The Neuroradiology Journal

Neural organization of cerebral activity in adult and child can be investigated by means of MRI with fMRI and DTI: MRI with fMRI analyses cortical haemodynamic responses correlated to neuronal activity, whereas DTI describes the spatial orientations of the white matter fibres. The fMRI patterns of cortical activity in children more than eight years old overlap the anatomical localization in adults except for the frontal and posterior parietal cortical areas, where BOLD responses in children are often difficult to arouse. This confirms what is currently known: myelin maturation is complete in these areas only in young adulthood. In neonates and young children, depending on the higher cortical cell concentration than adults and the increase in synaptic density up to the age of four-eight years, signal changes detected by BOLD may vary drastically. BOLD signal amplitude may be lower than that found in adults due to the reduced dynamic range during haemodynamic responses, or negative due to the local increase in HbR not fully compensated by the rise in CBF. The administration of sedatives or anaesthesia in children to perform MR scans can influence the BOLD signal: signal amplitude could decrease dramatically and the activated areas could be smaller in extension, indicating a fundamental role of the level of consciousness. BOLD signal analysis can supply useful data on the maturation processes of myelin and the cerebral cortex.

Diffusion tensor imaging (DTI), is a new MR-based technique allowing, in-vivo, the assessment of the water diffusive transport in cerebral tissues, depending on the molecular and biochemical environment. Over the past decade, DTI has become an indispensable part of the MR evaluation of pediatric brain in the clinical practice. Quantitative analysis of fractional anisotropy (FA) and apparent diffusion coefficient (ADC), the two most common indices used to describe the diffusion characteristics, helps the comprehension of the childhood brain maturation and enables the early detection of several brain diseases. DTI also allows us to look at anisotropic diffusion within white matter tracts. To better demonstrate the location and orientation of the white matter tracts, new and/or more sophisticated methods such as Color-Encoded Map and Fiber Tracking have been proposed. We review the theoretical background of DT-MRI, the modality of its data acquisition and processing and some of its commonest applications, particularly in Pediatric Neuroradiology.

Craniosynostosis, a skull growth disorder due to premature fusion of one or more sutures, is a common clinical problem requiring the attention of many specialists. In simple craniosynostosis (stenosis of a single suture) symptoms are usually mild: signs of intracranial hypertension, mental deficiency, visual or hearing problema are rare, whereas learning disorders or aesthetic and psychological problema are more common. Considering the data in the literature, we analyze the clinical presentation of the main forms of simple craniosynostosis (scaphocephaly, trigonocephaly, brachycephaly, plagiocephaly), their assessment, when measuring intracranial pressure can be useful and whether surgery affects late cognitive outcome.

After the “Back to Sleep” campaign, promoted in 1992 by the American Academy of Paediatrics to prevent the Sudden Infant Death Syndrome (SIDS), it was recommended to place babies in a supine sleeping position. The incidence of SIDS has fallen dramatically since 1992, whereas there has been a major increase in the incidence of occipital plagiocephaly (OP). We report the data relative to the OP cases observed in the Paediatric Department of Padua Hospital between 1998 and 2003. 122 (63%) of the 194 cases of craniosynostosis observed presented OP. The 64 children that took part to the study were contacted and underwent neurological examination with an evaluation of skull shape and previous radiograms. We proposed to parents a questionnaire to define the risk factors and estimate the skull deformity over time. 58 of the 64 children presented positional plagiocephaly (PP), six had synostotic plagiocephaly (SP). Since 1998 there has been a progressive increase in cases of PP. There is a male prevalence (65%), but no side prevalence. Firstborns accounted for 33 (51%), whereas 11 were preterm infants (17%). 82% had a gestational age between the 38^th and 40^th week. The mean value of the Apgar Index was 8 at the first minute and 9 at the 5^th minute. At birth the clinical presentation was: occipital flattening already present at birth in 23 children, preferential head orientation in 18, congenital torticollis in 12, ear asymmetry in 12, frontal bossing in ten. We noticed a mild developmental delay in 8 children (13%). The maximum degree of cranial asymmetry was observed in two peaks in cases of PP: at the third and fourth months (34 cases) and then at the sixth and seventh months (13 cases). The SP presented a progressive exacerbation of the deformity until surgery (done at the sixth to seventh months). PP improved by hygienic postural norms in six months; only three patients required surgery for aesthetic reasons. We observed a strict correlation between side of flattening and sleep head position (χ² test, p-value=2,256e-09) and a higher degree of occipital flattening at birth in patients with associated congenital torticollis (Mann-Whitney test, p-value=0.002744). In conclusion, OP is a common condition but essentially benign; it does not cause medical consequences but aesthetic problems. It is necessary to recognize the mild deformity in the newborns so as to intervene early with hygienic postural norms that can correct the asymmetry. The diagnosis is largely clinical and only in case of doubt are radiological examinations required (ultrasonography for sutures, 3D CT scans).

The low incidence (2.6 cases in 100,000) of cerebrovascular disease in paediatric patients compared with the adult population makes it a diagnostic challenge. Etiological factors have changed over time: whereas in the past bacterial meningitis was the most frequent cause, heart disease, haematological disorders, vasculopathy and viral infections have now become the most common. Haemorrhagic stroke is most frequently due to arteriovenous malformations (AVMs), cavernous angioma, haematological disorders and intracranial aneurysms. Traumatic or fibrodyplastic arterial thrombosis is extremely rare. Venous thrombosis most commonly affects the upper sagittal sinus. In two thirds of cases the cause of stroke remains unknown. For years, symptoms of acute CNS deficits have been studied with computed tomography (CT), especially to rule out haemorrhage. To avoid exposing paediatric patients to ionizing radiation, magnetic resonance imaging (MRI), more sensitive and specific for the identification of acute ischaemic stroke, is currently the first-line diagnostic technique. In particular, diffusion-weighted sequences are capable of early identification of ischaemic areas. Association with perfusion techniques will define the areas at high risk of further damage and to attempt to estimate the final volume of the lesion. MR spectroscopy contributes to the characterization of ischaemic lesions. MR angiography (MRA) has proved to be a noninvasive technique with the same diagnostic effectiveness as conventional angiography for dissections, transient cerebral arteriopathy and moyamoya. The cervical arteries are studied using contrast-enhanced sequences. Conventional angiography remains the technique of choice for the study of small vessels disease and AVMs.

Demyelination is the hallmark of neuroimmune disease. It is caused by a breakdown of myelin already formed, relative sparing of myelin producing oligodendrocytes, neurons and astrocytes, and venous inflammation with perivenous infiltration. The neuroradiological investigation of choice in this setting is magnetic resonance (MR) due to its ability to monitor the neuropathological process. Acute disseminated encephalomyelitis (ADEM), also known as postinfectious or hyperergic encephalomyelitis, disseminated vasculoencephalomyelitis and perivenous encephalitis, is the commonest neuroimmune disorder of childhood. Neuroradiological investigation is highly sensitive for a diagnosis of demyelinating disease. MR is highly sensitive but not specific. Spectroscopy is useful for diagnosis: the reduction in axonal density leads to a decrease in N-acetylaspartate with a concomitant increase in choline and myoinositol due to glial proliferation. Spectroscopic findings positive for a decrease of NAA and an increase in choline during the first episode of demyelinating disease in adolescence are suggestive of an evolution to MS.

Acute disseminated encephalomyelitis (ADEM) is an acute inflammatory disease of the central nervous system (CNS) which is diagnosed more frequently today than in the past, but for which there are no controlled epidemiological data. In children, especially in the first ten years of age, the disease shows a mainly “encephalitic” pattern, albeit with varying clinical features, while in adults ADEM may be more “indolent”, sometimes with an unfavourable prognosis. Although ADEM was considered a monophasic disease until a decade ago, cases characterized by a recurrent-relapsing course have been reported, making the differential diagnosis with multiple sclerosis (MS) more difficult. Due to the wide clinical variability of ADEM, little is known about its etiology or patient predisposition. Prognosis is also difficult, since there are no guidelines as to the choice and length of treatment. For differential diagnosis with MS, careful monitoring not only of clinical findings but also of neuroradiological (MRI), biological (cerebrospinal fluid), and neurophysiological (EEG and EP) data is necessary.

A case of occipital eosinophilic granuloma (EG) presenting as right occipital throbbing headache with a “bump” is reported. Even if cranial X-rays and CT scan showed a typical lytic lesion, to make a definite diagnosis of EG histological examination with immunohistochemical detection of S-100 and CD1a antigens was necessary. A total bone scintigraphy ruled out other bone lesions. Treatment of EG depends on the extent of the disease at the time of diagnosis. When no systemic disease is found some authors suggest “wait and see” management. Twelve months after surgery our patient had no recurrences.

Between 1986 and 2001 radiosurgery was used to treat six glomus jugulare tumours, three of which histologically unverified, in patients aged from 31 to 71 years. One of the unverified tumours showed evidence of hormonal activity. All patients had to undergo repeat radiosurgery at varying times because of tumour re-growth or clinical deterioration. Neurological and neuroradiological follow-up periods ranged from three to 19 years, with an average of 8.3 years. Total target dose averaged 75.5 Gy from a minimum of 36 to a maximum of 117 Gy over targets not exceeding 25 mm in diameter. Technical handling was adjusted each time according to the clinical and neuroradiological results obtained. In accordance with the principle on which this technique is based, the stereotactic system of fixation must be non-invasive and at the same time should be as accurate as the classic Leksell (or other similar) systems. Radiosurgery results were highly positive in all six patients with no complications or side effects being noted in any of them. In keeping with findings reported in the literature, radiosurgery appears to be an attractive neurosurgical application also in cases of glomus jugulare tumours and can certainly be indicated not only for complementary post-surgical treatment but also as an alternative to neurosurgery itself.

Craniofacial vascular malformation (CVM) is a major cosmetic concern and may present as catastrophic situations like bleeding apart from the functional impairment. The treatment of CVM has been very challenging. Till the recent past, surgery was the mainstay of treatment. However, because of the torrential intraoperative haemorrhage and frequent recurrences, embolization has evolved as a major adjunct in treating these lesions. This study evaluated the efficacy of various preoperative embolization techniques in the management of CVM. A total of 94 patients (54 males, 40 females) with an age range from three months to 68 years with a mean of 42.4 years having craniofacial AVM (forehead, face, neck and scalp lesions) were treated with the various embolization techniques: Arterial route with (a) hydrogel only (b) hydrogel and gelfoam (c) gel foam only (d) nbutyl cyanoacrylate (NBCA), Venous route and direct puncture injection of NBCA. The devascularisation achieved with the transarterial route was between 80–95% with particulate agents and 95–100% with NBCA. Direct puncture embolization also resulted in near total devascularisation of the lesion. This resulted in a significant decrease in blood loss at surgery. Cure was obtained in a few patients without the need for surgery. After embolization, almost all the patients had mild pain and subtle increase in the swelling with firmer consistency. The embolization of CVM is an essential adjunct to surgery in most cases and can be curative in a few patients. Hydrogel, PVA and gelfoam are good embolizing agents with NBCA being excellent when used with direct puncture.

Hippocampal Sclerosis (HS) is the most common cause of refractory temporal lobe epilepsy in adults. The aim of our study was to evaluate the diagnostic accuracy of conventional MRI sequences in HS and devise a cost-effective protocol of choice. Forty-eight patients, 26 men and 22 women, aged 16–55 years (mean age 29 years) with seizures refractory to medical treatment were evaluated by MR imaging. Hippocampal formation was assessed by transverse spin-echo (SE) T1-weighted (WI) and fast spin-echo (FSE) T2-WI sequences and by coronal Fluid Attenuated Inversion Recovery (FLAIR) and Inversion Recovery (IR) images. Increased signal intensity in FLAIR (93.2%), hippocampal atrophy (84.8%) and decreased signal intensity in IR images (72.7%) were the most common pathological findings of HS, while loss of the ipsilateral temporal lobe gray/white matter demarcation (66,7%) and amygdala sclerosis (15.1%) were encountered less frequently. FLAIR sequence was found to be more sensitive than FSE T2-WI in detecting HS. Thin coronal images were particularly helpful in assessing hippocampal formation, while IR images were additionally useful for the detection of possible co-existent cortical abnormalities. A brief review of the imaging findings of HS in more recent MR sequences is also made, though emphasizing that conventional SE T1-WI, FSE T2-WI, FLAIR and IR sequences, with a total examination duration of less than eight minutes, provide high sensitivity and specificity in the assessment of HS.

Tumefactive lesions are a rare form of multiple sclerosis (MS) presentation often provoking a diagnostic dilemma with brain tumour or abscess. We describe two cases of tumefactive demyelinating MS plaques and two different approaches. In the first patient the clinical and laboratory findings were consistent with MS, a diagnosis supported by the rapid response to high-dose steroid treatment. On the contrary, atypical clinical, imaging and laboratory findings in our second patient misled us to a diagnosis of a brain tumour. The diagnosis of MS was made after histopathological examination of the excised mass. Both our patients developed a second tumor-like demyelinating mass in the contralateral and almost homologous white matter two years after their first admission to our hospital. A brief review of the imaging diagnostic approach to tumor-like MS plaques and changes appearing in the contralateral and especially in the homologous white matter of MS patients is reported.

Fifty minutes following implantation of a right internal carotid artery stent, left lower extremity paresis developed in a patient despite use of heparin, clopidogrel and aspirin. Immediate angiograms revealed partially thrombosed carotid stent, then tirofiban (a glycoprotein IIb-IIIa receptor inhibitor) was administered intraarterially into the stent. After 15 minutes, complete resolution of the thrombus was detected on repeat angiography. The patient had recovered completely at 30-day follow-up.

A high grade astrocytoma developing following radiotherapy for a medulloblastoma is reported in a six-year-old girl. The latency period was unusually short. The stigmata of Von Recklinghausen's disease in this patient suggest a genetic propensity, though radiation for the primary tumor is considered a more likely predisposing factor in addition to the increased likelihood of development of second malignant tumor in survivors of childhood cancer.

CNS parenchymal metastases are common as is metastatic meningeal involvement. However, the high index of suspicion and contrast enhanced MRI also help in detecting meningeal deposits. We herewith report cases of leptomeningeal deposits in patients with a known primary tumour elsewhere. The importance of gadolinium enhanced MRI is stressed.

Recently, there has been a significant rise in the prevalence of tuberculosis and an increase in the extrapulmonary manifestations worldwide. Diagnosis of extrapulmonary tuberculosis is often difficult. Although a positive chest radiograph or positive tuberculin skin test supports the diagnosis, negative results do not exclude the possibility of extrapulmonary tuberculosis. However, recognition and understanding of the common and uncommon radiologic findings of extrapulmonary tuberculosis can help in diagnosis. Here we describe the value of MRI in demonstration of subtle meningeal pathology in spinal arachnoiditis.

We reviewed clinical and neuroradiological findings in 37 consecutive patients with cervical cord infarction due to vertebral artery dissection diagnosed at our institution from 1996 to 2004. Four patients had clinical and neuroradiological findings consistent with spinal cord ischemia. Three patients had “pencil-like” infarction at C3-C5 level; one patient had an infarction of the anterior horns of the spinal grey matter at C3-C4 level. Symptoms were crural sensory deficit with mild tetraparesis and proximal strength deficit of the arms, respectively. Spinal cord infarction complicated vertebral artery dissection in about 10% of patients of our series. Infarctions involved the most central regions of the spinal cord, with relative sparing of the peripheral white matter tracts. Clinical and MRI pictures were almost typical, and consistent with a hemodynamic mechanism for the lesions. Vertebral artery dissection must be considered in the differential diagnosis in patients with cervical cord infarction.