Differentials
Peripheral neuropathy
SIGNS / SYMPTOMS
It is not possible to differentiate vitamin B1 deficiency-related neuropathy from other causes of distal peripheral neuropathy such as diabetes, alcoholism (direct toxic effect), vitamin B12 deficiency, malignant disease, and chronic renal failure on clinical grounds.
The presence of risk factors may lead to a clinical suspicion of vitamin B1 deficiency.
INVESTIGATIONS
Electromyography and nerve conduction studies: reveal specific type of peripheral neuropathy.
Acute encephalitis
SIGNS / SYMPTOMS
It is not possible to differentiate Wernicke's encephalopathy from other causes of acute encephalitis such as Miller-Fisher syndrome, multiple sclerosis, variant Creutzfeldt-Jakob disease, paraneoplastic encephalitis, and ventriculo-encephalitis on clinical grounds.
The presence of risk factors may lead to a clinical suspicion of vitamin B1 deficiency.
INVESTIGATIONS
MRI: may show nerve root enhancement in Miller-Fisher syndrome, and active lesions reflecting perivascular inflammation and breakdown of the blood-brain barrier in multiple sclerosis. In paraneoplastic encephalitis, MRI may be unremarkable although T2-weighted hyperintensity may be noted in the mesial temporal lobes and associated limbic structures. Viral encephalitis may show increased T2 signal intensity in the mesial temporal lobes and inferior frontal grey matter.
CSF examination for bacterial culture and viral PCR: reveals specific pathogen in infectious encephalitis. CSF protein: raised in most forms of encephalitis. Its presence or absence does not help to differentiate Wernicke's encephalopathy.
Anti-GQ1b antibodies: may be positive in Miller-Fisher syndrome.
Autoantibodies to glutamic acid decarboxylase: may be present in paraneoplastic encephalitis.
Graves' disease
SIGNS / SYMPTOMS
Graves' disease can cause high-output cardiac failure. Symptoms include weight loss, heat intolerance, and palpitations. Signs include a neck goitre, exophthalmos, lid retraction, and tremor.
INVESTIGATIONS
Thyroid function tests: high free T4/T3 and suppressed TSH.
Anaemia
SIGNS / SYMPTOMS
Severe anaemia can cause high-output cardiac failure. History of blood loss (e.g., GI, menorrhagia). Examination reveals pallor.
INVESTIGATIONS
FBC: low Hb and reduced mean cell volume in microcytic anaemia.
Paget's disease
SIGNS / SYMPTOMS
Paget's disease can cause high-output cardiac failure. Symptoms include bone pain, headaches, and hearing loss.
INVESTIGATIONS
Alkaline phosphatase (bone isoform): elevated isotope bone scan: shows preferential uptake of the isotope technetium in the Pagetic foci.
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