Rapid Neurology and Neurosurgery

By Kumar Abhinav, Richard Edwards and Alan Whone

Rapid Neurology and Neurosurgery is a must for all medical students and junior doctors - it is a quick and easy on-the-ward or clinic reference and the perfect revision tool for those approaching finals, undergraduate neurology and neurosurgery examinations, and the Membership of Royal College of Surgeons (MRCS) examinations.

It provides a concise, structured approach to neurology and neurosurgery learning, covering key facts in a simple and memorable way:
Part I - The Basics - features the basic principles and facts essential for a good understanding of neurology and neurosurgery and includes sections on relevant neuroanatomy; neurological history and examination; and investigations including neurophysiology and neuroradiology. MRI and CT scans are included throughout the text.
Part II - Complaints: face to face with the patient - features OSCE-style and the viva-voce examination preparation and has chapters on presenting complaints with relevant and selected questions to ask for establishing the differential diagnoses (presented in a table) with basic investigations and management.
Part III - Conditions: applying the basics - presents important clinical conditions with sections on definition; epidemiology; aetiology; associations/risk factors; pathology; history; examination; investigations; management; complications; prognosis and a list of differential diagnoses usually in a table with general clinical information and distinguishing information to exclude the alternative diagnoses.

Each chapter also includes key points to remember and highlights key facts.

Rapid Neurology and Neurosurgery contains only the essential, core, and relevant facts in a concise, pocket-sized, 'rapid' refresher providing a thorough foundation of neurology and neurosurgery knowledge allowing you to excel in the examinations.

• Language: English
• Publisher: Wiley
• Release date: Jun 29, 2012
• ISBN: 9781118308516

Book preview

Part I

The Basics

Chapter 1

About this Book and How to Use it

The principal purpose of this book is to act as a quick revision tool for medical students approaching finals or other undergraduate neurology/neurosurgery exams. Although the book is intended as a quick revision tool, using it diligently and devoting time to understanding the basic concepts outlined herein will allow you to neurologically flourish rather than simply pass exams. The book is designed for both the newer type of written exams, including multiple choice questions (MCQ) as well as the extended matching questions (EMQ), and traditional exams requiring long and short answers. This book is also designed to prepare you for the Objective Structured Clinical Examinations (OSCE); in particular, Part II is geared towards this purpose.

The book is divided into three parts. Part I gives you the necessary basic principles and facts essential for building a foundation in clinical neurology/neurosurgery at an undergraduate level. Only clinically relevant neuroanatomy is presented along with an introduction to the topics of neurological history, examination and investigations. In particular, we have tried to simplify neuroradiological concepts and presented the rationale for using different imaging modalities.

Part II is very much geared towards the OSCE and the viva voce exams in finals. This section consists of chapters dealing with various presenting complaints. Lists of focussed and discriminating questions for determining the important differential diagnoses are included in these chapters along with tables listing the relevant disease entities in order of incidence. Please note, however, that you will also be expected to ask other relevant questions not listed in the chapters while taking a detailed history, including past medical history, drug history and social history. Additional important clinical information for each presenting complaint is included. The tables of potential differential diagnoses are supplemented by information on basic investigations and management. Again, in an exam setting you will have to be guided by the clinical information and suggest a list of focussed and relevant investigations! This part of the book can also act as a worthy quick reference on wards and in clinics.

Part III presents the important clinical neurological and neurosurgical conditions with focussed pertinent clinical information. Neurological topics are presented first followed by neurosurgical topics with the exception of the chapter on subarachnoid haemorrhage, which is included under ‘stroke’. Part III like other parts is interspersed with sentences beginning with ‘Remember . . .’ and designed to highlight key facts from the chapter. At the end of each chapter there is a list of common differential diagnoses (up to a maximum of four–five) for the particular condition described. General clinical details are provided, including, where applicable, information that can be used to distinguish between or exclude the alternative conditions. This should be of particular help for the EMQ section of the exam and will also prove useful in the OSCE when presenting a list of potential differential diagnoses.

Some of the chapters in the book may not strictly follow the format as laid out above and will generally be due to the nature of the topic and thereby the limitations of presenting it in a specific format.

We hope that the format; organisation and simple language employed will facilitate quick and effective revision and will help you perform well in all sorts of undergraduate examinations. Moreover, we trust this book will permit a better understanding of the basic concepts underpinning neurology and neurosurgery and thus provide a firm basis upon which to build your clinical neurological/neurosurgical expertise as you journey through your medical career.

Good Luck!

Chapter 2

Basic Neuroanatomy

The following section aims to present only the very relevant anatomical information.

Cortical Anatomy

Figure 2.1 demonstrates the following relevant key areas on the cortical surface:

Figure 2.1 Lateral surface of cerebral hemisphere demonstrating cortical surface anatomy.

Remember: The association between dominant hemisphere and speech areas and therefore a further important point about ascertaining handedness of patients at the beginning of obtaining a neurological history.

Figure 2.1 Lateral surface of cerebral hemisphere demonstrating cortical surface anatomy.

Primary motor cortex: Situated anterior to central sulcus (frontal lobe) in the precentral gyrus; involved in contralateral motor function—Brodmann's (Br.) Area 4.

Primary somatosensory cortex: Situated posterior to central sulcus (parietal lobe) in the postcentral gyrus; involved in contralateral sensory function—Br. Areas 1, 2 and 3.

Motor speech area: In the dominant hemisphere only (left hemisphere for right-handed subjects and usually left hemisphere for left-handed people); anatomically situated in the inferior frontal gyrus (pars triangularis and opercularis); also known as ‘Broca's area’ and involved in speech output—Br. Area 44.

Wernicke's area: In the dominant hemisphere; anatomically situated in the supramarginal gyrus—Br. Area 40 (part of inferior parietal lobule) and posterior part of superior temporal gyrus; involved in comprehension of speech.

Primary visual cortex: In the occipital lobe adjacent to the calcarine sulcus—Br. Area 17; part of the visual pathway.

Brainstem and Cranial Nerves (CN)

The midbrain is the most rostral part of the brainstem; CN III (oculomotor) and IV (trochlear) arise from the midbrain. The pons is situated between the midbrain and the medulla with CN V (trigeminal), VI (abducens), VII (facial) and VIII (vestibulocochlear) nerve entering into or exiting from ventral pons. The medulla is caudal to pons being continuous with spinal cord. Fibres of the CN IX (glossopharyngeal), X (vagus) and XII (hypoglossal) nerves enter into or exit from the ventral aspect of the medulla. The basic clinical features of lesions associated with cranial nerves are presented in Table 3.3.

Remember: An easier simplified way of remembering the site of entering or exiting of CN from brainstem is 2, 4 and 4, i.e. apart from first two cranial nerves, CN III and IV from midbrain with V–VIII from pons and IX–XII from medulla.

Cerebellum

Cerebellum consists of the midline vermis, two cerebellar hemispheres and a flocculonodular lobe. Primary role of the cerebellum concerns the planning and fine-tuning of the movements. The cerebellum exercises its influence on the contralateral upper motor neurones in the cerebral cortex and brainstem. The vermis specifically has a role in trunk muscle control with lesions resulting in truncal ataxia.

Remember cerebellar lesions result in ipsilateral deficit.

Vascular Anatomy (Cranial)

Figure 2.2 demonstrates the Circle of Willis at the base of the brain. CNS arterial supply is provided by a pair of internal carotid arteries (dividing into terminal branches of middle and anterior cerebral arteries) and a pair of vertebral arteries (uniting to form midline basilar artery at the junction between pons and medulla) forming the Circle of Willis. In terms of cerebral hemisphere, the blood supply is grossly as follows: anterior cerebral artery predominantly supplies the medial surface of the frontal and parietal lobes, including the motor and sensory cortices for the contralateral lower limb; middle cerebral artery with the largest cortical territory supplies almost the whole of the lateral surface of frontal, parietal and temporal lobes, including the speech areas in the dominant lobe, primary motor and sensory cortices for the contralateral whole body excluding the lower limb; posterior cerebral artery (derived from basilar artery) supplies the inferomedial temporal lobe and the occipital lobe, including the visual cortex. The vertebrobasilar system as a whole supplies brainstem, cerebellum and occipital lobe.

Figure 2.2 Circle of Willis at the base of brain.

With respect to internal capsule, the blood supply is derived from anterior choroidal artery arising from internal carotid artery, lateral striate branch of middle cerebral artery and recurrent artery of Heubner arising from anterior cerebral artery. The blood supply of basal ganglia is also derived from these arteries.

Spinal Cord

The vascular supply of the spinal cord is derived from radicular arteries arriving from the aorta. Artery of Adamkiewicz is the main arterial supply for the spinal cord from T8 to conus. Midthoracic region being a watershed zone is susceptible to vascular injury leading to ischemia or infarct. Figure 2.3 demonstrates a cross section from the spinal cord, including the intermediolateral column, representing sympathetic outflow and present from T1–L2. It is worth reviewing briefly the anatomy of the three tracts as outlined below from a basic Neuroanatomy text. The basic clinical information regarding these three tracts is as below:

Lateral corticospinal tract: Skilled movement (serving ipsilateral side).

Lateral spinothalamic tract: Pain and temperature sensation (serving contralateral side).

Dorsal column: Fine touch, joint position and vibration sense (serving ipsilateral side).

Peripheral Nervous System

Important muscle groups with their spinal roots, named nerve supply and actions to test, are summarised in Table 3.5. Similarly, a dermatomal map demonstrating the dermatomes needing examination during a routine neurological exam is included in Chapter 3.

Figure 2.3 Cross section of spinal cord.

Chapter 3

Neurological History, Examination, Signs and Localisation

This chapter is not intended to be exhaustive but rather is a brief summary of taking a neurological/neurosurgical history and performing a neurological examination. Here, we provide an overview of the process and a framework which allows a neurological diagnosis to be reached.

One classical way of coming to a list of potential differential diagnoses when faced with a neurological/neurosurgical patient is to adopt the so-called where, what and why approach.

‘Where’

It is often the case that the neurologist or neurosurgeon, when confronted with a patient, will first ask themselves, where is the lesion?, meaning where is the predominant focus of pathology within the neurological system.

The lesion may be at a single focus within the nervous system, such as entrapment of the median nerve at the wrist in the case of carpal tunnel syndrome or entrapment of an L5 nerve root in a patient with foot drop. Alternatively, the lesion may be multifocal, as in multiple sclerosis (MS) where demyelinating plaques may be found throughout the brain and spinal cord, or it may be diffuse or generalised, as in the case of encephalopathic patient with a reduced level of consciousness secondary to a systemic infection or metabolic derangement.

In some instances, gross localisation is very straightforward, for example, in a patient with traumatic brain injury post a road traffic accident, it is relatively implicit to focus localisation within the brain. In case of a patient complaining of weak legs (see Chapter 9), the problem could however variably be within the brain, brainstem, spinal cord (central nervous system (CNS)) or within the anterior horn cell, nerve root, lumbar sacral plexus, peripheral nerves or neuromuscular junction (peripheral nervous system (PNS)) or be isolated to skeletal muscle. In the latter scenario, the neurological examination is pivotal to localising the problem where, for example, upper motor neurone (UMN) signs will point to a problem in the central nervous system and lower motor neurone (LMN) signs will point to a problem in the peripheral nervous system. The distribution of signs will also point towards the potential site of the lesion; therefore, hemisphere lesions usually lead to contralateral weakness affecting face, arms and legs, variably depending on the exact site of the lesion, whereas a cord lesion usually produces bilateral weakness with possible evidence of LMN signs at the level of the lesion and UMN signs below the level of the lesion with a sensory level. Patients may present with typical syndromes (Table 3.1) observed with pathology in different parts of the CNS, thereby further helping in localisation (also refer to Chapter 35).

Table 3.1 Key areas within CNS with description of clinical syndromes related to pathology.

‘What’

Having decided where the lesion lies, the next question to consider is what is the problem? Here we are thinking particularly of the aetiological group to which the potential diagnosis belongs. This is typically based upon the temporal sequence of events largely elicited by obtaining the history of the presenting complaint (Table 3.2).

Table 3.2 Potential causative groupings along with brief temporal and other clues associated with a particular aetiological group.

‘Why’

Having decided where the potential lesion lies and also to which causative group the diagnosis may belong, the next step is to consider why might this disease or entity have occurred?. For example, the patient presenting with acute onset of right arm weakness and language disturbance is likely to have an abnormality localising to the left frontal lobe with the sudden onset suggesting a vascular cause. The question then arises regarding the reason for the occurrence of the vascular event. With a preceding history of trauma, an extradural haemorrhage may be the explanation, whereas a past history of smoking, diabetes and hypertension might point more towards an ischaemic stroke. This gathering of information regarding such associated factors should be covered in the history of the presenting complaint and other components such as the past medical history, the medication list, family history and social history.

The Neurological History

Many of the questions pertinent to be asked when considering patient complaining of specific neurological symptoms are covered in Parts II and III of this book dealing with presenting complaints and specific disease entities, which may be referred to when confronted with specific neurological complaints. Below are some additional points that should be