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Showing posts with label MRCP revision. Show all posts

Drug Induced Liver Injury

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Drug-induced liver injury (DILI) can present as cholestasis, hepatitis or as a mixed picture.  DILI can be either dose-related (eg with paracetamol) or idiosyncratic.   A cholestatic picture of DILI is more common in older patients while a pattern of hepatocellular damage is more common in younger patients.

 A persons susceptibility to idiosyncratic DILI is a mixture of genetic predisposition, age, gender (females more susceptible), existing medical conditions (eg diabetes increases severity) and immune factors.

DILI is clinically significant both because it is the leading cause of acute liver injury and also because it is the leading cause of aborted development or withdrawal of otherwise promising drugs.

 Drugs associated with DILI include:
- anti HIV agents
- antibiotics  (penicillins - esp co-amoxiclav, macrolides, isoniazid)
- CNS agents (phenytoin, carbamazepine,  sodium valproate, gabapentin, risperidone, tricyclic antidepressants)
- analgesics (NSAIDs, paracetamol)
- antihypertensives (ACE-inhibitors)
- antiglycaemics (metformin, pioglitazone)
- others (atorvastatin, herbal health supplements)

Management:
- stop precipitating drug
- supportive management
- ? n-acetylecysteine

 Most patients recover fully from DILI once the offending drug is withdrawn but a small number develop chronic liver disease.





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Ulnar nerve palsy for PACES

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There is wasting of the dorsal interossei causing dorsal 'guttering'.
There is wasting of the hypothenar eminence.
There is clawing of the 4th and 5th digits.
There is sensory loss over the medial 1.5 digits and corresponding part of the hand which does not extend proximal to the wrist.
Froments sign is present.


What causes do you know for an ulnar nerve palsy?
  • can be a lesion at any point from brachial plexus to the hand
  • compression: any mass at the elbow (eg boney mass in RA or OA, soft tissue mass), post operative or ITU stay
  • trauma (especially at medial epicondyle)
  • any cause of a mononeuropathy: diabetes, vasculititides (PAN, Wegeners), leprosy, amyloidosis...


What is the root of the ulnar nerve?
C8 and T1 


What do you mean by 'claw hand'?
Flexion of the interphalangeal joints and hyperextension of the metacarpophalangeal joints.


What is the function of the dorsal interossei?
Abduction of the fingers (recall D-AB and P-AD: dorsal abduction, palmar adduct)


What does the hypothenar eminence consist of?
Oppenes digiti minimi, Abductor digiti minimi and Flexor digiti minimi  
What muscles are innervated by the ulnar nerve?
  • C8: flexor carpi ulnaris, flexor digitorum profundus and superficialis to the ring and little fingers
  • T1: All intrinsic muscles of the hand except for the lateral 2 lumbicals, oppenens pollicis brevis, abductor pollicis brevis and flexor pollicis brevis (LOAF), which are innervated by the median nerve.


How can you tell a 'low' ulnar lesion from a 'high' lesion?
  • In a low lesion there is partial clawing of the hand as the lumbricals of the ring and little finger are paralysed causing MCP hyperextension whilst the flexor digitorum profundus is intact and causes DIP flexion.  Low lesions occur at the wrist.
  • In a high lesion the flexor digitorum pronfundus is also paralysed so the DIPs are not flexed, making the clawing less obvious.  High lesions usually occur at the elbow.

What is Froment's sign?
This is when the ulnar nerve is damaged so the adductor pollicis is paralysed, meaning that when a piece of paper is held between the thumbs and index fingers and pulled the paralysed thumb flexes.

What alternative diagnosis for a claw hand do you know?
  • Diabetic cheiropathy
  • Ischaemic contracture 

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Interstitial Lung Disease

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Interstitial lung disease describes a group of lung diseases which affect the lung interstitium (= the tissue of the alveolar wall between the capillary endothelium and the alveolar epithelium) and share similar clinical and radiological features.

Diffuse parenchymal lung disease is synonymous with interstitial lung disease.


In 2002 the European Respiratory Society and American Thoracic Society produced the following classification of interstitial lung diseases:

  • ILD of known cause or association
    • Environmental - eg bird exposure
    • Occupational - eg silicosis, asbestosis
    • Drug-associated - eg amiodarone, methotrexate, cyclophosphamide, nitrofurantoin
  • ILD of unknown cause 
    • Idiopathic interstitial pnuemonias
      • Idiopathic pulmonary fibrosis (previously known as crytogenic fibrosing alveolitis)
      • IIP other than IPF eg crytogenic organising pneumonia,
    • ILD associated with connective tissue diseases eg RA, scleroderma, polymyositis
    • Granulomatous ILD eg sarcoidosis
    • Other forms, eg histiocytosis X, eosinophilic pneumonias


Presentation tends to be:
  • progressive breathlessness with exercise
  • persistent non-productive cough


Investigations:
  • CXR - may be normal; may show increased reticular markings, ground glass abnormalities or nodular opacities
  • HRCT 
    • honeycombing - pulmonary fibrosis
    • ground glass changes - hypersensitivity pneumonitis
    • distribution of changes can also help diagnosis
  • lung function tests 
    • most commonly show a restrictive pattern with decreased lung volume and diffusing capacity for carbon monoxide
    • however patterns can vary
  • bronchoscopy
    • can help exclude infections
    • transbronchial biopsies - may diagnose sarcoidosis/hypersensitivity pnuemonitis
  • surgical biopsy
    • most commonly via VATS (video-assisted thoracic surgery)


Management
  • pulmonary rehabilition
  • smoking cessation
  • ? oxygen therapy
  • details depend on the type of interstitial lung disease, for example:
    • idiopathic pulmonary fibrosis - ?  N-acetylecysteine
    • sarcoidosis - ?prednisolone if pulmonary function badly affected
    • hypersensitivity pneumonitis - avoidance of allergen


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Alcoholic hepatitis

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Alcoholic hepatitis is a clinical syndrome characterised by recent onset of jaundice and/or ascites in a patient with ongoing alcohol misuse.

The predominant cause of alcoholic hepatitis is alcoholic steatohepatitis, which is diagnosed histologically by the presence of steatosis, hepatocyte ballooning and inflammatory infiltrate with PMNs.

Presentation may include:
  • progressive jaundice
  • ascites
  • fever 
  • weight loss
  • hepatolomegaly
  • anorexia
  • nausea and vomiting
  • abdominal pain

Investigations:
  • LFTs
    • AST typically 2-6x upper limit of normal
    • AST/ALT ratio >2
    • bilirubin frequently raised
  • clotting
  • FBC
  • screen for HBV, HCV, HIV
  • abdominal US to exclude other causes of jaundice
  • consider transjugular liver biopsy

Several scoring systems exist to assess prognosis (Maddrey's discriminant function, MELD, ABIC, Glasgow).  Maddrey's is the commonest:

Maddrey discriminant factor = (4.6 x prolongation of PT) + serum bilirubin (mg/dl) 
(NB in UK bili is given in micromol/l so needs to be divided by 17)

>32 indicates poor outcome.

Management of high-risk patients:
  • prednisolone 40mg OD 
    • or pentoxifylline (a phosphodiesterase inhibitor and TNF alpha inhibitor) 400mg TDS if patient septic
  • ? enteral feeding
  • ? n-acetylcysteine in patients with severe disease receiving steroids
  • careful monitoring of renal function  
  • careful watching for infection and prompt treatment if present

Complications
  • GI bleeds requiring transfusion occur in around 20%
  • encephalopathy occurs in around 20%
  • hepatorenal syndrome


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Sturge-Weber Syndrome

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Sturge-Weber Syndrome is the association of a port-wine haemangioma in the trigeminal nerve distribution area (predominantly the opthalmic branch) with a vascular malformation of the brain.

Possible associated features include:
  • glaucoma
  • epilepsy
  • mental retardation
  • hemiparesis
Management may include neurosurgery.


However, it is worth noting than only around 3% of patients with a facial port-wine stain have Sturge-Weber syndrome.

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Primary Sclerosing Cholangitis

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Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease, likely autoimmune.

It most commonly affects men (3:1) and mean age of diagnosis is 40.

At presentation up to 55% of patients are asymptomatic.  Possible symptoms include:
  • pruritis
  • fatigue
  • abdominal pain
  • jaundice
Investigations:
  • LFTs - raised ALP, mild to moderate increases in AST/ALT
  • Autoantibodies
    • ANCA positive in 80% - but not specific
    • ANA - 20-60%, again not specific
    • SMA - 20-60%, not specific
    • (AMA is rarely positive - far more associated with PBC)
  • MRCP - gold standard
  • ERCP
    • shows strictures of biliary tree with characteristic 'beaded' appearence
  • Liver biopsy
    • not necessarily helpful
    • may reveal concentric periductal fibrosis (='onion skinning')

Complications
  • cholangiocarcinoma - up to 30%
  • colorectal cancer

Associations:
  • 80% of patients with PSC have ulcerative colitis (although only 4% of patients with UC have PSC)
  • 7-50% of patients with PSC also have autoimmune hepatitis
Treatment:
  • ursodeoxycholic acid
  • colestyramine or rifampicin for pruritus
  • liver transplant
    • but up to 40% recurrence of PSC in organ
    • median time from diagnosis to transplant needed: 18 years
  • ERCP to stent strictures
  • (yearly colonoscopy if UC)

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Acute promyelocytic leukaemia

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Acute promyelocytic leukaemia is the M3 subtype of AML

Features include:
  • translocation t(15;17) that produces the PML-RARα gene
  • bundles of auer rods (=faggots) 

It predisposes to DIC, but as long as this is treated its prognosis is good with treatment with all trans retinoic acid or arsenic trioxide.

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Renal cell carcinoma

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The classic presentation of renal cell carcinoma (hypernephroma) is the triad of
  • flank pain
  • haematuria
  • flank mass
However, just 10% of patients with RCC present with these symptoms and 40% have none of them at all!

Other presentations include:
  • weight loss (30%)
  • fever (20%)
  • hypertension (20%)
  • hypercalcaemia (5%) 

Occasionally they may be associated with a left varicocele.
Renal cell carcinomas may also produce erythropoeitin, resulting in secondary polycythaemia.

Most RCC are sporadic; a minority are familial, for example associated with Von Hippel Lindau.

Treatment is surgical.


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Angioid Retinal Streaks

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Angioid retinal streaks are caused by breaks in Bruch's membrane.

Conditions associated with angioid retinal streaks include:

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Autoimmune hepatitis

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Autoimmune hepatitis is a chronic inflammatory liver disease which, untreated, often leads to cirrhosis.

 Presentation
  • 25% asymptomatic at diagnosis
  • Others:
    • fatigue
    • pruritis
    • anorexia
    • nausea
    • abdominal pain
    • joint pain

Associations
  • long-term use of some medications, such as nitrofurantoin or minocycline
  • primary biliary cirrhosis - up to 15%
  • primary sclerosing cholangitis - up to 8%
  • thyroiditis - up to 23%
  • diabetes - up to 9%

Investigations
  • LFTs - raised AST/ALT
  • autoantibodies
    • ANA
    • SMA
    • SLA/LP (soluble liver antigen/liver-pancreas)
    • LKM (liver-kidney microsome)
    • dsDNA - 15% (specific for either AIH or SLE)
  • raised IgG
  • negative tests for viral hepatitis
  • liver biopsy may show
    • lots of plasma cells - 'plasma-cell hepatitis'
    • inflammation of hepatocytes at the junction of portal tract and hepatic parenchyma - 'piecemeal necrosis'

Types of AIH:
  • Type 1
    • 75% of AIH
    • ANA/SMA/anti SLA/LP
    • all ages
    • F:M 3:1
  • Type 2
    • anti-LKM-1 or anti LC-1
    • usually presents in childhood
    • F:M 10:1
    • more likely to not respond to treatment
Treatment
  • corticosteroids
  • azathioprine
  • lifelong in type 2 AIH; can consider stopping after remission of at least 4 years in type 1 AIH 
  • 10-20% of patients will need liver transplants.

Small print gems: In terms of liver diseases, raised IgG suggests AIH, IgM suggests PBC and IgA suggests steatohepatitis (alcoholic or non-alcoholic)


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IgA Nephropathy

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IgA nephropathy, also known as Berger's disease, is the commonest glomerulonephritis.

The classical patient is a young man with haematuria after an upper respiratory tract infection.

Overall micro or macrohaematuria is the presenting feature in around 40% of cases.

Histologically there is mesangial hyperplasia and on immunofluorescence there is IgA and C3 deposition.

It is often a subclinical condition, but amongst those for whom it becomes clinically apparent there is around 20% progression to end stage renal failure at 20 years.

A poorer prognosis is associated with
  • male gender (the majority of sufferers are male)
  • proteinuria
  • obesity 

Associated conditions include

Management
  • Angiotensin 2 inhibitor or ACE-i
  • if this fails, ?immunosupression
  • in renal failure consider transplant, although IgA nephropathy recurs in the majority of grafts

 Henoch Schonlein Purpura is sometimes regarded as the systemic manifestation of IgA nephropathy.

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Membranous glomerulonephritis

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Membranous glomerulonephritis is usually regarded as the commonest cause of nephrotic syndrome in the western world (although focal segmental glomerulonephritis is sometimes now regarded to have overtaken it.)

It is characterised by a thickened basement membrane on microscopy and IgG and C3 deposits on immunofluorescence. 

It may be primary or secondary to:
  • drugs
    • captopril
    • NSAIDs
    • penicillamine
    • gold
    • clopidogrel
  • mercury
  • infections
    • HBV
    • HCV
    • malaria
    • schistosomiasis
    • TB
  • cancer
  • autoimmune conditions

Treatment
  • management depends on the risk of progression
    • low risk patients are managed conservatively (BP control and ACE-i)
    • higher risk patients are given corticosteroids and cyclophosphamide

Prognosis
  • a third remit spontaneously
  • the remainder either develop persistent proteinuria or progress to chronic renal failure


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Focal segmental glomerulonephritis

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Focal segmental glomerulonephritis is the commonest cause of nephrotic syndrome in afro-american adults.

Histologically there are focal areas of sclerosis and on immunofluorescence there is IgM and C3 deposition.

Focal segmental glomerulonephritis may be primary or secondary to:
  • reflux nephropathy
  • obesity
  • Alport's syndrome
  • sickle cell disease
  • HIV
  • heroin use
  • IgA nephropathy

Treatment is:
  • corticosteroids
  • if steroids fail, ? ciclosporin
  • if all fails, kidney transplant
    • but note that focal segmental glomerulonephritis can recur in the transplanted kidney

Prognosis
  • around a third of patients respond to steroid treatment and recover
  • around 50% progress to end-stage renal failure



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Contrast radiology

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There are 3 main risks associated with using contrast:

1) Allergic reactions
  • Reactions occur in 0.15% of cases.  These are classified as 'severe' in just 0.04% of cases.
  • Allergic reactions are 6 to 10 times more common in asthmatics; non ionic low or iso-osmolar agents should be used for these patients.

2) Contrast nephropathy
  • This is defined as an impairment in renal function (an increase in serum creatinine by more than 25% or 44micromol/l) within 3 days of administration of IV contrast in the absence of an alternative aetiology
  • Risk of contrast nephropathy is increased in patients with:
    • eGFR <60
    • dehydration
    • CCF
    • gout
    • age >70
    • concurrent use of nephrotoxic drugs, eg NSAIDs or gentamycin
  • The risk of contrast nephropathy can be reduced by:
    • using the smallest possible dose of contrast
    • ensuring the patient is well hydrated before and after the procedure either orally or, if the contrast is to be given arterially or at high dose, by IV fluids
    • there is currently insufficient evidence to support the use of n-acetyl cysteine in prevention of contrast-induced nephropathy
  • There is no need for metformin to be stopped routinely for contrast investigations as long as the eGFR is >60.  If it is below this level, stopping for 48 hrs before and after the investigation should be considered.

3) Extravasation
  • Conservative management is sufficient in most cases - elevate limb and apply ice packs.
  • Plastic surgeon input may occassionally be required.

Other points:
  • Contrast can be used in breastfeeding mums with no special precautions.
  • Contrast cannot be used in patients who are hyperthyroid.
  • There is a specific risk of a delayed skin rash if contrast is given to patients on interleukin-2 therapy.




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Status epilepticus

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Status epilepticus is a prolonged seizure, usually defined as >30 minutes.

Over half of patients presenting with status epilepticus do not have known epilepsy.

The main acute causes in adults are:
  • stroke
  • hypoxia
  • metabolic derangement
  • alcohol intoxication or withdraw
In children, the leading cause is infection.

Management:
  • secure airway and resuscitate
  • give oxygen
  • anti-epileptics:
    • pre-hospital: diazepam 10-20mg PR or midazolam 10mg buccally
    • first line in hospital: lorazepam (or diazepam) IV
      • terminates around 75-80% of seizures
    • if benzo unsuccessful: phenytoin infusion 15-18mg/kg at a rate of 50mg/minute 
      • will terminate around 50% of resistant seizures
  • if any suggestion of alcohol abuse or impaired nutrition give 50mls of 50% glucose and/or 250mg IV thiamine
  • if status is refractory (ie not resolved 60-90 minutes after initial anti-epileptic) anaesthetise using propofol, midazolam or thiopental sodium.

Prognosis: mortality of 10-20% rising to nearly 50% in refractory status epilepticus. 


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Yaws

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Yaws is a tropical disease of the skin caused by treponema pallidum subspecies pertunue.

It is spread by direct skin contact with an infected person or insect bite.

Yaws presents as:
  • an initial papule/papilloma that may persist for 3-6 months
  • if untreated, a late stage with multiple lesions, disfigurement of nose and bones and palmar/plantar hyperkeratosis.

Diagnosis is by dark light microscopy, rapid plasma reagin (RPR) or VDRL.  Note that it and syphilis give the same positives due to the close relationship of the causative organism.

Treatment is a single IM injection of benzylpenicillin.

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McArdle's disease

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McArdle's disease is a type V glycogen storage disease caused by a deficiency of glycogen phosphorylase in muscle.  It is characterised by:
  • muscle cramps on exertion
  • dark urine due to myoglobin
  • absence of normal rise in serum lactate on exertion

Ingestion of sucrose during exercise may help improve symptoms.

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Driving rules UK

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Key excerpts from the DVLA website (updated Sept 2012)

Rules:
  • First unprovoked epileptic seizure/solitary fit (all attacks within one 24 hour period are treated as a 'single event') : 6 months off driving unless clinical factors suggest an unacceptably high risk of a further seizure.  For bus/lorry drivers: 5 years off.
  • Known epilepsy: can drive whilst seizure free but:
    • if a known epileptic has a seizure:
      • during the day: 1 year off driving
      • during the night: 1 year off driving unless they have had a seizure whilst asleep more than 3 years previously and no daytime attacks, in which case they may continue driving.
    • cannot drive bus/lorry until off medication AND seizure free for 10 years
  • Solitary loss of consciousness likely to be cardiac in origin (but excluding vasovagal collapses): 6 months off if no cause identified. 4 weeks off if cause identified and treated.
  • TIA: no need to notify DVLA but must not drive for 1 month. For bus/lorry drivers: 1 year off.
  • Stroke: must not drive for 1 month and may resume driving afterwards if satisfactory clinical recovery. For bus/lorry drivers: 1 year off.
  • Unstable angina: must cease driving until symptoms controlled. No need to inform DVLA
  • ACS: - no need to notify DVLA
    • successfully treated by angio: can drive after 1 week as long as LVEF at least 40%
    • can drive after 4 weeks if not successfully treated by angio
    • if bus/lorry driver: at least 6 weeks off
  • Elective PCI: no driving for 1 week. (6 weeks bus/lorry driver)  No need to notify DVLA
  • CABG: no driving for 4 weeks, 3 months if bus/lorry driver.
  • Pacemaker implant, including box change: no driving for 1 week (6 weeks for bus/lorry)

GMC advice: "if you do not manage to persuade the patient to stop driving, or you discover that they are driving against your advice you should contact the DVLA immediately and disclose any relevant medical information, in confidence, to the medical advisor. Before contacting the DVLA you should try to inform the patient of your decision to disclose personal information. You should then also inform the patient in writing once you have done so"



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Mediterranean Spotted Fever

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Mediterranean spotted fever is a tick-borne disease caused by rickettsia conorii, a gram negative, obligate intracellular bacteria.

It is endemic around the Mediterranean.

Symptoms begin within 6 to 10 days of the tick bite:
  • typical rash - a black crusted eshchar (tache noir) at site of tick bite then a macular rash that typically spares the face
  • fever
  • headache
  • myalgia

Diagnosis tends to be by serology, which becomes positive 7 to 10 days after the onset of disease.

Treatment is with doxycycline.

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Rocky Mountain Spotted Fever

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Rocky Mountain Spotted Fever is a tick-borne disease caused rickettsia rickettsii, which is a gram negative obligate intracellular bacteria.

It is endemic in both North and South America.

Symptoms begin 2 to 14 days after the tick bite:
  • fever
  • headache
  • abdominal pain
  • myalgia
  • rash - appears an average of 3 days after onset of illness - classically petechial

Diagnosis: ELISA. Note blood cultures are of little use as rickettsia rickettsii is poorly cultured, and that PCR of its DNA isn't that useful either as it lacks sensitivity.

Treatment is doxycycline 

Prognosis: mortality rate untreated is up to 80%; treated is 3%.

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Secret collector of interesting anonymised ECGs. Fan of the Bath Photomarathon. Lover of cream teas. [Sarah Hudson] (Your Picture)