Pathophysiology - 05 Nervous Disorders

• PATHOPHYSIOLOGY LECTURE 5 - DISEASES OF THE NERVOUS SYSTEM MENINGITIS • • Haemophilus influenzae meningitis: o leading cause of bacterial meningitis in children under 5 years of age. It occurs most frequently in children from 1 month up to 4 years with a peak at 6 to 9 months. o The infection usually spreads from somewhere in the respiratory tract to the bloodstream and then to the meninges (the membranes that cover the brain). At the meninges, the bacteria produce infection and inflammation causing serious illness and sometimes death o Symptoms ▪ Irritability, poor feeding in infants ▪ Fever (in young infants the temperature may actually be below normal) ▪ Severe headache (older children) ▪ Nausea and vomiting ▪ Stiff neck or pain in neck when flexed ▪ Pain in back when neck is flexed foreward and chin brought toward chest (older children) ▪ Unusual body posturing ▪ Photophobia o Complications ▪ Roughly 20% of patients may experience some hearing loss. ▪ Some patients will have brain damage, which can include seizures, mental retardation, hydrocephalus ("water on the brain"), learning disorders, abnormalities in speech and language development, and behavioral problems Meningococcal Menigitis: o infection caused by the bacterium Neisseria meningitidis that causes inflammation of the membranes covering the brain and spinal cord. o The death rate ranges from 5% to 15%, with young children and adults over 50 having the highest risk of death. o Symptoms: ▪ Rash, pinpoint red spots (petechiae) o Complications : ▪ Brain damage ▪ Shock ▪ Increased spinal fluid pressure ▪ Myocarditis (inflammation of the heart) ▪ Hydrocephalitis (blockage of spinal fluid in brain) ▪ Deafness ▪ Paralysis of various muscles ▪ Mental retardation Pneumococcal meningitis: o Streptococcus pneumoniae is the most common cause of meningitis in adults, and the second most common cause of meningitis in children older than 6 years old. o Prevention ▪ Early treatment of pneumonia and ear infections caused by pneumococcus may decrease the risk of meningitis. There are also two effective vaccines on the market to prevent pneumococcus infection. ▪ The current recommendations are for people at high risk for pneumonia, children, and everyone over the age of 55 to be vaccinated. o Treatment ▪ Antibiotic therapy should be started as soon as possible. Ceftriaxone is one of the most commonly used antibiotics. ▪ If antibiotic resistance is suspected, vancomycin or rifampin are used. o Prognosis ▪ With early treatment, the outcome is better. However, 20% of people who contract this disease will die of it and 50% have serious longterm complications LEPROSY • • • Alternative names: Hansen's disease o An infectious disease, known since Biblical times, which is characterized by disfiguring skin lesions, peripheral nerve damage, and progressive debilitation. Causes, incidence, and risk factors o Leprosy - caused by Mycobacterium leprae. o It is a difficult disease to transmit and has a long incubation period, which makes it difficult to determine where or when the disease was contracted. o Children are more susceptible than adults to contracting the disease. 2 common forms o tuberculoid and lepromatous, o Both forms produce lesions on the skin o lepromatous form is most severe, producing large disfiguring nodules. o All forms of the disease eventually cause peripheral neurological damage (nerve damage in the extremities) manifested by sensory loss in the skin and weakness of the muscles. o People with long-term leprosy may lose the use of their hands or feet due to repeated injury which results from absent sensation. o Leprosy is common in many countries in the world, and in temperate, tropical, and subtropical climates. o Approximately 100 cases per year are diagnosed in the United States. Most cases are limited to the South, California, Hawaii, and U.S. island possessions. o Effective medications exist, and isolation of victims in "leper colonies" is unnecessary. o The emergence of drug-resistant Mycobacterium leprae, as well as increased numbers of cases worldwide, have led to global concern about this disease. • • • • Symptoms: o one or more hypopigmented skin lesions that have decreased sensation to touch, heat, or pain o skin lesions that do not heal after several weeks to months o numbness or absent sensation in the hands and arms, or feet and legs o Muscle weakness resulting in signs such as foot drop (the toe drags when the foot is lifted to take a step) Treatment o Medications used to eliminate the microorganism and to reduce symptoms include: o Dapsone o Rifampin o Clofazimine o Ethionamide o Aspirin, prednisone, or thalidomide are used for the control of inflammation (e.g., "erythema nodosum leprosum") that may occur with therapy Expectations (prognosis) o Early recognition is important. Early treatment limits damage by the disease, renders the person noninfectious, and allows for a normal lifestyle. Complications o permanent nerve damage o cosmetic disfigurement • • o irritability o pain or stiffness of the back, arms, legs, abdomen o muscle tenderness and spasm in any area of the body o Neck pain o pain front part of neck o Neck stiffness o Back pain or backache o Leg pain (calf muscles) o Skin rash or lesion with pain o muscle stiffness Paralytic Poliomyelitis o fever, occurring 5 to 7 days before other symptoms o headache o stiff neck and back o Muscle weakness, asymmetrical o Abnormal sensations (but not loss of sensation) of an area o sensitivity to touch, mild touch may be painful o Difficulty beginning to urinate o constipation o Bloated feeling of abdomen o Swallowing difficulty o Muscle pain o Muscle contractions or muscle spasms, particularly in the calf, neck, or back o drooling o Breathing difficulty o irritability or poor temper control o positive Babinski’s reflex Treatment o The goal of treatment is to control symptoms while the infection runs its course. TETANUS • POLIO • • • Symptoms o There are three basic patterns of polio infection: subclinical infections, nonparalytic, and paralytic. o Most (95%) are subclinical infections, which may go unnoticed. o Clinical poliomyelitis affects the central nervous system (brain and spinal cord) and is divided into nonparalytic and paralytic forms. o It may occur after recovery from subclinical infection. Subclinical Infection: no symptoms, or symptoms lasting 72 hours or less o Slight fever o headache o general discomfort or uneasiness (malaise) o Sore throat o red throat o vomiting Nonparalytic Poliomyelitis o symptoms last 1 to 2 weeks o Moderate fever o headache o Stiff neck o vomiting o diarrhea o Excessive tiredness, fatigue • • A disease caused by the toxin of the bacterium Clostridium tetani that affects the central nervous system, sometimes resulting in death. o Infection begins when the spores are introduced into an injury or wound. o The spores germinate, releasing active bacteria that multiply and produce a neurotoxin, called tetanospasmin. o Tetanospasmin selectively blocks inhibitory nerve transmission from the spinal cord to the muscles, allowing the muscles to go into severe spasm. Prevention o Tetanus is completely preventable by active tetanus immunization (vaccine). o Tetanus immunizations are begun in infancy as a series of DPT shots (D = diptheria, P = pertussis or whooping cough, and T = tetanus). o Boosters are given to teenagers and older adults as Td shots (adult tetanus and diphtheria) or singly as just tetanus. o Immunization is considered to provide protection for ten years. o Studies in the army suggest that good protection persists up to 12 years after the last immunization. Symptoms o spasms and tightening of the jaw muscle (hence the name lockjaw) o Stiffening of the neck and other muscles o Spasms of the neck and other muscles o o • Stiffness of the chest muscles Stiffness of the abdominal muscles (abdominal stiffness) o Spasms and stiffness of the back muscles, often causing arching (opisthotinosis) o Tetanic seizures (painful, powerful bursts of muscle contraction) o Irritability o fever Treatment o Control and reverse the tetany with antitoxin, tetanus immune globulin. o Penicillin can be given to kill the Clostridium tetani; other antibiotics such as clindamycin, erythromycin, or metronidazole can be used in patients who are allergic to penicillin. o Remove and destroy the source of the toxin through surgical exploration and cleaning of the wound (debridement). o Treat symptoms with supportive therapy. o Muscle spasms can be treated with muscle relaxants such as diazepam. o Bedrest with a non-stimulating environment is also recommended (dim light, reduced noise, and stable temperature). o Sedation may be necessary to keep the affected person quiet. o Respiratory support with oxygen, endotracheal tube, and mechanical ventilation may be necessary. o • • BOTULISM • • • • • Signs and Symptoms: o Infant botulism is usually seen in children under 6 months of age. The children may receive medical attention because of symptoms such as constipation, poor sucking action, a weak cry, and a general, progressive muscle weakness. Description: o Infant botulism is caused by Clostridium bacteria that live in soil and dust. o These bacteria may also contaminate foods, especially honey. o Clostridium bacteria produce a toxin (poison) called botulinum toxin, which blocks the normal messages between muscles and nerves and affects muscles everywhere in the body. o The toxin usually affects intestinal muscles first. o Infant botulism occurs worldwide, and 98% of cases occur in infants between 1 to 6 months of age. o In the United States, most cases of infant botulism cannot be prevented, since the spores of Clostridium bacteria are found in soil everywhere. Duration: o Infants with infant botulism may require hospitalbased support for an extended period. o In severe cases of infant botulism, the child may require several weeks of hospitalization and even respiratory support. Contagiousness: o No special isolation or precautions are needed since this infection is not transmitted from person to person. Prevention: o Most cases of infant botulism cannot be prevented. • Parents can eliminate one risk factor by not feeding honey to children under age 1 year. Professional Treatment: o Doctors make the diagnosis of infant botulism by checking the infant's stool for Clostridium bacteria or Clostridium botulinum toxin. o A child with infant botulism is treated in a hospital, usually in an intensive care unit. Botox: o Botulinum toxin type A (BOTOX®) and botulinum toxin type B (MYOBLOC(™)) are purified substances derived from a bacteria that blocks the nerve signals from the brain to the muscle. By injecting very tiny amounts into a specific facial muscle, only the impulse of that muscle will be blocked, causing a local relaxation and weakness. o In this way, botulinum toxin acts as a muscle blockade to immobilize the underlying cause of the unwanted lines and prevent "wrinkly" expressions. o Botulinum toxin type A (BOTOX®) has been used since 1980 to treat many muscle disorders, such as lazy eye, and uncontrolled blinking. o It was pioneered by dermatologic surgeons for cosmetic use in 1987. o The FDA has granted approval to botulinum toxin type A (BOTOX® COSMETIC) for the temporary improvement in the appearance of moderate to severe glabellar vertical lines in adult men and women 65 or younger. o The approval specifically applies to the vertical lines between the eyebrows. Botulinum Toxin Therapy o Treatment involves injection of very small amounts of botulinum toxin into underlying muscles to relax them. o The actual treatment is well tolerated and takes just a few minutes with no "down time" or prolonged recovery period. o Botulinum toxin takes effect about 3 to 7 days after treatment. o Improvement generally lasts about 3-4 months before the effect gradually fades & muscle action returns. o It is anticipated that the average patient will require reinjection at various intervals. o With repeated treatments, atrophy (thinning) of the muscle may occur which usually produces longerlasting results. o Other Applications ▪ Excessive sweating can be treated with injections of a highly diluted form of botulinum toxin directly into the underarm skin, or skin on the palms of the hand and soles of the feet. ▪ There it paralyzes the sweat glands of the skin, which are responsible for excessive perspiration. ▪ A single treatment session can provide months of relief, and experts believe that injections can be repeated indefinitely once or twice a year to maintain dryness. o Are there any side effects? ▪ Side effects are minimal and typically relate to the local injection. ▪ Soreness or mild bruising, while uncommon, may occur around the injection site. ▪ ▪ ▪ ▪ Makeup may be worn after treatment, but care should be taken to avoid pressing or massaging the area for several hours. A temporary headache is not uncommon after injections in the forehead area, especially after the first treatment. In rare instances, patients may develop temporary weakness of the neighboring muscles, a temporary droopy brow or eyelid. All of these possible effects are likely to be mild and temporary, and in most cases, do not significantly limit routine activities. o o o o o o o o • RABIES • • • • • • • Fatal Encephalitis Caused by rabies virus Contracted through bite of infected animal o Bats, dogs, cats, rabbits, raccoons, Once virus enters nerves it is not accessible to immune system until destroys CNS cells Symptoms: o Preliminary symp. Are mild and varied ▪ Resemble many other infections o When CNS becomes involved person alternates between agitation and calm o Muscle spasms of mouth and pharynx 2 forms of rabies: o Furious rabies - restless, then become excitable and snap at anything ▪ Humans will sometimes bite too ▪ Paralysis sets in and flow of saliva increases ▪ Nervous control is progressively lost o Paralytic rabies - only minimal excitability ▪ Animal or person remains relatively quiet and unaware of surroundings ▪ A form of paralysis that is transient but sometimes fatal Treatment: injections or immunoglobulin and antirabies vaccine CRYPTOCOCCUS MENINIGITIS • • A rare fungal infection caused by inhaling the fungus, Cryptococcus neoformans Symptoms o Chest pain o Dry cough o Headache o nausea o confusion o Blurred vision or double vision (diplopia) o Fatigue o Fever o Unusual and excessive sweating at night o Glands, swollen WITHOUT nearby areas appearing infected (e.g., red, painful, swollen) o Prolonged bleeding, bruising easily o Skin rash may be present o Skin rash or lesion pinpointed rash (petechiae) o Bleeding into the skin o Bruises o Unintentional weight loss o Appetite, loss • Abdominal fullness prematurely after meals Abdominal pain Abdomen, swollen Weakness Bone pain or tenderness of the breastbone (sternum) Numbness and tingling Nerve pain or pain along the path of a specific nerve Pain along a nerve root (major pathway from the spinal cord Treatment o Some infections require no treatment. However, medical observation should continue for a year to detect any progression of the disease. If pulmonary lesions are present or the disease spreads, antifungal medications are prescribed, and treatment with these agents may be prolonged. o Medications include: ▪ Amphotericin B ▪ Flucytosine ▪ Fluconazole