ENGLISH FOR HEALTH SCIENCES. Nervous System

Transcription

1 Nervous System

2 Table of Contents HOW IT WORKS... 4 ANATOMY... 4 Central nervous system (CNS)...4 Brain...4 Spinal Cord...5 Peripheral nervous system (PNS)...5 NEUROLOGICAL CONDITIONS... 5 Serious Diseases...5 Tests and diagnoses...6 Surgeries and procedures...6 Medicines...7 GLOSSARY... 8 Terms and Abbreviations...8 CASE STUDIES Confusion Confusion

3 Nervous System English for Health Sciences 3

4 Nervous System HOW IT WORKS The Nervous system is the chief controlling and coordinating system of the body. It controls and regulates all activities of the body, whether voluntary or involuntary, and adjusts the individual (organism) to the given surroundings. It directs all body systems and cells and is responsible for all thought, emotion, sensation and movement. The nervous system is divided into two major systems: the central nervous system (consists of the brain and the spinal cord) and the peripheral nervous system (consists of the nerves outside of the brain and spinal cord). Each is vital to human survival and functioning. Did you know...? The Neurological System is commonly referred to as the Nervous System ANATOMY The nervous system is divided into 2 major systems: Central nervous system (CNS) and Peripheral nervous system (PNS) Central nervous system (CNS) Serves as the main processing centre for the entire nervous system, and controls all the workings of your body. CNS is divided into Brain and Spinal Cord. Brain The brain is the control centre of the body. It consists of three main components: the forebrain, the midbrain and the hindbrain. Forebrain: responsible for a variety of functions including receiving and processing sensory information, thinking, perceiving, producing and understanding language, and controlling motor function. It contains structures such as the thalamus and hypothalamus and cerebrum. 4

5 Midbrain: connects the hindbrain and the forebrain. This region of the brain is involved in auditory and visual responses as well as motor function. Hindbrain: extends from the spinal cord and contains structures such as the pons and cerebellum. These regions assist in maintaining balance and equilibrium, movement coordination, and the conduction of sensory information. The hindbrain also contains the medulla oblongata which is responsible for controlling such autonomic functions as breathing, heart rate, and digestion. Spinal Cord The spinal cord is a cylindrical shaped bundle of nerve fibres that is connected to the brain. The spinal cord runs down the centre of the protective spinal column extending from the neck to the lower back. Spinal cord nerves transmit information from body organs and external stimuli to the brain and send information from the brain to other areas of the body. The nerves of the spinal cord are grouped into bundles of nerve fibers that travel in two pathways. Ascending nerve tracts carry sensory information from the body to the brain. Descending nerve tracts send information pertaining to motor function from the brain to the rest of the body. Did you know...? Nervous stimulus inside our brain can travel faster than 400 km per hour. Peripheral nervous system (PNS) The peripheral nervous system consists of 12 pairs of cranial nerves and 31 pairs of spinal nerves. The cranial nerves carry or transmit impulses between the brain, the head, and the neck. The spinal nerves relay messages between the spinal cord, the chest, abdomen, and the extremities. The functions of the spinal and cranial nerves are mainly voluntary, involving smell, taste, sight, hearing, and muscle movement. The peripheral nervous system then divides into two parts: the somatic system and the autonomic system. The autonomic system further divides to include sympathetic and parasympathetic systems. All subdivisions connect in some way to perform their functions, but they all remain part of the main nervous system. NEUROLOGICAL CONDITIONS Serious Diseases 5

6 Wernicke-Korsakoff Syndrome: This disease, notably frequent among chronic alcoholics, is due to a deficiency of vitamin B 1 or thiamine. The poor diet of alcoholics who are suffering from this syndrome leads to lesions and increased microhaemorrhages in the mammillary bodies, thalamus and brainstem. Alzheimer's : Is the most common cause of dementia in western civilisation. It causes problems with memory, thinking and behavior. Symptoms usually develop slowly and get worse over time, becoming severe enough to interfere with daily tasks. Broca Aphasia: Loss or impairment of the power to use or comprehend words usually resulting from brain damage. Parkinson s Disease: Parkinson s disease (PD) is characterised by a slowing of voluntary movements, bradykinesia, muscular rigidity and tremor at rest. These abnormalities result from a reduction of neurons that make dopamine in the pars compacta of the substantia nigra. Tests and diagnoses The following list of available procedures includes some of the more common tests used to help diagnose a neurological condition. Biopsy: involves the removal and examination of a small piece of tissue from the body. Brain scans: imaging techniques used to diagnose tumors, blood vessel malformations, or hemorrhage in the brain. These scans are used to study organ function or injury or disease to tissue or muscle. Types of brain scans include computed tomography, magnetic resonance imaging, and positron emission tomography (see descriptions, below). CT scan: A CT scan (or Computed Tomography scan) is a noninvasive, painless process used to produce rapid, clear two-dimensional images of organs, bones, and tissues. Neurological CT scans are used to view the brain and spine. EEG: An EEG (Electroencephalography) monitors brain activity through the skull. Evoked potentials: Evoked Potentials (also called evoked response) measure the electrical signals to the brain generated by hearing, touch, or sight. MRI Scan: An MRI (Magnetic Resonance Imaging) scan uses computer-generated radio waves and a powerful magnetic field to produce detailed images of body structures including tissues, organs, bones, and nerves. Myelography: A Myelography involves the injection of a water- or oil-based contrast dye into the spinal canal to enhance x-ray imaging of the spine. PET Scan: Pet (Positron emission tomography) scans provide two- and three-dimensional pictures of brain activity by measuring radioactive isotopes that are injected into the bloodstream. SPECT: SPECT (Single Photon Emission Computed Tomography) is a nuclear imaging test involving blood flow to tissue used to evaluate certain brain functions. Ultrasound imaging: also called ultrasound scanning or sonography, uses high-frequency sound waves to obtain images inside the body. Surgeries and procedures 6

7 Most surgeries of this system involve removal of tumours in the brain itself, whether malignant or benign. Tumours of the spinal cord can also be removed surgically. Surgery on the brain and the spinal cord is very involved and detailed, due to the complexity of nerves and the tissue involved. Craniotomy: Surgical cutting into and opening the skull to gain access to the brain tissue for surgery Laminectomy: Excision of the posterior arch of a vertebra Neurectomy: Excision of a nerve Neuroplasty: Surgical repair of a nerve Medicines Here are some common types of medications used to treat disorders and conditions of the nervous system: Anticonvulsants, hypnotics, and sedatives are used to treat various types of seizures. CNS stimulants are used to treat attention deficit disorders. Cognition adjuvant therapy is given to treat Alzheimer s disease. Hypnotics are used to treat sleeping disorders; examples include barbiturates and nonbarbiturates. 7

8 GLOSSARY Terms and Abbreviations Here are some of the most common abbreviations that you can memorise to make communicating about the Nervous System Abbreviation What It Means Abbreviation What It Means ANS Autonomic Nervous System GP General Practitioner (Family Doctor) CNS Central Nervous System MRI Magnetic Resonance Imaging CSF Cerebrospinal Fluid PD Parkinson Disease CT Computed Tomography PET Positron Emission Tomography CVA Cerebrovascular accident PNS Peripheral Nervous System EEG Electroencephalography TIA Transient Ischaemic Attack ENG Electronystagmography Some Neurological-related words: Word Aphasia Bruit Dementia Grey matter Neurologist Neurology Neurons White matter What It Means Condition of being without speech Abnormal sound upon auscultation Mental decline Brain tissue. Consists of aggregations of neuronal cell bodies Physician who specialises en neurology, the scientific study of the nervous system The branch of medicine dealing with the study of the nervous system, functions and disorders The basic units of the nervous system. All cell of the nervous system are comprised of neurons Brain tissue. Consists of neuronal axons that are coated with myelin 8

9 Now let s start building some vocabulary. Here you have a lists prefixes and suffixes associated with the nervous system. Let s start with the prefixes: Prefix Hemi- Para- Polio- Quadri- Sub- What It Means Half Beyond, around, beside Grey Four Below, under Next, we will move on to suffixes. Suffix -algia -itis -malacia -paresis -plegia -schisis -thenia -us What It Means Pain Inflammation Softening Slight paralysis Paralysis Cleft or splitting Lack of strength Condition 9

10 CASE STUDIES Confusion 1 History The GP has been helping to look after a patient with Parkinson s disease, who was diagnosed with the condition 1 year earlier. The patient has been visiting the Parkinson s Clinic regularly and has been on Sinemet for 1 year and is now on Sinemet plus. He is still playing bowls and going on holidays but is finding that he is sleepy and tired, and getting more forgetful. He is also having problems with his short-term memory and on two occasions he even got lost in his own house. In addition, he finds that he is having difficulty rolling over in bed and fell out of bed when he was staying with his son in Scotland a few weeks previously. The GP does a simple assessment. The patient scores 9 out of 24 on the Epworth Sleepiness Scale, a negative result in terms of a sleep disorder. On the Folstein s mini-mental state examination he recalled three named objects immediately but only one out of the three at 5 minutes. The patient is unable to read and write properly as the war interrupted his studies so the rest of the test is difficult. However, he can draw the intersecting pentagons and obey the three stage command. He did, however, have difficulty with repeating No ifs, ands or buts. The results are suggestive of cognitive impairment. Questions What does the GP do next? What other health-care and social-care practitioners would be of assistance in this situation? Answer The GP refers the patient back to the Parkinson s Clinic and the specialist makes no change to his medication but refers him for neuropsychometry for assessment. He also refers him for some physiotherapy. He sees him again in 6 months and the patient reports that he is now feeling uncomfortable is bed, claustrophobic and hot and is getting out of bed up to 10 times in 1 hour. This is a problem for both him and his wife as getting in and out of bed is difficult. As a result, neither of them is getting much sleep. His hand tremor is also getting worse. Unfortunately, he did not go for neuropsychometry as he felt embarrassed to do so. The specialist suspects that he is actually going off in bed and adds some more Sinemet last thing at night. He also encourages him to continue with the physiotherapy as this is helpful and go for his neuropsychometry testing. He is seen again 6 months later when the patient reports hallucinations when he sees familiar people and animals that have passed away some years previously. He still has not gone for his testing and is not keen to do so and so this is shelved. The specialists explain to him and his wife that his hallucinations and confusion may be caused by dementia with Lewy bodies. They add entacapone to his Sinemet to try and improve his symptoms at night. Unfortunately, within a few days of starting the entacapone he develops worsening hallucinations and, despite stopping the medication, the hallucinations continue and cause him and his family distress and confusion as he 10

11 is not sure what is real and what is not. His physical symptoms of Parkinson s are under good control and so the specialist suggests cutting back the Sinemet slowly to see if it is excessive dopamine that is causing the hallucinations. Quetiapine is added for his psychological problems but this has no definite benefit and in fact seems to make him more confused and slow. He is therefore put onto rivastigmine. The Parkinson s disease nurse specialist and the GP arrange a social service referral and a daily care package is put into effect. The most difficult time for his wife is at night as the patient tends to get out of bed and roam round, and she is worried that he will fall or wander out of the house. A night sitter is arranged for two nights a week so that his wife can have some proper sleep. The patient also is signed up for a day centre. Key Points Dementia is an extremely difficult condition to deal with and can be frightening and gruelling for the patient (and their carers). A multidisciplinary team approach is vital in providing proper treatment and support for the patient and their family. Regular follow-up and medication review is essential as symptoms and circumstances can constantly change. Confusion 2 History The GP is asked to call on an 89-year-old widow, who has lived in her own bungalow since her husband died a few years ago. She has Type II diabetes, controlled with diet and metformin, and is handicapped by gradually worsening macular degeneration. Her memory for recent events is faulty, and she has fallen once or twice, on one occasion fracturing her pelvis which necessitated admission to hospital and a painful recovery. It is becoming clear to her daughter, if not to herself, that she is finding it difficult to care for herself, even with a daily home help. She has finally been persuaded to move in to her daughter s home, which has been adapted to offer a convenient granny flat on the ground floor. You are asked to visit her, as she has had a funny turn and cannot seem to speak. Her daughter says she was well on waking, but became confused while being helped to the toilet and seems unable to stand unaided she normally walks with a Zimmer frame. Examination She is sitting in a chair, looking a little puzzled. She is unable to give a history, answering just yes to any question. She seems to be unwilling to use her arms or legs, although there is no evidence of pain or injury. There are no clear lateralizing neurological signs. Her pulse is 86 beats/minute, 11

12 somewhat irregular, and her blood pressure is 125/65 mmhg rather low for her. She has no carotid bruits. Questions What diagnoses should you consider? What are your options for her further care? What investigations might be helpful? Answer On a background of probable vascular dementia, she may have had a non-paralytic stroke. Her possible atrial fibrillation may have triggered a small thrombus into the brain. If the symptoms clear within 24 hours, it would be classified as a transient ischaemic attack (TIA). Or she could have a diabetic problem: hypo- or hyperglycaemia. Or her confusion might be a non-specific indicator of an occult urinary tract or respiratory infection. Using her glucose meter, you check her blood glucose and it is 6.7 mmol/l. You test the urine in her commode with a multistrip and this shows a trace of protein, some glucose, but no nitrites, leucocytes or blood. While this is going on she makes a gratifying recovery. She asks for a cup of tea, recognizes and begins to converse with her daughter and you, and after an interval is able to get up with assistance and walk a little with her frame. You explain to them that you think she has had a TIA. She is at risk of further episodes, and might suffer a full stroke. She could be admitted to hospital for more detailed investigation, such as a computed tomography (CT) scan, but she is reluctant to leave her comfortable home; her daughter is willing to continue caring for her and will monitor her progress. You would also consider a full workup for atrial fibrillation: ideally, this would require anticoagulation but in view of the danger of bleeding with warfarin given the history of frequent falls you decide to just add a prescription for aspirin and dipyridamole to her medication. You agree to revisit the next day, and arrange a care programme with the Community Team. Her Abbreviated Mental Test Score, measured later, is only 3 (where out of 10, 8 or more is normal and 7 or less significant). After discussion with her daughter you decide at this point not to refer her to a clinic to assess the use of a cholinesterase-inhibitor. The patient lives contentedly on for a further 2 years, before dying peacefully of a stroke at the age of

13 Key Points Full investigation of a probable stroke would require admission, but the logistics of this can be formidable for frail elderly patients: being taken out of familiar surroundings, away from the family, being shaken about in an ambulance, being interrogated, undressed, punctured and intubated by kindly but strange uniformed staff, can be profoundly disturbing experiences. Step back from the acute diagnosis and assess what is in the best interests of the whole patient. Using time to establish the natural history of an event is one of the most valuable resources for the GP. 13