Pathology 8 Flashcards
Scarlet fever
Scarlet fever is an exotoxin-mediated disease arising from a specific bacterial infection by an erythrogenic (causing inflammation and reddening of the skin) toxin-producing strain of Streptococcus pyogenes
Pathophysiology
•In most cases scarlet fever evolves from a tonsillar or pharyngeal infection
•Person-to-person spread is mainly by respiratory droplets. The incubation is typically 2 to 5 days but ranges from 1 to 7 days.
•Patients are contagious both during the acute illness and the initial subclinical stage
Epidemiology
• 87% children are aged under 10 years with a median age of 4 years. Scarlet fever is unusual under the age of 2 years because of maternal antibodies to the exotoxin and lack of prior sensitisation.
•The infection rate increases with overcrowding and close contact. School populations have a higher incidence
•Incidence decreases in adults as immunity develops.
Scarlet fever management
Treatment
•Antibiotics. Penicillin or azithromycin if penicillin-allergic are the treatments of choice given for a full 10 days.
Signs of meningitis
Signs and symptoms of may include: ◾Fever ◾Headache ◾Nausea ◾Vomiting ◾Sleepiness ◾Irritability ◾Stiff neck ◾Seizures ◾Photophobia CLASSIC TRIAD •Bulging fontanelle (in infants) •Altered mental state, unconsciousness, toxic/moribund state. •Unusual skin colour, capillary refill time more than 2 seconds; cold hands/feet. •Tachycardia and/or hypotension; respiratory symptoms or breathing difficulty. •Leg pain •Poor urine output •Haemorrhagic rash (a type of rash caused by bleeding underneath the skin)
Signs
•Kernig’s sign (pain and resistance on passive knee extension with hips fully flexed).
•Brudziñski’s sign (hips flex on bending the head forward).
Timing of symptoms
• Classical signs such as haemorrhagic rash, the triad and impaired consciousness did not tend to appear until after 13 to 22 hours.
•More nonspecific features such as leg pain, cold hands and feet and abnormal skin colour appeared much earlier with a median onset of 7-12 hours.
•These earlier features are therefore very important in early diagnosis and therefore in the earlier initiation of potentially life-saving treatment
APGAR score
This is the first test given to newborns after birth.
- Used to assess the condition of the newborn.
- Usually done at 1 and 5 minutes after birth. However, if there is still some concern then it maybe repeated after 10 minutes.
- APGAR is an acronym that stands for: Appearance, Pulse >100, Grimace?, Activity and Respiration.
Appearance: Is the look of the baby, especially noting the colour of the baby’s skin. This is a good indicator of how good a baby’s circulation is.
Pulse: Is the Heart rate of the newborn.
Grimace: Is how the baby reacts to stimulation. This stimulation is usually a pinch on the arm or a rub on the sternum (chest wall) to stimulate mild pain.
Activity: This is how much the baby is moving and general muscle tone
Respiration: Is not only how fast a baby is breathing but also how much effort the baby is putting in and how regular the breathing is. A baby’s cry is a very good indicator of how well the baby is breathing.
score from 0-2 for each category out of ten together. 7-9 is normal.
Measles incubation period and development
-Incubation period is between 8-14 days. An incubation period is the time period between first coming into contact with the pathogen and the pathogen causing symptoms.
The clinical features of measles can be split into a pre eruptive and eruptive stage (Basically a stage before the rash and a stage once the rash has developed).
Pre-eruptive: Malaise, fever, runny nose, cough and conjunctivitis (Redness and irritation of the eyes). During this acute illness there are many viruses being shed and spread in the droplets so the person is most infective during this period.
A more diagnostic sign is the appearance of koplik’s spots. These are greyish spots that appear on the buccal membrane (on the cheek) a say or two after the flu-like symptoms and a day or two before the rash appears.
Eruptive: The rash usually appears 3-4 days after the general symptoms.
The rash begins on the face usually on the forehead (or below the hairline, depending which sources you believe) and then spreads down the rest of the body.
The rash is maculopapular in nature. The rash is characterized by flat, red areas on the skin covered by confluent bumps.
The rash usually fades after a week, but may leave some scaring towards the end in severe cases.
School exclusion: children with measles should be kept out of school and isolated as much as possible for at least 5 days after the rash begins.
Mumps complication
Complications: In pre-pubertal males the virus can cause Orchiditis (inflammation of the testes). The most severe complication occurs if the virus enters the meninges (protective layer over spinal cord/brain), causing meningitis; this occurs in about 5% of cases.
Rubella presentation
-Incubation period varies from 2-3 weeks.
Pre-eruptive: Malaise, fever, lymphadenopathy and mild conjunctivitis. Virus isn’t yet having a huge systemic impact.
Eruptive phase: Symptoms develop to become body wide potentially affecting multiple systems. This includes arthralgia and arthritis if the virus enters the joints, crossing the placenta and damaging the foetus if it occurs in the pregnant woman and finally the skin rash. This usually starts on the face and spreads rapidly to the body. A key difference between Rubella and Measles rashes is that Rubella fades after about 3 days. The rubella rash is usually red, macular and discrete.
TORCH Infection of pregnancy:
T: Toxoplasmosis O: Other R: Rubella C: Cytomegalovirus H: Herpes Simplex Virus – 2
Other diseases:
- HIV
- Varicella-Zoster virus (Chicken pox)
- Hepatitis B
- Parvovirus B19 (Slapped cheek syndrome)
- Toxoplasma gondii (Syphilis)
- Listeria monocytogenes (Listeriosis)
- Mycobacterium leprae (Leprosy)
Unusual fracture types
Pott- a fracture of the distal (situated away from the centre of the body) end of the fibula, with serious injury of the distal tibial articulation
Colles- a fracture in which the distal end of the radius in which the distal fragment is displaced forward
Stress- is a fatigue-induced fracture of the bone caused by repeated stress over time.
Instead of resulting from a single severe impact, stress fractures are the result of accumulated trauma from repeated submaximal loading, such as running or jumping. Because of this mechanism, stress fractures are common overuse injuries in athletes.
Stress fractures can be described as a very small sliver or crack in the bone; and are sometimes referred to as “hairline fractures”.
Lower limb palsies
Femoral Nerve dysfunction-
• Weak or unable to flex the hip of extend the knee
• Sensation loss on the anterior and medial aspect of the thigh and the medial side of the leg and foot
Obturator Nerve dysfunction-
• Weak or unable to abduct at the hip
• Sensation loss over the medial aspect of the thigh
Tarsal tunnel syndrome-
This is a condition where the tibial nerve is compressed within the tarsal tunnel (posterior to the medial malleolus). There are varying causes, of which the main three are:
• Osteoarthritis
• Rheumatoid arthritis
• Post-trauma ankle deformities
Patients complain of paraesthesia in the ankle and sole of the foot, which can radiate up the leg slightly. It is aggravated by activity and relieved by rest.
Tarsal tunnel symptoms can be treated conservatively by anti-inflammatory drugs and changes in footwear. If these interventions are not successful, the flexor retinaculum can be cut surgically, which releases the pressure.
Tibial Nerve dysfunction
Damage to the tibial nerve is rare, and is often a result of direct trauma, entrapment through narrow space or compression for long period of time.
• Damage results in loss of plantar flexion, loss of flexion of toes
• Sensation loss on the posterolateral skin surface of the lower leg and all the planter surface of the foot apart from a small section of the medial aspect
Common Fibular Nerve dysfunction-
The common fibular nerve is most commonly damaged by a fracture of the fibula, or the use of a tight plaster cast. The anatomical course of the common fibular nerve causes it to wrap round the neck of the fibular, and so any fractures of the fibular neck can cause nerve palsy.
• Patients with common fibular nerve damage will lose the ability to dorsiflex the foot at the ankle joint. Hence the foot will appear permanently plantar flexed – known as foot drop
Loss of sensation on-
• Lateral aspect of the knee and lower limb
• Dorsal aspect of the foot
• Posteromedial aspect of the planter surface of the foot
Causes of ABG change
Causes of metabolic acidosis
• Lactic acidosis: shock, infection, hypoxia.
•Urate (renal failure).
•Ketones (diabetes mellitus, alcohol).
•Diarrhoea.
•Addison’s disease.
•Drugs or toxins: acetazolamide, ammonium chloride.
Causes of metabolic alkalosis •Vomiting. •Hypokalaemia - eg, diuretics •Excessive alkali drugs, such as for acid dyspepsia. •Burns.
Causes of respiratory acidosis
Acute:
•Depression of the central respiratory centre by cerebrovascular disease or drugs.
•Inability to ventilate adequately due to neuromuscular disease - e.g. myasthenia gravis, amyotrophic lateral sclerosis, Guillain-Barré syndrome, muscular dystrophy.
•Airway obstruction related to asthma or exacerbation of chronic obstructive pulmonary disease (COPD).
Chronic:
•Chronic respiratory acidosis may be secondary to many disorders – e.g. COPD, obesity hypoventilation syndrome
Causes of respiratory alkalosis
Respiratory alkalosis results from hyperventilation - eg, anxiety, stroke, meningitis, altitude, pregnancy
Down’s syndrome Trisomy 21
Facial-
•An oval-shaped face.
•Eyes that slant upwards
•A small mouth and a tongue that often protrudes.
•The back of their head (called the occiput) is often flatter than normal.
•Their nose may be small and have a flat and low bridge.
•Ears may also be small and low-set
Other physical features
•Short fingers and a little finger that can curve inwards.
•Muscles that lack tone and can be quite floppy (this is often most noticeable in babies).
•Babies may have a low birth weight.
Mental Retardation
Everyone with Down’s syndrome will have some degree of learning difficulty, however the severity varies from person to person
Other
•90% of patients with Down’s syndrome will have some sort of hearing loss
Around half of babies with Down’s syndrome will have a congenital heart defect, especially atrioventricular septal defect (AVSD).
Women who are at high risk of having a child with downs syndrome are offered diagnostic testing using either chorionic villus sampling (if less than 13 weeks of gestation) or amniocentesis (if beyond 15 weeks of gestation). These procedures carry a risk of miscarriage (0.5-1% excess miscarriage risk for amniocentesis; 1-2% for chorionic villus sampling).
Edwards Syndrome (Trisomy 18)
Features
Signs of Edwards’ syndrome include:
•a small, abnormally shaped head
•a small jaw and mouth (micrognathia)
•long fingers that overlap, with short fingernails and clenched fists
•low-set ears
•smooth ‘rocker bottom’ feet (convex bottom of feet)
•heart and kidney problems
•feeding problems in infancy, leading to poor growth
•breathing problems
•hernias
•bone abnormalities, such as a curved spine
•frequent infections of the lungs and urinary system
•a severe learning disability
•New-borns have a 40% chance of surviving to age 1 month.
Patau’s Syndrome (trisomy 13)
Features
Many foetuses never survive until term and are stillborn or spontaneously abort.
Signs of Trisomy 13-
•Intrauterine growth restriction and low birth weight.
•Congenital heart defects: these occur in 80%
•Cleft lip and palate.
•Nasal malformation.
•Hypotelorism (reduced distance between the eyes) or cyclops.
•Severe learning disability.
•Problems with control of breathing
•Polydactyly (a condition in which a person or animal has more than five fingers or toes on one, or on each, hand or foot)
•Rocker-bottom feet
•Ear malformations and deafness.
•hernias
Tend to die within days. Maternal age is less influential.
Turners Syndrome 45X
•Webbed Neck (KEY SIGN) •Short Stature •Normal IQ •Primary amenorrhoea and Infertility (due to sex hormones oestrogen and progesterone not being produced) •Broad chest and widely spaced nipples Patients with Turners syndrome are at an increased risk of chronic condition such as- •Crohn's disease. •Coeliac disease. •Hashimoto's thyroiditis •Hypertension •Type 1 diabetes mellitus •Lymphoedema
Klinefelter’s Syndrome 47XXY
Clinical Features
•Infertility
•Small firm testes; decreased facial and pubic hair; loss of libido
•Tall and slender, with long legs, narrow shoulders, and wide hips.
•Gynaecomastia or history of gynaecomastia during puberty; decreased libido; history of undescended testes.
•Learning disability; delayed speech development; behavioural problems; psychosocial disturbances.
•Other features may include tiredness, reduced muscle power and stamina, and truncal obesity
Management
Testosterone replacement
This reduces the risks of most of the long-term complications associated with Klinefelter’s syndrome
•Treatment should begin as they enter puberty.
•XXY males diagnosed in adulthood are also likely to benefit from the hormone.
•A regular schedule of testosterone injections will increase strength and muscle size and promote the growth of facial and body hair.
Prognosis
Increased risk of; breast cancer, osteoporosis, hypothyroidism, diabetes mellitus, etc.
However, overall the lifespan of a male with Klinefelter’s syndrome is normal
•It is the most common sex chromosome disorder, affecting 1 in 660 men
The Abortion Act 1967
The Abortion Act 1967 covers England, Scotland and Wales
Normal- 2 Doctors- Before 24 weeks
•abortions must be carried out in a hospital or a specialist licensed clinic
•two doctors must agree that an abortion would cause less damage to a woman’s physical or mental health than continuing with the pregnancy
There are also a number of rarer situations when the law states an abortion may be carried out after 24 weeks. These include:
Emergency- 1 Doctor- Anytime
•if it’s necessary to save the woman’s life
•to prevent grave permanent injury to the physical or mental health of the pregnant woman
Genetic Abnormality- 2 Doctors- Anytime
•if there is substantial risk that the child would be born with serious physical or mental disabilities
Spina Bifida
Spina Bifida Occulta: Least severe form. The incomplete fusion is minor and causes very few problems
Meningocele: A cyst pushes through the vertebrae that aren’t fused completely. This cyst contains no nervous tissue, only the meninges*.
Myelomeningocele: A cyst forms through the gap between vertebrae. The cyst contains the spinal cord itself; this is the most severe form with a poor prognosis.
-If a cyst is present the condition is called Spina Bifida Cystica; Meningocele and Myelomeningocele are sub-types of Spina Bifida Cystica.
Myelomeningocele
Raised, red cyst Have TCS: Lower limb weakness Fecal/urinary incontinence Impaired sensation
Spina Bifida Occulta Normal, or Skin Dimple Tuft of hair Usually asymptomatic Don’t know they have it Maybe mild back pain
Meningocele
Raised, red cyst
Often asymptomatic
May have tethered spinal cord syndrome
(TCS)
The 3 cardiac shunts
- The Ductus Venousus limits the amount of blood that initially enters the liver instead channeling it towards the Inferior Vena Cava
- The Foramen Ovale allows most blood to directly enter the left atrium from the right atrium. This allows blood to reach systemic circulation faster.
- The Ductus Arteriousus allows blood from the pulmonary arteries into the aorta. This reduces the amount of blood going to the lungs and increases the amount of blood available for the brain and rest of the body.
