La esposa luchadora

and T1 intermediate signal, and it is avidly enhancing. A small fl uid signal cyst is seen at the anterior aspect of the mass and does not enhance. On the coronal images, there is extension into the left intra- auditory meatus, which is expanded, with an “ice-cream cone” appearance (Fig. 4.17.4, arrow). There is a mass eff ect

with distortion of the underlying middle cerebellar peduncle and partial eff acement of the fourth ven- tricle. There is also a tiny enhancing nodule seen within the intra- auditory meatus on the right, which may represent an early similar lesion (Fig. 4.17.3, arrow). The imaging fi ndings are in keeping with a vestibular schwannoma, and the presence of bilateral disease rai- ses the possibility of neurofi bromatosis type 2. I would compare with previous imaging to assess progression and recommend referral to a specialised neurosurgical unit (e.g., a neurofi bromatosis clinic).

Examination Tips

The fi nding of tumour extension into the intra- auditory meatus is highly suggestive of vestibular schwannoma as these represent over 90% of intra- canalicular tumours, and intracanalicular menin- giomas are very rare.

Calcifi cation is rare, but necrosis and cysts may be present in larger tumours.

The appearance of these larger tumours is likened to an “ice-cream cone” with the intracanalicular part representing the cone, and the cerebellopon- tine angle component the ice-cream.

Contrast enhancement is less helpful as both vestibular schwannoma and meningioma exhi- bit diff use enhancement. Therefore, thin-section T2-weighted imaging will suffi ce for the detection of vestibular schwannoma, and contrast is not usually administered.

Diff erential Diagnosis

Meningioma:

•

It has a broad dural base making an obtuse angle with the petrous bone, and is usually eccentric to the internal acoustic meatus. Metastasis or lymphoma:

•

Lesions may also be bilateral, but they are more likely to feature leptomeningeal spread as opposed to a discrete mass.

Notes

Vestibular schwannomas are also referred to as acoustic neuromas, acoustic schwannomas, or vestibular neurilemmomas.

Bilateral vestibular schwannomas are one of the characteristic clinical features of neurofi broma- tosis type 2—an autosomal dominant disorder with lesions aff ecting the central nervous system, eyes (retinal hamartomas), and skin (schwanno- mas and plaques).

The neurological manifestations can be summarised by the mnemonic MISME: multiple intracranial schwannomas, meningiomas, and ependymomas. Up to half of patients with neurofi bromatosis type 2 have meningiomas, and although the incidence increases with age, neurofi bromatosis type 2 should be considered when a meningioma is diagnosed in childhood.

Of the spinal tumours, schwannomas with their characteristic “dumbbell” shape are the most common. Meningiomas tend to involve the extra- medullary compartment while ependymomas are usually intramedullary.

Bibliography

Sriskandan N, Connor SE. The role of radiology in the diagnosis and management of vestibular schwannoma. Clin Radiol 2011;66(4):357–365

172

4 Neurological Imaging

4.18 Neurocysticercosis

Clinical History

A 30-year-old patient was found fi tting in bed

(Fig. 4.18.1).

Fig. 4.18.1

Fig. 4.18.2

Fig. 4.18.3

Ideal Summary

This is a single noncontrast axial CT image through the brain. There are multiple tiny foci of calcifi cation along the sulcal spaces over both cerebral convexities and parasagittal region (Fig. 4.18.1, arrows). I can- not see any signs of acute haemorrhage or a space- occupying lesion. The fi ndings are nonspecifi c and may be related to previous infection or infl ammation. I would like to review the remainder of the series and ask if any old images are available for comparison. I would take the case forward by arranging for an MRI.

These are MR images from the same patient

(Figs. 4.18.2 and 4.18.3).

These are axial T2-weighted and postcon- trast T1-weighted MR sequences. On the T2- weighted image, there are multiple T2 hypo- intense lesions in a similar distribution to the CT

(Fig. 4.18.2, arrows), with adjacent subcortical white matter T2 high signal change. The post- contrast image shows several possible enhancing

RZ Sidhu_9783131662910_2013_Section 4.indd 172

4.18 Neurocysticercosis

lesions, one of which is ovoid in the left frontal lobe (Fig. 4.18.3, arrow). Low signal is seen within each of

these lesions. I would like to compare this with the precontrast T1 sequence to confi rm enhancement. The appearances are typical of neurocysticercosis, and the combination of the CT and MRI suggests these are lesions in diff erent stages, both vesicular and calcifi ed. I would suggest follow-up imaging following initiation of appropriate treatment to assess response.

Examination Tips

Neurocysticercosis is most commonly found in the subarachnoid spaces of the convexities. T1-weighted and fl uid-attenuated inversion reco-

very sequences may be helpful in the detection of intraventricular cysts.

Gradient-echo sequences may be employed to identify a calcifi ed scolex.

Look for complications:

•

Hydrocephalus

•

Meningitis.

Diff erential Diagnosis

The appearances are typical of neurocysticercosis. The diff erential diagnosis would include fungal micro- abscess and tuberculosis.

Notes

Neurocysticercosis is the most common parasitic infection of the CNS and is caused by the larval

stage of the pork tapeworm Taenia solium. The most frequent clinical manifestations include seizures, focal neurological defi cits, and headache. Imaging appearances vary according to the stage

in the life cycle of the parasite. The live larvae appears as a hypodense cyst at the grey–white junction, with the scolex represented by an eccen- tric hyperdense nodule—“cyst with a dot.” As the larvae die, there is formation of a granuloma, which causes breakdown of the blood–brain barrier, resulting in contrast enhancement and surrounding oedema. Finally, once the larvae are dead, the cysts and scolices appear as shrunken, densely calcifi ed lesions.

In 20 to 50% of patients, the lesion is solitary. When multiple, lesions are commonly seen at dif- ferent stages in the same patient.

MRI is more sensitive than CT, but CT is superior when demonstrating calcifi cation. A reasonable approach is initially to investigate with a CT brain and serological tests. If the CT is inconclusive in the setting of high clinical suspicion, MRI may help identify small lesions and visualise the scoli- ces. Identifi cation of the scolex is the only pathog- nomonic radiological fi nding.

There are characteristic plain radiographic fi n- dings of multiple, elongated, “cigar-shaped” calcifi cations in the skeletal muscles, and thus a radiograph of the soft tissues of the thigh can also confi rm the diagnosis of intracranial neurocysticercosis.

Bibliography

Rahalkar MD, Shetty DD, Kelkar AB, Kelkar AA, Kinare AS, Ambardekar ST. The many faces of cysticercosis. Clin Radiol 2000;55(9):668–674

174

4 Neurological Imaging

4.19 Spontaneous Intracranial Haemorrhage

Clinical History

A 55-year-old man was found unconscious

(Figs. 4.19.1 and 4.19.2).

Ideal Summary

These are axial unenhanced CT images through the brain. There is an area of high density centred on the right thalamus and lentiform nucleus, in keeping with acute haemorrhage. There is haemorrhagic extension into the lateral, third, and fourth ventricles and sub- arachnoid space, with associated hydrocephalus and some midline shift to the left. In addition, there is periventricular and deep white matter low attenua- tion most likely to represent transependymal inter- stitial oedema and almost complete eff acement of the basal cisterns. The distribution of blood is typical of an acute hypertensive haemorrhage, and I would like to know if the patient is hypertensive. I would recommend an urgent neurosurgical referral in view of the intraventricular extension and hydrocephalus.

Examination Tips

Hypertensive haemorrhage has a propensity for the areas of brain in close proximity to the higher vascular pressures of the circle of Willis, such as the basal ganglia, thalamus, pons, and cerebellum. Remember that patients under 45 years of age

may harbour an underlying vascular lesion or venous thrombosis, and hypertension in a younger age group may be related to illicit drug use, for example of cocaine.

Often the cause of a lobar haemorrhage is diffi cult to establish, and further imaging may be helpful if there is a clinical suspicion: MR for an underlying neoplasm or amyloid angiopathy; CT angiogram for the presence of an aneurysm.

Diff erential Diagnosis

Amyloid angiopathy:

•

The patient is usually over the age of 65 years and normotensive

•

Predominantly lobar in distribution, parti- cularly in the parietal and occipital lobes and sparing the deep subcortical regions

•

Presence of T2 high signal in the white matter and microhaemorrhages on T2* gradient-echo imaging is suggestive of underlying amyloid angiopathy

•

Can coexist with hypertensive microangiopathy.

Fig. 4.19.1

Fig. 4.19.2

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