,

University of Bonn Medical Center,

Sigmund Freud Straße 25,

52105 Bonn, Germany.

Email: hans.clusmann@ukb.uni-bonn.de

Received, May 4, 2007.

Accepted, October 25, 2007.

Neurosurgery 62[SHC Suppl 2]:SHC463–SHC481, 2008

DOI: 10.1227/01.NEU.0000297106.65002.1F

CONCEPTS FOR EPILEPSY SURGERY

were ﬁrst implanted by Jean Bancaud (7) and Jean Talairach

(176) in France. The ﬁrst chronic depth electrode recording and

EEG telemetry were realized by Paul H. Crandall (42, 107).

This has been the setup for the development of epilepsy sur-

gery in the last 30 years.

(1857–1916) in London were the ﬁrst to localize and

remove epileptogenic lesions, as identiﬁed by their

symptomatogenic zone, according to the pioneering work of

John Hughlings Jackson (1835–1911). Additional developments

were made in Germany by the neurosurgeons Fedor Krause

(1857–1937) and Otfried Foerster (1873–1941). Human scalp

electroencephalography (EEG) was ﬁrst described in 1929 by

Hans Berger (11), who revolutionized epilepsy diagnosis

within 10 years with a hypothesis on the irritative and ictal

onset zones (152). Herbert Jasper (1941) described the EEG

characteristics of psychomotor seizures. This knowledge con-

tributed to the ﬁrst temporal lobe resection for epilepsy in 1936

by Wilder Penfield. The first purely EEG-directed temporal

lobe resections were performed in Boston in 1947 by Percival

Bailey (1892–1973) with the neurophysiologist Frederick Gibbs

(1903–1992). Electroclinical monitoring of patients with

epilepsy, including the institution of simultaneous clinical and

EEG observations and chronic intracranial EEG recordings, was

established in the 1940s in a few specialized centers, ﬁrst in the

Montreal Neurological Institute. Stereotactic depth electrodes

Developments since the 1970s

With the advent of positron emission tomography (PET) in

the late 1970s, and even more with magnetic resonance imag-

ing (MRI) in the 1980s, worldwide interest in epilepsy surgery

increased, enabled by the preoperative identiﬁcation of intrac-

erebral and, potentially, epileptogenic lesions (21, 22, 41, 79,

99). Thus, new imaging methods increasingly eliminated the

uncertainty among preoperatively known clinical syndromes,

preoperative EEGs, and the intraoperative ﬁndings, as well as

the postoperative histological results. The more lesion-directed

approach (MRI) and the complementary information provided

by functional imaging techniques (PET and single-photon

emission computed tomography [SPECT]) resulted in identiﬁ-

cation of epileptogenic lesions and functional deficit zones

(152). Developments were supported further by the parallel

advent of effective digital video techniques and data storage.

During the past 30 years, four developments have occurred

in parallel, albeit not in perfect synchrony: 1) the advent of

N EUROSURGERY

VOLUME 62 | NUMBER 2 | FEBRUARY 2008 SUPPLEMENT | SHC463

Historical Development before the 1970s

W illiam MacEwen (1848–1924) and Victor Horsley

S CHRAMM AND C LUSMANN

microneurosurgery, 2) the associated improvements in outcome

leading to a general acceptance of neurosurgery performed as

elective surgery, 3) development of new concepts of areas

involved or associated with epileptogenicity, and 4) simultane-

ous surface and depth recording with stereo-EEG providing

more detailed facts about the distribution and spread of epilep-

tic activity (7, 42, 177, 194, 205).

Recent Evolution and Progress: New Concepts

As mentioned previously, former work resulted in a theory

of different zones involved in the epilepsies. Despite some def-

inition differences, these concepts turned out to be important

because they are the fundaments of applying multiple diagnos-

tic means to approach the “epileptogenic zone” (134, 152, 194).

Six cortical zones that are considered at present in the presur-

gical evaluation of candidates for epilepsy surgery are: the

symptomatogenic zone, the irritative zone, the seizure-onset

zone, the epileptogenic lesion, the epileptogenic zone, and the

eloquent cortex. Rosenow and Lüders (152) reviewed the step-

wise historical evolution of these different zones. Different

diagnostic techniques are used in the deﬁnition of these corti-

cal zones such as video-EEG monitoring, MRI, ictal SPECT,

and PET. Established diagnostic tests have to be set apart from

procedures that should still be regarded as “experimental” such

as magnetoencephalography (MEG), dipole-source localization,

and spike-triggered functional MRI, although improvements in

these noninvasive techniques may lead to a more direct deﬁni-

tion of the epileptogenic zone (152).

The epileptogenic zone is deﬁned as a cortical area that is

inevitably necessary for the generation of clinical epileptic

seizures (152). This concept can only be proven by a circum-

scribed cortical resection leading to seizure freedom. In clinical

practice, the concept of an epileptogenic zone is a multidimen-

sional localization hypothesis, applying all available clinical

and technical diagnostic tools, however, never gaining absolute

certainty (108).

New Diagnostic Techniques

In the ﬁeld of presurgical evaluation, which is thought to be

most crucial for failure or success after epilepsy surgery, intro-

duction of MRI played a major role. However, in its early days,

MRI was directed exclusively to the identiﬁcation of morpho-

logical changes, i.e., the identification of a lesion, which is

known as an “epileptogenic lesion.” This was a tremendous

step forward, because it enabled noninvasive screening of the

brain for structural abnormalities with a sensitivity that

increased over the years. It is obvious that not everything

abnormal that we see has to do with the patient’s epilepsy. It is

standard practice to identify mesial temporal sclerosis on tem-

poral angulated MRI scans, especially in the coronal plane,

even without the application of more sophisticated algorithms

like magnetic resonance relaxometry or hippocampal volume-

try ( Fig. 1 ) (181). Moreover, new and speciﬁc information can be

derived on the nature of cortical dysplasias. Whereas even 10

years ago most types of malformations of cortical development

remained speculative using MRI, with high numbers of misin-

FIGURE 1. A , upper panel , T2-weighted

images acquired in the mid-1990s in stan-

dard angulation showing some hippocam-

pal atrophy on the left side; middle

panel , ﬂuid-attenuated inversion recov-

ery (FLAIR) and T2-weighted images of

the same patient obtained some time later

with temporal angulation suggesting not

only atrophy, but also hippocampal sclero-

sis; lower panel , recent FLAIR and T2-

weighted images of other patients in

whom even mild hippocampal signal

changes can be detected, even in the ab-

sence of severe hippocampal atrophy. B ,

coronal magnetic resonance imaging (MRI) scans were acquired in tempo-

ral angulation, illustrating the present standard of detecting mesial tem-

poral sclerosis with a 3-T MRI scanner. C , schematic drawing showing

standard ( dotted line ) versus temporal ( straight line ) MRI angulation.

SHC464 | VOLUME 62 | NUMBER 2 | FEBRUARY 2008 SUPPLEMENT

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