Neuroradiology differential diagnosis
These alternatives come from the neuro cases, covering congenital, infective, vascular and neoplastic disease. Each row states the feature that argues against the alternative in the case it came from; follow the case link for the images and the full discussion.
| Alternative diagnosis | Feature that argues against it | Case |
|---|---|---|
| Acute Wernicke encephalopathy | Wernicke encephalopathy involves the medial thalami, periaqueductal grey matter and mammillary bodies and is associated with alcohol misuse or malnutrition, whereas metronidazole toxicity favours the dentate nuclei and splenium. | Metronidazole-induced encephalopathy |
| Alobar holoprosencephaly | Holoprosencephaly shows a single monoventricle with fused thalami and absent midline structures, whereas this case has two separate lateral ventricles with a preserved midline. | Hydrocephalus |
| Aqueductal stenosis | Aqueductal stenosis dilates the lateral and third ventricles with a normal fourth ventricle, and it produces a prominent upstream dilation rather than diffuse, symmetric ventriculomegaly. | Hydrocephalus |
| Arteriovenous malformation | An arteriovenous malformation contains flow voids and enlarged feeding arteries or draining veins, and haemorrhage is usually associated with these vascular structures. | Giant pontine cavernoma |
| Autoimmune paraneoplastic encephalitis | Autoimmune encephalitis tends to involve the limbic system with bilateral medial temporal hyperintensity and is associated with positive neuronal antibodies and a subacute neuropsychiatric course. | Acute disseminated encephalomyelitis (ADEM) |
| Bihemispheric diffuse glioma | A diffuse glioma produces progressive, expansile T2 hyperintensity with mass effect, altered perfusion and no spontaneous regression on follow-up, unlike the resolving lesions of ADEM. | Acute disseminated encephalomyelitis (ADEM) |
| Central nervous system lymphoma | Lymphoma is usually periventricular, homogeneous, markedly diffusion-restricted and shows intense uniform enhancement without central necrosis in immunocompetent patients. | Intracranial tuberculous granuloma (tuberculoma) |
| Cerebral toxoplasmosis | Toxoplasmosis occurs in immunocompromised patients and typically produces multiple basal ganglia lesions with homogeneous or ring enhancement and the asymmetrical target sign. | Intracranial tuberculous granuloma (tuberculoma) |
| Choroid plexus cyst | A choroid plexus cyst follows cerebrospinal fluid signal on all sequences, is not hyperdense on unenhanced CT and does not contain the proteinaceous content responsible for T1 hyperintensity. | Colloid cyst of the third ventricle |
| Chronic subdural haematoma | A chronic subdural haematoma is a crescentic collection with blood signal and a membrane, often unilateral, without diffuse pachymeningeal enhancement or brainstem sagging. | Spontaneous intracranial hypotension |
| Craniopharyngioma | A craniopharyngioma arises in the suprasellar cistern, commonly contains calcification and cystic components and enhances, whereas a colloid cyst sits at the foramen of Monro without enhancement. | Colloid cyst of the third ventricle |
| Diffuse pontine glioma | A diffuse pontine glioma expands the pons with T2 hyperintensity, lacks the popcorn appearance and haemosiderin rim, and does not show blooming on T2* imaging. | Giant pontine cavernoma |
| Disc herniation | A disc herniation is centred on an intervertebral disc level and is continuous with the disc, while a spontaneous epidural haematoma extends across several segments dorsal to the thecal sac. | Spontaneous spinal epidural haematoma |
| Dural metastasis or granuloma | Dural deposits are often multifocal and nodular with a known systemic disease, and lack the uniform enhancement and hyperostosis of a meningioma. | Olfactory groove meningioma |
| Enterovirus encephalomyelitis | Enterovirus infection produces a febrile illness with rhombencephalitis and often anterior horn cell involvement, and the lesions do not resolve simply on withdrawal of a drug. | Metronidazole-induced encephalopathy |
| Epidural lipomatosis | Epidural lipomatosis follows the signal of fat on all sequences and suppresses on fat-saturated images, whereas a haematoma shows blood signal and STIR hyperintensity. | Spontaneous spinal epidural haematoma |
| Epidural metastasis | Metastatic epidural disease is accompanied by bone destruction, abnormal marrow signal and enhancement of the deposit, and often involves the vertebral body rather than forming a purely dorsal biconvex collection. | Spontaneous spinal epidural haematoma |
| Epstein-Barr virus encephalitis | EBV encephalitis usually follows a febrile illness with lymphadenopathy and shows more symmetric involvement of the basal ganglia and thalami, often with meningeal enhancement. | Acute disseminated encephalomyelitis (ADEM) |
| Fetal hydrocephalus | Fetal hydrocephalus is diagnosed in utero and may resolve or progress after birth, whereas this infant has a term delivery with established postnatal ventriculomegaly and systemic anomalies. | Hydrocephalus |
| Forniceal or third ventricular glioma | A glioma is usually T2 hyperintense and enhances to a variable degree, and it tends to infiltrate rather than form a sharply marginated hyperdense cyst. | Colloid cyst of the third ventricle |
| Fungal, parasitic or mycobacterial abscess | These infections often show multiple lesions, a thicker or irregular capsule and specific features such as a scolex or tuberculoma-like nodule, and require microbiological correlation. | Pyogenic brain abscess with intraventricular rupture |
| Glioblastoma | Glioblastoma shows an irregular, thick and nodular enhancing rim with central necrosis and increased perfusion, whereas a pyogenic abscess has a smooth thin capsule, restricted diffusion of the core and a dual-rim sign. | Pyogenic brain abscess with intraventricular rupture |
| Hypertensive haemorrhage | Hypertensive haemorrhage occurs typically in the basal ganglia, thalamus or pons in older patients with longstanding hypertension and shows a single acute haematoma rather than a multilobulated lesion with a haemosiderin rim. | Giant pontine cavernoma |
| Idiopathic hypertrophic pachymeningitis | Hypertrophic pachymeningitis produces nodular or mass-like dural thickening that may enhance intensely and does not cause brain sagging, venous engorgement or a spinal fluid collection. | Spontaneous intracranial hypotension |
| Infective meningitis | Infective meningitis enhances the leptomeninges rather than the dura and is accompanied by fever, neck stiffness and cerebrospinal fluid pleocytosis. | Spontaneous intracranial hypotension |
| Marchiafava-Bignami disease | Marchiafava-Bignami disease affects the corpus callosum in patients with chronic alcohol misuse and does not typically involve the dentate nuclei symmetrically. | Metronidazole-induced encephalopathy |
| Metastasis | A metastasis shows surrounding vasogenic oedema, usually enhances and is often multiple, without the complete haemosiderin rim of a cavernoma. | Giant pontine cavernoma |
| Metastasis | A metastasis usually arises at the grey-white matter junction with marked oedema, but its rim is thicker and more irregular and the central necrosis does not show the low ADC value of pus. | Pyogenic brain abscess with intraventricular rupture |
| Methyl bromide poisoning | Methyl bromide poisoning causes cerebellar and brainstem lesions after occupational exposure, and the history of exposure rather than drug intake is the discriminating factor. | Metronidazole-induced encephalopathy |
| Multiple sclerosis | Multiple sclerosis produces smaller periventricular ovoid lesions perpendicular to the ventricles, often with chronic black holes, and new lesions appear over time, whereas ADEM is monophasic with large, poorly marginated lesions that resolve. | Acute disseminated encephalomyelitis (ADEM) |
| Neurocysticercosis | A cysticercal cyst shows a mural scolex, may have surrounding oedema in the vesicular stage and does not present as a hyperdense T1-hyperintense lesion at the foramen of Monro. | Colloid cyst of the third ventricle |
| Neurocysticercosis | A cysticercal cyst is usually smaller, contains a mural scolex, shows no oedema when calcified and does not have the caseous, non-restricted core of a tuberculoma. | Intracranial tuberculous granuloma (tuberculoma) |
| Olfactory neuroblastoma | An olfactory neuroblastoma arises in the nasal cavity, destroys the cribriform plate and contains calcification, whereas an olfactory groove meningioma is centred intracranially with hyperostosis and homogeneous enhancement. | Olfactory groove meningioma |
| Porencephalic cyst | A porencephalic cyst is a focal parenchymal cavity communicating with the ventricle and surrounded by gliosis, not a uniform dilatation of the entire ventricular system. | Hydrocephalus |
| Post-lumbar puncture headache | A post-lumbar puncture leak produces identical imaging findings but is distinguished by the procedure history, whereas spontaneous intracranial hypotension occurs without an obvious cause. | Spontaneous intracranial hypotension |
| Pyogenic brain abscess | A pyogenic abscess shows marked restricted diffusion of its central pus with a thin, smooth enhancing capsule, whereas a tuberculoma has no central diffusion restriction and a thicker irregular rim. | Intracranial tuberculous granuloma (tuberculoma) |
| Sinonasal carcinoma | Sinonasal carcinoma presents with nasal obstruction, bone erosion and mucosal disease, and does not show the broad dural base and dural tail of a meningioma. | Olfactory groove meningioma |
| Skull base metastasis | A metastasis usually causes bone destruction, heterogeneous enhancement and marked oedema, and is often multiple or associated with a known primary tumour. | Olfactory groove meningioma |
| Spinal epidural abscess | An epidural abscess usually presents with fever, raised inflammatory markers and vertebral discitis or osteomyelitis, and shows peripheral enhancement with restricted diffusion of pus. | Spontaneous spinal epidural haematoma |
| Tumour radionecrosis | Radionecrosis follows radiotherapy, shows a soap-bubble or Swiss-cheese enhancement pattern and has no restricted diffusion of the central contents. | Pyogenic brain abscess with intraventricular rupture |
The confirmed diagnosis of each case is stated on the case page and is not repeated here. Sorted alphabetically; the order says nothing about probability.