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Showing posts with label MRCP. Show all posts

Motor neurone disease

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Motor neurone disease (MND) is a progressive neurodegenerative disease. It tends to affect those in their 60s/70s. 

There are 3 subtypes of MND: 

1) Amyotrophic lateral sclerosis = Classic motor neurone disease 
  • upper and lower motor neurons affected 
  • commonest form patterns of onset are 
    • limb onset 
      • commonest
      • asymmetrical distal weakness – patients often have difficulty opening bottles/writing if hand is affected, or difficulty going upstairs if a foot is affected 
      • brisk reflexes 
      • muscle wasting 
    • bulbar onset 
      • around 20% of cases start like this 
      • slurring of speech 
      • wasting and fasciculation of tongue 
      • dysphagia 
      • often associated with emotional lability 
    • respiratory onset 
      • rarest form of onset 
      • dyspnoea 
      • orthopnoea 
2) Primary lateral sclerosis 
  • pure upper motor neurone disease 
  • 2% of cases of MND
  • look for upper motor neurone features such as 
    • spasticity 
    • hyperreflexia 
    • extensor plantar response 
3) Progressive muscular atrophy 
  • pure lower motor neurone disease 
  • 4% of cases of MND 
  • look for lower motor neurone features such as 
    • muscle wasting 
    • muscle weakness 
    • fasciculation 
    • absent reflexes 
  • slight male preponderance
  • earlier age of onset 
  • better prognosis than ALS 

Most cases are sporadic although around 5-10% of cases are familial; these tend to have a younger onset 

Diagnosis of MND is usually clinical with supporting electrophysiological evidence and tests to eliminate other possible diagnoses. Investigations may include:
  • Nerve conduction tests 
  • Electromyography 
  • Tests to eliminate other conditions which can present similarly, such as: 
    • Thyroid tests - ? hyperthyroidism 
    • Calcium - ? hyperparathyroidism 
    • B12 
    • Copper 
    • Lyme serology 
    • MRI - ? MS 

Management can include 
  • Riluzole (an inhibitor of glutamate release) - recommended by NICE - prolongs life by around 2 months 
  • NIV if required 
  • NG feeding if required 
  • Symptomatic management 
    • Drooling: Transdermal or sublingual hyoscine, oral atropine, TCA, beta blockers, injection of botulinum toxin to salivary glands, irradiation of parotid gland 
    • Muscle cramps: quinine, diazepam, phenytoin 
    • Spasticity: baclofen, dantrolene, tizanidine 
    • Pain: medications as per pain ladder 
    • Multidisciplinary team approach 

Prognosis: 
  • most patients die 2 to 3 years after diagnosis 
  • poorer prognosis if 
    • onset with bulbar form of MND 
    • older age at onset 
    • lower than predicted FVC 
    • low BMI <18.5 


Possible differentials include:


References

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Extrinsic allergic alveolitis

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Extrinsic allergic alveolitis, AKA hypersensitivity pneumonitis, is a group of immune-mediated lung diseases in which repeated inhalation of allergens results in type III and type IV hypersensitivity reactions with granulomatous inflammation. 

Most cases take years of repeated exposure to the allergen before EAA develops; once it does, symptoms tend to occur 4 to 8 hours after inhalation of an allergen: 
  • Dyspnoea 
  • Unproductive cough 
  • Fever 
  • Myalgia

Chronically patients have permanent dyspnoea, emphysema, pulmonary fibrosis and weight loss, with the potential to progress to respiratory failure and cor pulmonale. 

Forms of extrinsic allergic alveolitis include: 
  • Farmer’s lung – thermophilic actinomycetes, Saccharopolyspora rectivirgula (Micropolyspora faeni), and Aspergillus umbrosi 
  • Bird fancier lung 
  • Malt worker’s lung – aspergillus species
  • Hot tub lung - mycobacterium avium complex
  • Japanese summer disease – various fungi from moldy houses – t. cutaneum

Investigations 
  • CXR – pulmonary infiltrates; fibrosis upper lobes > lower lobes
  • HRCT – ground glass shadowing, gas trapping
  • Lung function tests: 
    • Spirometry – restrictive pattern
    • Diffusing capacity for carbon monoxide – decreased 
  • Bronchial lavage – initially neutrophils then lymphocytes

Management 
  • Avoidance of allergen
  • ?steroids

References

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Chlamydia

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Chlamydia, caused by c. trachomatis, is the most common curable sexually transmitted infection in the UK. 

5-10% of sexually active individuals aged 20-24 are estimated to be infected 

Symptoms: 
  • Females: 
    • Asymptomatic in 70% 
    • Purulent vaginal discharge 
    • Mucopurulent cervicitis 
    • Dysuria
    • Lower abdominal pain 
    • Post coital or intermenstrual bleeding 
  • Males:
    • Asymptomatic in 50% 
    • Urethral discharge
    • Dysuria 

Diagnosis 
  • Swab of cervix or vulvo-vagina (female) or first voided urine (male) 
  • Nucleic Acid Amplification Test

Management
  • First line: Doxycycline 100mg bd for 7 days OR azithromycin 1g once only 
  • Second line: erythromycin 500mg bd for 10-14 days OR ofloxacin 200mg bd 
  • Contact tracing – last 4 weeks if index patient is symptomatic, 6 months if asymptomatic 
  • uncomplicated genital tract infection with Chlamydia is not an indication for removal of IUD 

Complications
  • Pelvic inflammatory disease in women 
    • risk of infertility – 20%
    • Ectopic pregnancy
    • Chronic pelvic pain – 18% 
    • Fitz-Hugh-Curtis syndrome
      • Inflammation of the liver capsule associated with genital tract infection 
      • Classically presents with sharp RUQ pain
  • Reiter’s syndrome 

References

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Epicondylitis

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Tennis elbow
  • Lateral epicondylitis 
  • Commoner than medial epicondylitis 
  • Characterised by 
    • Pain and tenderness over lateral epicondyle 
    • Pain on dorsiflexion of wrist 

Golfer’s elbow 
  • Medial epicondylitis 
  • Characterised by 
    • Pain and tenderness over medial epicondyle 
    • Pain on wrist flexion and elbow pronation 

Treatment 
  • NSAIDs – topical or oral 
  • Physiotherapry
  • Corticosteroid injections – conflicting evidence as to efficacy 


References:

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Normal pressure hydrocephalus

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The classical triad of normal pressure hydrocephalus is 
  • Gait abnormality 
  • Urinary incontinence 
  • Dementia 

However, only a minority of patients present with this triad, and gait abnormality is the commonest finding.  The gait associated with normal pressure hydrocephalus is described as shuffling or broad-based.

It is one of the few reversible causes of dementia.

Investigations: 
  • CT/MRI head – looking for ventricular enlargement
  • Large volume lumbar puncture - ? temporary improvement of symptoms 
  • CSF infusion test 

Treatment is by shunting - ventriculoperitoneal, ventriculopleural or ventriculoatrial. 
Around 60% of patients show improvement after shunting. 


References:

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P450 inducers and inhibitors

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P450 inducers = increase metabolism of drugs metabolised by cytochrome P450 and thus decrease drug effect
  • Carbamazepine 
  • Phenytoin 
  • Rifampicin 
  • Phenobarbital 
  • Tobacco 
  • Chronic alcohol 
  • St Johns Wort 

P450 inhibitors = decrease metabolism of drugs metabolised by cytochrome P450 and thus increase drug effect
  • Cardiac
    • Amiodarone 
    • Verapamil
    • Quinidine
  • Antibiotics
    • Ciprofloxacin
    • Erythromycin
    • Metronidazole
    • Trimethoprim
    • Isoniazid
  • Antifungals
    • Fluconazole
    • Terbafine
  • HIV antivirals
  • Antacids
    • Cimetidine
    • Omeprazole
  • Psychiatric drugs
    • TCA
    • SSRIs especially fluoxetine
    • Haloperidol
  • Others
    • Methadone
    • Grapefruit juice

Drugs metabolised by cytochrome P450 include:
  • Cardiac
    • Beta blockers
    • Angiotensin II blockers
    • Statins
  • Psychiatric drugs
    • TCA
    • SSRI
    • antipsychotics
  • Analgesics
    • Tramadol
    • Codeine
    • Ibuprofen
  • Antiepileptics
  • Other
    • Sildenafil
    • Warfarin
    • Donepezil
    • PPIs
    • Glipizide
    • Theophylline


Small print gem: the name cytochrome P450 comes from the fact the enzymes are inside the cell (cyto) and contain a haem pigment (chrome P) that absorbs light at a wavelength of 450nm when exposed to carbon monoxide



References:

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Goodpasture’s syndrome

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Goodpasture’s syndrome is a rare autoimmune disease characterised by: 
  • Pulmonary haemorrhage 
  • Rapidly progressive glomerulonephritis and renal failure 

The cause is anti-GBM antibodies acting against type IV collagen 

Pulmonary haemorrhage occurs most commonly in patients who are smokers, or are exposed to paint of gasoline fumes 

Treatment:
  • Prednisolone 
  • Cyclophosphamide 
  • Plasma exchange 


References:

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Age-related macular degeneration

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Age-related macular degeneration is defined as changes which occur in the central area of the retina (=macula) in individuals aged over 50 without any obvious cause.

It is the leading cause of blindness in the UK.

Risk factors
  • Smoking 
  • Increasing age 
  • Family history 
  • Caucasian 
  • Previous cataract surgery

2 types:
  • Dry 
    • Characterised by drusen = lipid material in Bruch’s membrane 
    • Often asymptomatic 
  • Wet 
    • Characterised by choroidal neovascularisation – new vessels are fenestrated so allow blood to leak, leading to macular haemorrhage 
    • worse prognosis

Presentation:
  • Dry 
    • Often detected on routine fundoscopy 
    • If fovea involved – deterioration of central vision 
  • Wet 
    • Central visual blurring, straight lines appear wavy 
    • Decreased vision


Management:
  • Dry and wet:
    • Smoking cessation
    • Diet 
      • Diet rich in fruit and vegetables (antioxidant vitamins) and oily fish (omega 3 fatty acids) – not conclusively proven to help but thought to be beneficial
      • AREDS formula – very high dose antioxidants (vitamin C, vitamin E, beta-carotene) and zinc
        • Beta-carotene is contra-indicated in smokers as increases the risk of lung cancer
        • Vitamin E associated with increased risk of heart failure in individuals with diabetes or vascular disease (HOPE study)
  • Wet only:
    • Intravitreal injection of anti-vascular endothelial growth factor (anti-VEGF) – such as ranibizumab 
    • Argon laser
    • Photosensitising dye (verteporfin) then laser

Small print gem: Patients with visual loss such as macular degeneration may suffer from visual hallucinations. This is known as Charles Bonnet Syndrome.


References:

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Phaeochromocytoma

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Phaeochromocytomas are rare tumours of chromaffin cells which produce catecholamines. 

Presenting features may include:
  • hypertension 
  • headache 
  • palpitations 
  • diaphoresis (=excessive sweating) 
  • nausea and vomiting 

10% are familial, as part of MEN II, neurofibrosis or Von Hippel Lindau syndrome 
10% are bilateral, 10% are malignant and 10% are extraadrenal 

Extraadrenal sites include the organ of Zuckerkandl and bladder. 

Diagnosis is by 24 hour urinary VMA. Localisation is then by CT/MRI. 

Management is surgical with pre operative alpha blockade (prazosin or phenoxybenzamine)


Small print gem: Metoclopramide must be avoided in patients with phaechromocytoma as it increases noradrenaline release via presynaptic dopamine receptor blockade, which in the presence of a phaechromocytoma can cause severe hypercatecholaminaemia. 


References:

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Zollinger-Ellison syndrome

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Zollinger-Ellison syndrome is a condition characterised by multiple ulcers in the GI tract secondary to a gastrinoma(s). 

The commonest location of the gastrinoma is the duodenum (75%) followed by the pancreas (25%).

Studies suggest between 20 and 65% of gastrinomas are malignant. 

25% of cases of Zollinger-Ellison syndrome are associated with MEN-1 

Presentation: 
  • Abdominal pain from ulcers 
  • Gastric reflux
  • Diarrhoea 
  • Steatorrhoea and malabsorption – due to inactivation of pancreatic enzymes and damage to enterocytes by acid

Diagnosis:
  • Raised fasting gastrin level 
  • However, hypochlorhydria (due to chronic atrophic gastritis or prolonged PPI use) will also cause a raised fasting gastrin level. To differentiate IV secretin can be administered – this will result in a raised gastrin level in Zollinger-Ellison syndrome but no rise in achlorhydria. 

Treatment: 
  • High dose PPI 
  • Ocreotide (somatostatin analague) – reduces gastrin secretion 
  • Possibly surgery

References:

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Trigeminal neuralgia

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Trigeminal neuralgia is characterized by brief episodes of stabbing pain in the distribution of the trigeminal nerve.

The pain may be triggered by light touch, talking or even a breeze.

It is usually unilateral, with the right side of the face more commonly affected. One or more branches may be implemented in the pain; the most common branch involved is the maxillary and the least common the ophthalmic. Particular ‘trigger points’ can often be identified.

Incidence is 4 per 100000.
Females are slightly more affected than males.
It is rare under the age of 40 – a patient under 40 should prompt investigation for other causes.

The underlying pathophysiology is now believed to be demyelination of the nerve root, classically due to pressure.

First line treatment is carbamezepine. Other options include gabapentin, phenytoin, clonazepam and baclofen. Surgical options include microvascular decompression.


References:

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Disseminated intravascular coagulation

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Disseminated intravascular coagulation (DIC) is the pathological widespread activation of coagulation, resulting in thrombosis, haemorrhage or both.

Blood tests will show:
  • prolonged PT
  • prolonged aPTT
  • massively raised d-dimer levels
  • low platelets
  • low fibrinogen
  • schistocytes – around 50% of cases

Of these, it is the level of fibrinogen which best correlates to the severity – but note that as it is an acute phase protein it may initially be high so take time to become low.

Causes of DIC include:
  • obstetric – multiple, including placental abruption, HELLP
  • trauma – crush injury, burns, frostbite
  • septicaemia
  • malignancy
  • immune-mediated: transfusion reaction, severe allergic reaction, acute transplant rejection
  • toxins – bites, amphetamine overdose

The treatment is:
  • treat the cause
  • give platelets if platelets <50
  • cryoprecipitate – this replaces fibrinogen
  • FFP
  • activated protein C if septic.

References:

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Pneumothorax

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A pneunothorax is a collection of air in the pleural cavity.  The main subdivisions are:
  • primary spontaneous pneumothorax = occurring in a healthy individual
  • secondary spontaneous pneumothorax = occurring in an individual with underlying lung disease
  • traumatic pneumothorax = shouldn't be managed by medics!
Classical symptoms: dyspnoea and chest pain.
Classical signs: reduced breath sounds, reduced chest expansion and hyperresonance on the side of the pneumothorax.  Rarely a 'clicking' sound at the cardiac apex.

Risk of pneumothorax is increased in:
  • smokers
  • tall people
  • HIV infection (believed to be due to pneumocystis jiroveci) 


Pneumothorax is not usually associated with exercise


Conditions predisposing to development of a secondary pneumothorax include:
  • COPD
  • asthma
  • interstitial lung diseases
  • lung infection
  • connective tissue diseases such as


The BTS guidelines on the management of spontaneous pneumothorax are summarised in the diagrams below:



An unusual form of pneumothorax is a catamenial pneumothorax.  This is pneumothorax in women occurring usually within 72 hours before or after menstruation, associated with chest pain, dyspnoea and haemoptysis.  It is believed to be due to ectopic endometriosis.


Small print gem: although a tension pneumothorax is classically decompressed in the 2nd intercostal space, a 14G venflon will not be long enough to reach the parietal pleural in a third of patients, in which case the 4th or 5th intercostal space should be used.


References


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Idiopathic thrombocytopenic purpura

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Idiopathic thrombocytopenic purpura, also known as autoimmune thrombocytopenic purpura, is a disease characterised by IgG autoantibody-mediated platelet destruction resulting in a low platelet count of 150 x10 9 or less. It is a diagnosis made by excluding other causes of thrombocytopenia.

In children ITP tends to occur after viral infections and be self-limiting. In adults it tends to last longer and often follows a chronic course.

Treatment is only needed if the patient is symptomatic or the platelets are <20.
  • First line = oral prednisolone - 80% respond
  • If no response in 3 months --> splenectomy – curative for 2/3s of patients 
  • Other options include IV IG or immunosupressive drugs. 

Small print gem: Evan's syndrome = ITP +AIHA.


References:

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Brugada Syndrome

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Brugada Syndrome is a condition in which abnormal sodium channel proteins can result in ventricular arrhythmias and sudden cardiac death in a patient with a structurally normal heart.

It is associated with 3 ECG patterns, the classic being partial/RBBB and ST elevation in the right precordial leads.

Prevalance is estimated at 5 per 10000.
It is commonest in Asians.
Men are 8 to 10 times more affected than women phenotypically, although the genotype prevalence is the same for both genders.
Around 30% of cases are associated with a SCN5A mutation.  This is autosomal dominant.


Sudden cardiac death from Brugada is commonest in the 4th decade of life. Around 1 in 5 patients with sudden cardiac death from Brugada would have previously had a syncopal episode. Interestingly arrhythmias associated with Brugada tend to occur during periods of vagal dominance, ie at rest or asleep.


Ajmaline is the ‘best’ drug to unmask Brugada syndrome. Other drugs in use include flecainide and procainamide.

Treatment is:
a)    to avoid precipitants of arrhythmias
  • fever
  • drugs such as flecainide, ajmaline, procainamide, propafenone, lithium, amitriptyline
b)    ICD


Small print gem:  It is a relatively new condition, first described in 1992, and has other names including lai tai in Thailand and pokkuri in Japan                                                                                                      
                                                                                                                                                                          
                                                                                                                                                                        
References
Benito, B., Brugada, J., Brugada, R and Brugada, P. Brugada Syndrome. Rev Esp Cardiol. 2009; 62(11): 1297-315.                                                                                                               
Postema, P. et al. Drugs and Brugada syndrome patients: review of the literature, recommendations, and an          up-to-date website. Heart Rhythm. 2009; 6(9): 1335-41                                                                                                          

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Milk-alkali syndrome

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Milk-alkali syndrome is the triad of hypercalcaemia, renal failure and metabolic alkalosis secondary to ingestion of large amounts of calcium and absorbable alkali.

Historically it was due to milk and alkali being given for peptic ulcer disease.  It is now becoming more prevalent again due to widespread use of calcium carbonate in the prevention of osteoporosis.  Some estimate it to now be the third most common cause of in-hospital hypercalcaemia.

Treatment is to stop the causative agent and hydrate the patient.
    
                                                                                                                                                                         

Reference:

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Dermatomyositis and polymyositis

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Polymyositis is an idiopathic inflammatory disorder of skeletal muscle. When it is associated with cutaneous lesions it is dermatomyositis.

Features:
  • Progressive proximal muscle weakness
  • Dysphonia
  • Dysphagia
  • Fever
  • Arthralgia/arthritis
  • Muscle pain
  • More rarely respiratory muscle weakness

Possible complications:
  • Cardiomyopathy
  • Intersitial lung disease
  • Malignancy – commonest in dermatomyositis; most frequently lymphoma or ovarian or gastric cancer

Skin signs:
  • Pathognomonic
    • Gottron’s papules = erthematous papules over IP/MCP/elbow/knee joints
    • Gottron’s sign = macules/plaques in same distribution as Gottron’s papules
  • Non-pathognomic signs
    • Heliotrope (liliac-purple) rash around eyelids/cheeks
    • Shawl sign = macular rash over back and shoulders
    • Periungal telangectasia

Investigations
  • Raised CK/AST/ALT/LDH
  • Raised ANA in 60-80%
  • Anti-Jo antibodies in 20% of dermatomyositis
  • Abnormal EMG

Treatment is:
  • Prednisolone
  • Methotrexate/cyclosporin
  • Screen for malignancy

Reference:

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Familial hypocalciuric hypercalcaemia

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Familial hypocalciuric hypercalcaemia is an autosomal dominant condition which results in asymptomatic mild hypercalcaemia.

Bloods show mildly raised calcium and a normal or mildly raised PTH.

Familial hypocalciuric hypercalcaemia can be distinguished from primary hyperparathyroidism by fractional urinary calcium excreation:
  • Patients with familial hypocalciuric hypercalcaemia: fractional urinary calcium excreation <0.01
  • Patients with primary hyperparathyroidism: fractional urinary calcium excreation >0.02

It is important to distinguish the two as primary hyperparathyroidism requires treatment whilst familial hypocalciuric hypercalcaemia does not.

References:

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Acromegaly

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Acromegaly is a condition caused by excess growth hormone. Almost all cases are due to a pituitary tumour.


Classical features include:
  • Soft tissue growth (large hands, coarsening of features etc)
  • Hyperhydrosis
  • Headaches
  • Parasthesia
  • Hypertension
  • Impaired glucose tolerance/diabetes
  • Hoarse voice

MRCP smaller-print features include:
  • Colonic polyps
  • Proximal myopathy
  • Arthralgia
  • Raised triglycerides
  • Osteopenia
  • Cardiomegaly – up to 90% in long-term patients
  • OSA


Diagnosis is by the failure of GH to decrease to less than 1 microgram/l 2 hrs after an oral glucose challenge of 75g. False positives may occur in pregnancy, diabetics, renal/hepatic impairment, obesity or those on oestrogen therapy.

Serum IGF-1 is raised but this is only useful for screening.


Treatment:
  • Transphenoidal surgery – 50-70% cure
  • Octreotide = somatostatin analogue – 70% efficacy – causes gallstones in 30%...
  • Pegvisomant = competitive GH receptor antagonist – 80% effective
  • Radiotherapy – but takes up to 20 yrs(!) to work
  • Dopamine agonists – bromocriptine not believed to be effective; cabergoline works in less than 10%


Small print gem: IGF1 is the target hormone for GH and mediates most of GH’s growth-promoting actions. 80% of IGF1 is made in the liver.


References:

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Hypercalcaemia

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Calcium homeostasis is primarily controlled by parathyroid hormone and hydroxylated vitamin D. Parathyroid hormone is produced by the parathyroid gland and vitamin D is either indigested in the diet or synthesized in the skin via exposure to sunlight. The mechanisms of action are outlined in the diagram below:



Hypercalcaemia can result in the following signs and symptoms (beyond the classical ‘stones, bones, abdominal groans and psychic moans…’)
  • Polyuria
  • Polydipsia
  • Renal stones
  • Nausea and vomiting
  • Anorexia
  • Constipation
  • Confusion
  • Psychotic behaviour
  • Headache
  • Bone pain
  • Hypertension (rare)

Causes of hypercalaemia:

Malignant disease can cause hypercalcaemia due to:
  • Bone involvement – boney mets - ‘bronchus, breast, byroid, brostate and bidney’ (AKA bronchus, breast, thyroid, prostate and kidney) and myeloma
  • Parathyroid Hormone related Peptide (PTHrP) produced by tumour, especially squamous cell tumours such as lung, oesophagus and breast, renal and bladder tumours.

ECG changes seen in hypercalcaemia can include: short QT, bradycardia, bundle branch block or AV block

Treatment is:
  • Treat cause
  • Normal saline
  • Pamidronate
Small print gem: Hypercalcaemia increases sensitivity to digoxin

References:

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