Differential Lists Flashcards
Eye movements & palsies
Describe normal nerve and muscle control of eye movements
o SO4 (superior oblique trochlear nerve), LR6 (abducens nerve), all the rest are controlled by 3 o Superior oblique intorts the eye o Lateral rectus abducts the eye
Right eye Left eye SR (III) IO (III) IO (III) SR (III)
LR (VI) MR (III) MR (III) LR (VI)
IR (III) SO (IV) SO (IV) IR (III)
3rd nerve palsies
- Aetiology
- Clinical features (3)
6th Nerve palsy
- Aetiology
- Clinical features (3)
Third (oculomotor) nerve palsy
- Aetiology:
Central: vascular (e.g. brain stem infarct), tumour, demyelination (rare), trauma
Peripheral:
• Compressive lesions (aneurysm on the PCA), tumour, nasopharyngeal carcinoma, meningitis
o Orbital lesions – Tolosa-Hunt syndrome (superior orbital fissure syndrome – painful lesion of 3, 4, 6 and V1)
• Infarction: diabetes mellitus, arteritis
• Trauma
• Cavernous sinus lesions
o Features:
1. Complete ptosis (partial may occur with incomplete lesion)
2. Divergent strabismus (eye ‘down and out’)
3. Dilated pupil unreactive to direct or consensual light and accommodation
Exclude a 4th nerve lesion by asking the patient to tilt their head to the side of the lesion and the affected eye will intort if CN4 is intact
Sixth (abducens) nerve palsy
- Features:
1. Failure of lateral eye movement
2. Affected eye is deviated inwards in severe lesions
3. Diplopia – maximal on looking to affected side; images horizontal
o Aetiology:
Bilateral: Trauma, Wernicke’s, Raised ICP, Mononeuritis multiplex
Unilateral:
• Central: stroke, tumour, Wernicke’s, MS (rare)
• Peripheral: diabetes and other vascular lesions, trauma, idiopathic, raised ICP
Describe one-and-a-half syndrome
Localise the lesion
• One and a half syndrome = defect in conjugate gaze (i.e. connections between bilateral CN3 & 6 which coordinate eyes in unison)
o Failure of adduction of ipsilateral eye
o Associated horizontal nystagmus in contralateral eye
o Lesion in the medial longitudinal fasciculus (ipsilateral to eye which fails to adduct)
Motor predominant neuropathy
- CIDP
- Hereditary sensorimotor neuropathy/Charcot-Marie Tooth
- Diabetes mellitus
Other (mixed):
- Alcohol
- Paraneoplastic (lung, ovary, breast)
- Connective tissue disease, vasculitis
Sensory predominant neuropathy/sensory ataxia
- Diabetes mellitus
- Alcohol
- B12 deficiency
- Paraprotein
- Paraneoplastic
Describe neuropathy
- Small fibre
- Large fibre
Small fibre = pain & temperature
Large fibre = vibration, proprioception (myelinated)
Peripheral neuropathy workup
- Bloods:
- CBE, inflammatory markers
- Thyroid function
- B12/folate
- Serum protein electrophoresis
- HbA1c
- Autoimmune markers - BGL
- Nerve conduction studies
- Demyelinating = reduced velocity- Diabetes, CMT, paraneoplastic, CIDP
- Axonal = reduced amplitude - Diabetes, toxins, paraneoplastic
- Diabetes, CMT, paraneoplastic, CIDP
Gaits:
- High stepping
- Slapping gait
- Wide based and high stepping
- Waddling gait
- Circumduction gait
- Scissoring gait
- High stepping = neuropathic
- Unilateral = foot drop
- Ddx: common peroneal, L5 radiculopathy, ACA infarct - Bilateral “slapping” high stepping gait
- DDx: CMT, ALS, spinal lesion, distal neuropathy - Wide based and high stepping = sensory ataxia
(usually watching feet) & Romberg positive
Ddx: sensory neuropathy, spinocerebellar degeneration, MS, cord degeneration (B12) - Waddling gait = myopathic
- Shoulders and hips sway side to side
- Ddx: proximal myopathy - Circumduction gait = hemiplegic
- Reduced knee flexion
- UMNL/spasticity
- DDx: stroke - Scissoring gait = diplegic/spastic & bilateral UMNL
- foot often held in plantarflexion
- Ddx: UMNL lesion, cord/spinal lesion, MS, hereditary spastic paraparesis
Internuclear ophthalmoplegia
- Impaired ADDuction of ipsilateral eye
- Nystagmus of contralateral eye
- Adduction normal on covering the other eye
Lesion of the medial longitudinal fasciculus of pons
DDx:
- Demyelination
- Stroke
- Tumour (pontine glioma)
Parinaud’s syndrome
- Loss of vertical gaze
- Retraction-convergence nystagmus
- Loss of light reflex (accommodation intact)
Dorsal midbrain lesion
DDx:
Pinealoma, demyelination, stroke
Peripheral: diabetes
Differentials for Parkinsonism
- Idiopathic Parkinson’s disease
- Asymmetric
- No red flags
- Responds to L-dopa trial - Progressive supranuclear palsy
- Abnormal vertical gaze (downward most specific)
- Frontalis overactivity
- Axial rigidity
- Early falls
- MRI: midbrain atrophy; look at midbrain:pons ratio- Hummingbird sign
- Multiple systems atrophy
- Variable parkinsonism
- Cerebellar signs
- Autonomic dysfunction
- Pyramidal signs
- MRI: multiple areas of atrophy, Hot Cross bun sign (pons) - Corticobasal degeneration
- Alien limb phenomenon
- Apraxia
- Cortical sensory loss (2 point discrimination, agraphaesthesia, astereognosis) - Drugs:
- Anti-dopaminergics
- Valproate
- Methyldopa - Normal pressure hydrocephalus
Splenomegaly differentials
Massive:
- Myelofibrosis
- CML
- Splenic lymphoma
(4. Malaria, leishmaniasis)
Moderate:
- Portal hypertension
- Myeloproliferative disorders
- EBV
Mild:
All of above
Rheumatoid arthritis/Felty’s syndrome (neutropaenia)
Haemolytic anaemia
Cirrhosis/Liver disease differentials & investigations
DDx:
Alcohol
NAFLD
Viral hepatitis
Investigations:
- Childs-Pugh markers: bilirubin, albumin, INR
- AST: ALT ratio (>2 suggests alcoholic liver disease)
- Hepatitis serology
- Antibodies (ANA, anti-mitochondrial, anti-smooth muscle, anti-LKM)
- alpha-1-antitrypsin deficiency
- ferritin
- Caeruloplasmin
- Ascites sampling
- USS liver for hepatocellular carcinoma / thrombosis
Features suggesting specific liver disease aetiology:
- Alcohol
- Primary biliary cirrhosis
- Haemachromatosis
- Alcohol = Dupuytren’s contactures, parotid enlargement, Wernicke’s, cerebellar
- Primary biliary cirrhosis = xanthelasma, tendon xanthoma, excoriations (usually a middle aged woman)
- Haemachromatosis = bronzing of the skin with 2nd/3rd MCP arthropathy and diabetes
Lower lobe predominant ILD
RASCO Rheumatoid arthritis Asbestosis Scleroderma Idiopathic PF Other medications: amiodarone, methotrexate
