Neurology in Our Midst: A Primer to Neuroanatomy and Clinical Neurology

By Dr. Amado M. San Luis

The author noted, after more than 35 years of teaching, that many medical, nursing and physical therapy students, as well as, generalists, feared or avoided neurology and neurological patients.

Neurology in Our Midst is a form of interventional neurology book that addresses this problem. The writing style deviates from the usual medical books. The content simplifies and avoids obfuscation of the language of neurology. It emphasizes understanding of how the central nervous system (CNS) controls our daily activities and if injured or afflicted by diseases, how they manifest. Bedside examinations, to unmask the aberrant functions, are detailed and the abnormalities are explained for the purpose of localization. CNS anatomic structures are dissected into chapters and paired with clinical examples and neuroanatomic correlations. The “Waterloo” of neurology is the understanding and evaluation of unconscious patients, so, the book addressed this difficulty. The cerebrospinal fluid circulation and cerebrovascular neuroanatomy are discussed and correlated with hydrocephalus and stroke.

Neuroanatomy and clinical neurology lectures will be more interesting and meaningful if one reads the entire book before attending them.

• Language: English
• Publisher: Xlibris US
• Release date: May 10, 2019
• ISBN: 9781984569592

Dr. Amado M. San Luis

Dr. Amado San Luis completed his neurology training at the University of the East Ramon Magsaysay Memorial Medical Center, a premiere medical institution in the Philippines, where he went on to practice and teach neurology for 35 years. Dr. San Luis did not only teach medical students, but even nurses, physical therapists, patients afflicted with neurological diseases and their relatives. A talented artist who believes that everyone can and should understand the fundamentals of neurology, Dr. San Luis once sketched the brain to help her 12-year old daughter understand why she has chronic migraine. While raising his eight kids, Dr. San Luis completed his post-graduate training in Neurology Research and Neurophysiology at the Kyushu University Neurological Institute, Fukuoka, Japan and Masters in Public Health at UERM. He also served as President of the Philippine Neurological Association in 1996 and the Asian and Oceanian Association of Neurology from 2000 to 2008. In 2015, he established the Center for Neurological Sciences at the Quirino Memorial Medical Center, Philippines, to serve indigent patients, train neurology residents and nurses, and advance research in the field of neurology.

Book preview

NEUROLOGY in

OUR MIDST

A Primer to Neuroanatomy and

Clinical Neurology

Dr. Amado M. San Luis

Copyright © 2019 by Dr. Amado M. San Luis.

Library of Congress Control Number:      2018914207

ISBN:            Hardcover                             978-1-9845-6960-8

           Softcover                              978-1-9845-6961-5

             eBook                                   978-1-9845-6959-2

All rights reserved. No part of this book may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without permission in writing from the copyright owner.

Any people depicted in stock imagery provided by Getty Images are models, and such images are being used for illustrative purposes only.

Certain stock imagery © Getty Images.

About the Cover

Title: HUMANSCAPE in acrylic on canvas. It speaks of the body’s (humanscape’s) link with reality—how it is perceived and reacted to, how our everyday responses (individually or socially) are affected or shaped by sensitive neural links.

International Visual Artist (Sculptor, Painter, Performance Art): Sam Penaso, Guindulman,Bohol, Philippines. Had 26 solo exhibits: Japan, Austria, Germany, Singapore, New York & Abu Dhabi. Recepient of multiple international grants and international awards.

e-mail: [e-mail]

website:www.facebook.com/sampenaso

www.instagram.com/sampenaso

Tel: [phone] or 09989989899

About the Illustrations

Drawings: by the author

Digital Conversion: Ryan D. Abainza

facebook.com/ryanabainza

[e-mail]

Rev. date: 05/08/2019

Xlibris

1-888-795-4274

www.Xlibris.com

[e-mail]

551799

CONTENTS

Dedication

Acknowledgments

Foreword

Preface

Introduction

Anatomic Orientation

Chapter I

The Physiology or Mechanism of Neural Transmission

Chapter II

General Anatomy of the Central Nervous System

Chapter III

The Descending Motor or Pyramidal Tract System

Chapter IV

The Nociceptive Pain and Associated Spinothalamic Tracts

Chapter V

The Other Ascending Sensory Fibers

Chapter VI

The Cranial Nerves

Chapter VI-A

Cranial Nerve I- Olfactory Nerve

(Function: Sense of Smell)

Chapter VI-B

Cranial Nerve II- Optic Nerve

(Function: Vision/Seeing)

Chapter VI-C

Cranial Nerve III- Oculomotor Nerve,

Cranial Nerve IV- Trochlear Nerve,

Cranial Nerve VI-Abducens Nerve

(Functions: Pupillary Constriction, Eye Opening, and Eye Movements)

Chapter VI-D

Cranial Nerve V- Trigeminal Nerve

(Functions: Face Sensation and Mastication)

Functional Anatomy of CN V Trigeminal Nerve Sensory Branches

Functional Anatomy of the Muscles of Mastication

Chapter VI-E

Cranial Nerve VII- Facial Nerve

(Functions: Facial Muscles of Expression, Taste, Eye Closure, Lacrimation, Salivation, Sound Modulation)

The Facial Motor Nerve

The Nervus Intermedius

Chapter VI-F

Cranial Nerve VIII- Vestibulocochlear Nerve

(Functions: Hearing and Balance)

The Cochlear Nerve.

The Vestibular Nerve.

Chapter VI-G

Cranial Nerve IX- Glossopharyngeal Nerve

(Functions: Taste, Salivation, Baroreflex, Swallowing, Ear & Palatal Sensation)

Glossopharyngeal Nerve-Parasympathetic Nerve to the Parotid Gland

Glossopharyngeal Nerve’s Role in Swallowing

Glossopharyngeal Nerve for Taste

Pain, temperature, and touch sensation of CN IX

Chapter VI-H

Cranial Nerve X- Vagal Nerve

(Functions: Taste, Salivation, Carotid Sinus Reflex, Hering-Breuer, Visceral Organ Control, Swallowing, Phonation, External Canal Sensation)

CN X Vagus Nerve-afferent fibers

CN X. Vagus Nerve-efferent Arm

CN X. Vagus Nerve Autonomic Reflex arms

Chapter VI-I

Cranial Nerve XI- Accessory Nerve

(Swallowing and Head Movement)

Chapter VI-J

Cranial Nerve XII- Hypoglossal Nerve

(Functions: Swallowing and Sound Formation/Phonation)

Chapter VII

The Spinal Cord and Peripheral Nerves

(Functions: Sensation, Motor Strength, Reflexes, Autonomics)

The Topography of the Spinal Cord

The Backbones

The Spinal cord

Descending Fibers of the Spinal Cord

Other Descending Fibers of the Spinal Cord

Ascending Fibers of the Spinal Cord

Other ascending fibers of the spinal cord

Autonomic Nervous System of the Spinal Cord

The Topography of Peripheral Nervous System

The Motor Component of the Peripheral Nerves.

The Sensory Component of the Peripheral Nerves.

The Autonomic Nervous System

Anatomy of the Autonomic Nervous System

Parasympathetic Nervous System (PSNS)

Sympathetic Nervous System (SNS)

Chapter VIII

The Cerebellum

(Functions: Balance, Voluntary Muscle Coordination, Visio-vestibular-spatial-proprioceptive Coordination, Cognition and Affect)

Chapter IX

Basal Ganglia

(Functions: Learning and Modulating Programmed Motor Acts)

Chapter X

The Cerebral Cortex

(Functions: Memory, Learning, Language, Cognition, and Emotion)

Chapter XI

The Functional Anatomy of Sleep and Consciousness

Chapter XII

Cerebrospinal Fluid Circulation

Chapter XIII

Cerebral and Spinal Blood Circulation

The Heart.

The Branches of the Aortic Arch (Fig. 55).

The Posterior Circulation (Table VI).

The Anterior Circulation

Special Clinical Correlates for Stroke Recognition:

Spinal Cord Blood Supply

The Venous Drainage of the CNS

Summary

Bibliography

DEDICATION

To my lovely wife, Cynthia, mother to our eight beautiful children, astute pediatrician, palliative care expert, caring doctor and nurse, excellent teacher, a superhuman…my inspiration.

NEUROLOGY IN OUR MIDST

(A Primer to Neuroanatomy and Clinical Neurology)

ACKNOWLEDGMENTS

Translating and condensing into a book ones long experience in teaching neurology to medical students, nurses and physical therapists is an arduous task made more difficult by the need to address the fears and disinterest of the future health care providers. Dr. Romeo A. Divinagracia, President of UERMMMCI, challenged me to pursue writing a book about neurology. I am grateful for that dare and for providing the milieu to pursue the project. I extend this gratefulness to Dr. Alfaretta Tan-Reyes, Dean of the College of Medicine who provided valuable suggestions and constant reminding of the importance of the book. My special thanks to the Department of Clinical Neurosciences Faculty Staff who freed me from teaching assignments and other tasks that allowed me to research and write. I am sincerely appreciative for the sabbatical leave granted by my alma mater, UERMMMCI, College of Medicine.

The thoughts written in this book are not mine alone but from a thirty-five-year conglomeration of informations shared by various persons who are worthy of my utmost gratitude. Dr. Joven Cuanang, after arriving from his neurology residency at Harvard Medical School- Massachusetts General Hospital, invited me in 1977 to be a pioneer resident in Adult Neurology at UERMMMC which I gladly accepted though it deviated from my interest in child neurology. Together with Dr. Brigido Carandang, who at that time, just arrived from the University of California, Davis, I owe the foundation of my knowledge and skills in neurology and the discipline of inquisitiveness, research, teaching, and organization. My thanks to the Japanese Government for the Monbusho Scholarship Grant. To my sensei, Prof. Yoshigoro Kuroiwa and Prof. Motohiro Kato who allowed me to explore new pursuits in neurology, neurophysiology, and research; and to the other sensei, colleagues, residents and staff of Kyushu University Neurological Institute who catered to my needs during my fellowship, domo arigato gozaimashita!

My sincere appreciation to my colleagues at the Philippine Neurological Association (PNA) and Asian and Oceanian Association of Neurology (AOAN) — two organizations of neurologists dedicated to share knowledge with one another. I am a proud recipient of these academic exchanges. Friendships evolved in these interactions and I am fortunate to have this with Prof. Bhim Singhal who holds my utmost respect. Thank you Bhim for writing the foreword of the book.

Sincere thanks to, Cora Derige, the line editor, who met with me several times to improve the content of the drafts and painstakingly tried to understand medical terms to develop the text; to Josephine Reyes Arce who labored in proofreading the draft that contained strange medical terms; and to Dr. Rene Mendoza who reviewed the initial part of the book and provided encouragement. My appreciation to Ryan Abainza, who transformed my drawings to digital illustrations. Sam Penaso, an International Artist from the picturesque island of Bohol, Philippines, though I had not met personally, willingly permitted to use his beautiful painting, Humanscape, that coincidentally depicted the very essence of this book. My classmate and good friend, Cooper Resabal, facilitated the link with this great art work. My thanks to both of you.

My daughter Nikki, the real writer in the family is my consultant, who provided valuable insights and suggestions during the writing process and critical guides to help me navigate the nuances of writing. My two daughters who are also neurologists, Hana and Carmela, gave critical recommendations and opinions. To my other children and their partners who provided the cheers in this effort, Caru and Catherine, Fatima and Miko, Patrick, Darren, Miguel, Malou, and Maan. Thanks my valuable kids. My kisses of love to my grandchildren, Cy, Cerrah, Lucy, Franco and Cito who provided comfort when the stresses of writing came my way.

My beautiful and loving wife, Cynthia, patiently prodded, nudged, and pushed me and offered all emotional and material support. She kept on reminding me to be direct and to keep the sentences short. She is my inspiration. Without her this book will not see the light. Thank you dear wife.

Gratitude to the medical students of Class 2014 of St. Luke’s College of Medicine Willliam H. Quasha Memorial who gave their time to read the first draft and provided their comments and suggestions. My appreciation to Dr. Annie De Leon, Medical Director of Quirino Memorial Medical Center for granting a sabbatical that allowed me to write. My colleagues who were invited to critique parts of the book provided valuable guides. These are: Dr. Dede Gunawan, Dr. Artemio Roxas Jr, Dr. Arnel Malaya, Dr. Carmelita Divinagracia, Dr. Dada Mesina-Nepomuceno, Dr. John Carlo Timbol and Dr. Deborah Bernardo. To all my students, residents, nurses, physical therapists, neuroscience colleagues, friends and patients, thank you. I learned so much from all of you.

To my parents, Mario and Jesusa, thank you for your prayers, guidance and sacrifices.

Neurology in Our Midst

(A Primer to Neuroanatomy and Clinical Neurology)

FOREWORD

I am indeed honored to have been invited to write the foreword for Professor Amado San Luis’ book ‘Neurology in Our Midst’—A Primer to Neuroanatomy and Clinical Neurology. Neurology has long been considered as a specialty which ‘inspires awe’ among the medical fraternity. It is not uncommon for medical students & resident doctors to get cold feet when confronted with a Neurology case in the exam or during ward rounds.

Professor Amado San Luis has written this book with the primary objective of dispelling this ‘fear psychosis’ surrounding the study of Neurology. This book is a refreshing change from the standard neurology textbooks. Rather than focus on neurological diseases & syndromes, the author discusses the anatomical pathways to explain how a particular symptom & finding originates. While seeing a neurological case, the first and most important step is to determine where the lesion lies. Sound knowledge of neuroanatomy alone can guide us to the precise localization & thus aid the correct diagnosis & management.

The Professor’s mastery of the subject is reflected in the way he holds the reader’s hand and guides him through the maze of information, consolidating the basic concepts of Neuroanatomy and Neurophysiology along the way. Case studies with clinic-anatomic correlations and a brief review of diagnostic possibilities are to me the stand out feature in each chapter. The several illustrative diagrams further add to the value of the book.

The book has been written in a clear, concise style – easy to read & comprehend. One looks forward to reading the next page and then the next and so on. This is no mean achievement. I must compliment Professor Amado San Luis who has used his vast experience of teaching for over three decades to write this very informative book. I am sure it will be more than useful for medical students, nursing staff, health care professionals & all those who care for persons with neurological illnesses.

signature.jpg

Bhim Singhal MD, D.Sc (Hon.), FRCP (London & Edin), FAMS

Director of Neurology

Bombay Hospital Institute of Medical Sciences

Former Professor & Head of Neurology Grant Medical College & Sir J.J. Group of Hospitals

Mumbai, India

PREFACE

Neuroanatomy is my most difficult subject in medicine! doctors’ complain.

A family practitioner said, I hated my rotation in neurology after seeing a comatose patient. I had a dreadful experience.

I often fear questions that relate to patients with strokes… I am just not confident to answer them. – shared by a physical therapist.

Every time neurological patients are in our care, there is this constant fear in me that patients might die anytime! … lamented by a registered nurse in a hospital.

Dread, difficulty, insecurity, helplessness, and fear are everyday experiences shared by doctors, nurses, physical therapists, and caregivers — health care providers, who are given the inescapable task to meet the demands of patients with neurological diseases. Patients afflicted with sudden or long-term brain diseases or injuries, and their families, experience distressing uncertainty and will demand reliable and understandable answers to questions such as, What happened?, How did it happen?, What should be done?, and What will happen? Queries are anxiously repeated as often as clinical changes happen and until a satisfactory response to their questions are met. The responsibilities faced by the healthcare providers look formidable and pre-existing disdain of neurological cases has compounded the situation. These negative feelings had its formative years when medical students, nurses and other care providers studied neuroanatomy and clinical neurology. It was at this stage when neurology, to some extent, was so feared that it led to a condition called neurophobia.

Jozefowicz described Neurophobia in 1994 as fear of the neural sciences and clinical neurology that is due to the students’ inability to apply their knowledge of basic sciences to clinical situations [1,2,3]. In the three decades of teaching neurology, I came to notice that medical students, residents, general practitioners, nurses, and physical therapists widely share this fear. I have also observed this attitude of fear create a wide communication gap between patients and their families and health care providers. There is, therefore, a need to lessen, if not eliminate, neurophobia among health care providers. Thus this book.

The book is designed to be read by medical and nursing students and physical therapists before starting their journey to neuroanatomy and clinical neurology and before beginning clinical rotations. The book serves as a neurology map that will provide the prospective neuroscience students a view of where one is going and what to expect. The emphasis is to understand how our brain and body usually function during our daily activities and how diseases or injuries can change them. The reader is not expected to memorize functional structures seemingly in preparation for an exam. This primer does not aim to replace the usual medical books prescribed in neuroanatomy and clinical neurology. This strategy provides clinical meanings to boring anatomic structures that students are expected to memorize. Examples of how neuroanatomic functional structures are examined to unravel abnormalities are included. The process will help in localization, diagnosis and, ultimately, to treatment.

The regular activities and functions of people are dissected, as to, how the nervous system weaves its various parts to make them happen. The exploratory journey is punctuated by breaks to mention some diseases or injuries that affect the functions of the nervous system. Examples of case stories based on actual patients are modified to enhance clinical-anatomic correlations. The names of the characters of the stories are creations of the author. Some neurological examinations are described to serve as triggers to pursue the development of these skills which are not purely mechanical but associated with physio-anatomic understanding. Repetitions are liberally used to facilitate comprehension. Neuroanatomic details of the thalamus and hypothalamus are limited to their participation in some functions. Illustrations were done by the author to emphasize that anybody can do simple drawings to facilitate grasp of functional anatomy. The readers are encouraged to freely trace the directions and connections of neural structures by using different colors that would enhance understanding. Tables are limited and are used to emphasize some points in the discussion. Some contents of the book may catalyze one’s mind to understand particular topics. Google those topics. Follow the interests of your brain. There might be a neuroscience talent within. The intended beneficiaries of this book are ultimately the patients afflicted with neurological diseases and the medical providers who will be tasked to help.

INTRODUCTION

Everything that we do has its origin, control, termination, and processing in the nervous system, a compelling reason why one should at least get a good idea of how the brain works. Even when sleeping, the mind never stops working. Look at the people around you. See how they walk, the accompanying body movements, the speed, the balance, the directions they set, their decisions to hurry or to stop, their avoidance to bump each other even while some are talking through their I-phones. All these people are in amazing assortments of fluid activities, but not one has a conscious idea about how delicate and precise the brain integrates the complex nervous system to make what you have witnessed happen. Then one person with a limp and pace slower than those of the rest strikes your attention. He makes you wonder why he was different. Could it be that his brain function has been disturbed and has adapted to the need to travel? While reading this and imagining what the text is describing, your brain is integrating all the learned information, as well as the unlearned when you were still in your mother’s womb, to form a system of communication. When your friend taps you on the shoulder, he recognizes you through his memory; his smile is made possible by the finite control of the muscles of the face while your memory cells likewise influenced your response. Your interpretation of the smile is yours alone, a recognition of friendship, much of which is integrated by your limbic system, the seat of emotion. Neurology, the study of the nervous system, is all around us and within us, in our midst.

The General Plan, Direction and Goals

1018.png

When planning a journey, one has to identify the destination, set the direction, organize the system (needed clothes, accommodation, tickets, maps, budget, etc.) and processes (addresses, time, dates, terminal, schedules, etc.). The same holds when one intends to understand a neurological problem. The goal is to arrive at a neurological diagnosis, the foundation that allows treatment plans. The procedure is to break the journey into six essential steps. This book shall provide the first four steps of acquiring knowledge and processes that will prepare one for the fifth and sixth notches which are the reader’s utilization of various information that one will assimilate in clinical neurology. The steps, however, are blurred because to appreciate the application of neuroanatomy to clinical neurology one should look at the process as a continuum of normal and disturbance of functions. What makes neurology different is the emphasis on localization which to some is daunting or merely a turn-off. You will find out after persevering in reading this book that you do not need a GPS to locate most of the problems. Where signs and symptoms intersect is usually where the lesion is. Establishing symptoms and relevant neurological examination findings are the framework for arriving at a preliminary diagnosis that will guide one to choose the appropriate and the most economical diagnostic tool. Understanding the meaning of abnormal neurological examination findings are very much crucial in establishing clinical parameters that will tell one if the patient is getting worse or getting better — critical factors in clinical judgment that cannot be replaced by any diagnostic armamentarium.

ANATOMIC ORIENTATION

figure1.jpg

Figure 1. Anatomic terms used relative to the body parts of quadripedal animals and bipedal humans.

Neuroanatomy makes use of anatomic landmarks just like any maps for proper orientation and common language. Maps use the basic north, south, east, and west positions and could be a combination of NE or NW, etc. Human anatomy uses similar combinations. It is interesting to know that in the past, comparative or animal anatomy, particularly on four-legged animals was the basis of the knowledge of human brain structures. It is from this orientation that early anatomists used the term dorsal which referred to the posterior or back part; ventral, the anterior or front portion; and lateral, to the outer side; and medial, to the inner side (Fig. 1). These were the terms used when describing the external and internal anatomies of the four-legged animals. The labels included the tip of the head or cephalad or rostral and caudal area or towards the tail. This quadrupedal animal orientation remained through the Renaissance period until human cadaver studies were made possible on two-legged homo sapiens whose ancestor is the Homoerectus in 2,000,000 BC. The shift of quadrupedal posture to bipedal or erect posture can make anatomic orientation confusing. An example is the front or anterior of dogs can be confused as in the front of the face when it is actually cephalad. In humans, the anterior is consistently in the front of the face.

When one reads the anterior grey horn of the spinal cord, it refers to the front portion of the grey matter. Anterolateral-Spino-thalamic fibers mean that the fiber tracts are located lateral and slightly in front of the spinal cord. An extra clue is that the direction of the thread is from the spine and will end at the thalamus. Ventroposteromedial thalamus means the location is at the base, posterior, and central part of the thalamus. (Note that the thalamus is positioned horizontally like a boat in an erect human brain). After a while, as you read the book, you will gradually adopt the language of neuroanatomic landmarks just like how you learned your first language.

"Afferent" and "efferent" are terms used to describe the direction of impulses. These are the terms reflex functions often used. There are two arms in the reflex: the initiating stimuli, afferent or entering (to the CNS) arm, and the transmitting response, efferent or exiting arm. An example of this reflex is the pupillary light reflex. The afferent or entering arm of the optic nerve transmits the light stimulus while the efferent or exiting arm is the parasympathetic fiber of the oculomotor nerve that carries the response and effect a pupillary constriction. It is a little different inside the brain. The afferent or efferent impulses are inside the nervous system. Examples are the afferent impulses from the hypothalamus to the Salivatory nucleus of the medulla, whose efferent neurons would send electrical signals through the glossopharyngeal nerve effecting or causing salivary secretion. We will use the terms, afferent and efferent arms, to describe the direction of impulses.

Terms are also used to describe the distance of parts from a central position. The heart is the center of the blood vessels, so arteries or veins near it are described as proximal vessels (proximately near) whereas the remote branches are called distal vessels (distant vessels). The central station of the peripheral nerves, on the other hand, is the spinal cord, so the nearest branches to the spinal cord are called proximal nerves in contrast to the distal nerves termed as such because they are the faraway branches or end of the nerves. Distance from the trunk or muscles above describes muscles as distal or proximal. Muscles of the hands are distant when related to the forearm. Some diseases involve proximal more than distal parts. Examples are diseases of the muscles, one of which is hypokalemic (low potassium) myopathy. Hypokalemia can manifest as proximal muscle weakness where the person is unable to raise the arms but can give a firm hand grip.

The subway train system where travelers from the central station stop or connect at different substations is like the neural interconnections in the central nervous system. The ganglia are like the substations where interconnections with a group of neurons happen outside the central axis. An example of this is the sympathetic ganglia where the sympathetic neurons from the spinal cord interconnect with the ganglionic neurons at the cervical level of the spine. The most prominent of the ganglia is the dorsal ganglia where all sensory impulses to the brain and spinal cord pass through. All dorsal ganglia host pseudo-bipolar sensory neurons which are unique because they seemed to have two axons but only one functional unit. One axon transmits sensory stimuli from the periphery of the body while the other pass on the impulses to the spinal cord. Though without synaptic connections, the bipolar neurons transmit impulses to the spinal cord.

There are various substations inside the brain and spinal cord where a group of neurons serves as simple relay stations with specific inhibitory or excitatory mechanisms. The spinal cord grey matter has organized islands of neurons called laminae with precise functions.