Pediatric Regional Anesthesia

BernardJ. Dalens

• Publisher: Routledge
• Year: 2019
• Print ISBN: 9780849356292
• eBook ISBN: 9781351425599
• Topic: Medicine
• Subtopic: Anesthesiology & Pain Management

This book provides a precise description of safe and reliable procedures for regional anesthesia in children. It covers the advantages and disadvantages, specific features related to the pediatric range of ages, and the practical importance of the described procedures. Written in two main parts, emphasis is placed on scientific basis and technical approach. It includes both anatomical and psychological aspects of pain, as well as detailed viewpoints of parents, children, surgeons, and anesthetists. This book is a must for all anesthesiologists and will be particularly useful to students of medicine and anesthesiology and nurses working with intensive care units.

Part One

GENERAL CONSIDERATIONS

SECTION I: ANATOMICAL AND DEVELOPMENTAL DATA

Bernard J. Dalens and Guy N. Vanneuville

TABLE OF CONTENTS

Chapter 1. General Organization of the Nervous System

Chapter 2. Embryology of the Spinal Cord, Peripheral Nerves, and Vertebrae

I. Early Embryonic Events

II. The Differentiation of the Spinal Roots and Ganglia

III. The Formation of Nerve Plexuses and Sympathetic Tracts

IV. The Differentiation of Vertebrae

V. The Fetal Period

Chapter 3. The Spinal Cord and the Spinal Canal

I. Gross Anatomy

II. Internal Structure of the Spinal Cord

A. The Gray Matter

1. General Arrangement

2. The Ventral Horns

3. The Dorsal Horns

4. Cytoarchitectural Lamination

B. The White Matter

1. Gross Anatomy

2. Long Descending Tracts

a. The Corticospinal System

b. Other Long Descending Tracts

3. Long Ascending Tracts

a. Fasciculi Gracilis and Cuneatus

b. Spinothalamic Tracts

c. Spinocerebellar Tracts

d. Other Long Ascending Pathways

4. Short Ascending and Descending Tracts

a. Fasciculi Proprii

b. Fasciculi Interfascicularis and Septomarginalis

III. The Spinal Roots and Ganglia

A. Ventral (or Anterior) Roots

B. Dorsal (or Posterior) Roots

C. Spinal Ganglia

IV. The Spinal Nerves, Rami, and Dermatones

A. Meningeal Rami

B. Dorsal (Posterior) Rami

C. Ventral (Anterior) Rami

D. Rami Communicantes

V. The Spinal Canal

A. General Characteristics of a Vertebra

B. Intervertebral Disks

C. Constitution of the Spinal Canal

D. Spaces of the Spinal Canal

VI. Blood Supply to the Spinal Cord

A. Arterial Supply

1. Blood Supply from Vertebral Arteries

2. Blood Supply from Segmental Arteries

B. Venous Drainage

VII. Regional Variations

A. Morphology of Vertebrae

B. Spinal Columns and Spinal Roots

C. Variations in Blood Supply

Chapter 4. The Peripheral Nerves

I. Peripheral Nerve Fibers

A. Myelinated Fibers

B. Unmyelinated Fibers

II. Structure of the Peripheral Nerves

Chapter 5. The Autonomic Nervous System

I. General Organization

II. The Parasympathetic System

A. Central Autonomic Pathways

B. Peripheral Autonomic Pathways

1. Efferent Pathways

2. Afferent Pathways

III. The Sympathetic System

A. Central Autonomic Pathways

B. Peripheral Autonomic Pathways

1. Efferent Pathways

2. Afferent Pathways

References

Chapter 1

GENERAL ORGANIZATION OF THE NERVOUS SYSTEM

The Hand that made us is divine.

(The Spectator, 474)

Joseph Addison

(1672—1719)

The nervous system is made up of highly differentiated tissues, the function of which is the transmission of information. In lower animals, such a system does not exist and each stimulation of sensory cells by environmental factors is propagated to muscle cells via cytoplasmic expansions. A similar organization can still be found in olfactory cells in humans, but in the higher animals a nerve cell usually mediates the propagation of excitatory stimuli applied to other nerve or muscle cells. Thus a system of nerves is created and it is called the autonomic nervous system. This system is subdivided into two antagonist parts: the sympathetic (thoracolumbar) and parasympathetic (craniosacral) nervous systems. The combination and intermingling of sympathetic and parasympathetic fibers allow precise and automatic (involuntary) regulation of vital functions.

With vertebrates, a further increase in the differentiation of nerve cells gives rise to a system specifically devoted to communication with the surroundings. This system transmits bidirectional information, allowing peripheral stimuli from sensory cells to reach the organizing center, the brain, where the information can be integrated. This system also conveys efferent impulses, which transfer orders from the brain or spinal cord to peripheral muscle cells, with subsequent modifications as required to adjust to the environment. The nervous system is divided into two subsystems:

1. The central nervous system, including the cortex, brain stem, cerebellum, and spinal cord

2. The peripheral nervous system, consisting of the spinal roots, ganglia and nerves, and the peripheral nerves

This classification is founded on embryonic events. From the point of view of the anesthesiologist, it would be simpler to classify nervous components as:

1. An organizing center, the brain, which is the principal target of general anesthetics (generally speaking)

2. Conduction (motor and sensory) pathways, including the spinal cord, the roots, and the peripheral nerves, which are the main target of local anesthetics

Chapter 2

EMBRYOLOGY OF THE SPINAL CORD, PERIPHERAL NERVES, AND VERTEBRAE

The development of the spinal cord and vertebrae is a complex phenomenon.^{1, 2, 3, 4, 5, 6, 7} The scheme described by O’Rahilly and Meyer⁸ for the developmental stages of human embryos will be used in this chapter.

I. EARLY EMBRYONIC EVENTS

In stage 6 (two weeks of gestation), the germ-disc is didermic and consists of two layers of cells, the entoderm (ventrally) and the ectoderm (dorsally) which together constitute the embryonic disc (Figure 1.1). The first rudiments of the axial skeleton are mesodermal cells, which can be recognized in stage 7 (0.5- to 1-mm embryos, 16 to 17 d). These cells appear dorsally and differentiate as the prechordal plate (Figure 1.2). In stage 8 (1- to 1.5-mm embryos, 17 to 19 d), the notochord and dorsal ectodermal structures differentiate. As they develop, they set up the neural plate rostral to both the primitive streak and Hensen’s node (Figure 1.3).⁹

In stage 9 (1.5- to 2-mm embryos, 19 to 20 d), the neural plate is curled (Figure 1.4). The embryonic disc elongates and the primitive streak and Hensen’s node appear to be carried caudad, since the cephalic area grows more rapidly. The embryo changes its shape, becoming first oval, then pear shaped. At this stage, the neural groove is in close contact with the notochord. Mesenchymatous cells of both sides of the notochord (paraxial mesoderm) show intense mitotic activity and differentiate as paired blocks of cells, the somites. This fundamental aspect of metamerism of the body does not occur in the paraxial mesoderm of the cephalic area.

In stage 10 (on and after the 20th day), the neural plate becomes a cylinder, the neural tube, by the fusing of its lateral boundaries, the neural folds, in the region of the fourth somite (Figure 1.5). The two extremities of the neural tube, the anterior (cranial) and posterior (caudal) neuropores, are free. At this stage, alkaline phosphatase activity can be detected.⁹ Some cell islets, issuing from the lateral edges of the neural plate, shift downwards through the mesodermal mantle so as to create masses lateral to the neural tube. These masses are known as the neural crests (Figure 1.6).

The next major developmental feature is the differentiation of somites in three distinguishable areas (Figure 1.7):

1. Two external structures: medially the myotome, and laterally the dermatome (also termed dorsolateral lamella or cutis plate)

2. One internal cell mass, the sclerotome, in which the density of nuclei gradually increases, rostral to caudal

Cell islets from sclerotomes (Figures 1.7 and 1.8) extend (1) ventrally and medially, surroundi...

Table of contents

• Cover
• Title Page
• Copyright Page
• Preface
• The Editor
• Contributors
• Acknowledgments
• Dedication
• Table of Contents
• Introduction
• PART ONE: GENERAL CONSIDERATIONS
• PART TWO: TECHNICAL CONSIDERATIONS
• Index