The Neuroradiology Journal

The medial lemniscus is part of the main somatosensory pathways ascending within the brainstem. It is formed by the heavily myelinated axons of the second order neurones of the dorsal column nuclei. This pathway ascends through the rostral medulla, pons and mesencephalon to finally terminate by synapsing with third order neurones in the ventral posterior nucleus of the thalamus. The medial lemniscus conveys proprioception and fine tactile discrimination as part of the somatosensory system. Conventional MRI studies of the brainstem have been relatively poor in demonstrating these fibre pathways. Diffusion tensor imaging and tractography may demostrated fibre pathways in the brainstem. These techniques do however suffer from relatively poor spatial resolution and some degree of image distortion – especially if based on echo planar imaging techniques. Knowledge of the anatomical relationships of the medial lemniscus is important for the understanding of clinical manifestations of disease processes affecting the somatosensory pathways and also to demonstrate important adjacent structures. Specifically, the pedunculopontine nucleus (PPN) lies in close anatomical relationship to the medial lemniscus and the decussation of the superior cerebellar peduncle. This nucleus is a promising target for deep brain stimulator placement for alleviation of non-dopamine responsive dystonias. Six healthy male volunteers (mean age 33 years) were imaged at 3 Tesla. Imaging protocols consisted of thin section, high resolution, fat suppressed T1-weighted sequences as well as thin section, high isotropic resolution diffusion tensor imaging (DTI), which was analysed to generate colour fractional anisotropy (FA) maps. These were correlated with the fat suppressed T1 weighted images. In all volunteers the medial lemniscus was seen as a pair of bands of low signal on axial, high resolution, fat suppressed T1-weighted images. They were indentified through the upper medulla, pons and mesencephalon. They correlated well with the head to foot orientated fibres on the colour FA maps generated from the DTI data. This study of normal volunteers has illustrated the value of high resolution, fat suppressed T1-weighted images in demonstrating the anatomy of the heavily myelinated medial lemniscus within the brainstem. These high resolution images with good spatial accuracy can potentially be used to aid the localisation of other nuclei, such as the PPN.

The authors reviewed the diffusion tensor imaging (DTI) and tractography (DTT) of the normal brainstem and cerebellar white matter in normal volunteers, correlating it with structural magnetic resonance (MR) imaging and DTI data obtained in patients evaluated in our institution with movement disorders, including multisystem atrophy (MSA), spinocerebellar ataxia (SCA), progressive supra-nuclear palsy (PSP) and idiopathic Parkinson's disease (PD). DTI and tractography data demonstrated major white-matter fibers within the brain stem and cerebellum, including cortico-spinal tracts, transverse pontine fibers, medial lemniscus and cerebellar peduncles. Visualization of selective degeneration of these individual fibre tracts with DTI, in our cases, added qualitative data to the differential diagnosis of movement disorders.

This study investigated diffusion abnormalities in the parts of corpus callosum (CC) of patients with Alzheimer's disease (AD) using diffusion tensor magnetic resonance imaging (DT-MRI). Twenty-one patients with AD and 20 healthy volunteers participated in the study. MRI was performed with a 1.5 T system. Conventional MR images and diffusion tensor images were obtained for all participants. We divided the CC into three parts as rostrum, body and splenium. The apparent diffusion coefficiency (ADC) and fractional anisotropy (FA) were measured in all parts. FA values for the CC were lower in AD patients than the values of controls. In AD patients the lowest values were found in the rostrum of the CC and CC body FA values were also lower than the splenium, but the difference did not reach statistical significance. DT-MRI is a promising technique to investigate microstructural changes in white matter regions in AD. Early detection of the disease has been increasingly studied in AD. Further studies with larger populations are needed to confirm the role of diffusion tensor imaging in the evaluation of memory impairment.

Ischemic stroke in young people is an unexpected event due to a wider variety of causes compared to the older population. This study highlights the increasing role of neuroimaging in the diagnosis, prognosis and treatment of young stroke patients. Thirty young adult patients (age range, 15–45 years) with acute ischemic stroke diagnosis were retrospectively included and studied at our institution during 2009. The mean age of patients was 35 years and 50% were men. The stroke etiology was established in 86% of cases (n=26), 7% (n=2) were due to atherosclerosis of the main vessels, 10% (n=3) were related to cardioembolism, 27% (n=8) were due to arterial dissection and 43% (n=13) responded to miscellaneous etiologies. The cause remained unexplained in 14% (n=4) of cases. The aims of neuroimaging in the challenging study of young stroke patients are to confirm the ischemic nature of the lesion, to determine its location, and to verify the patency of major neck and intracranial arteries. Both MRI and MSCT offer the best sensitivity and spatial resolution.

A3243G mutation is associated with several mitochondrial disorders, MELAS syndrome being the most common. Polymicrogyrias constitute an extensive group of malformations of cortical development due to abnormal cortical organization. The association between MELAS/A3243G mutation and polymicrogyria is extremely rare; in 18 years of investigation regarding A3243G mutation and related disorders only one case has been reported. We describe a female patient with proven MELAS/A3243G mutation, developmental delay and mild left hemiparesis in whom MRI showed extensive bilateral polymicrogyria. The association of these two disorders and their possible relation are discussed.

Infantile neuroaxonal dystrophy (INAD) is a rare autosomal recessive neurodegenerative disorder characterized by infantile onset and rapid progression of psychomotor regression and hypotonia evolving into spasticity. The neuroradiologic hallmark of the disease is represented by progressive cerebellar atrophy. Prior to the discovery of mutations in the PLA2G6 gene in family with INAD, the clinical diagnosis of the disease had been confirmed by the presence of spheroid bodies (SB) in a peripheral nerve biopsy. Various studies have found that some patients with mutations lacked SB and some without mutations had SB, indicating incomplete detection using either pathologic or molecular methods ⁷. This, together with the observation that the spectrum of clinical features associated with mutations in PLA2G6 is broader than previously described, has increased the usefulness of Magnetic Resonance (MR) in INAD diagnosis, particularly in the frequent occurrence of atypical cases, especially in the early stages of the disease. We retrospectively reviewed the MR studies of eight patients in whom clinical and imaging onset met the typical criteria for INAD. Their clinical and MR imaging (MRI) onset and follow-up were evaluated together with the neuroradiological findings reported in the literature in order to identify MRI features useful in differentiating INAD from other diseases with similar clinical onset and to discuss which of them are the most important, thus suggesting INAD diagnosis. Our contribution included the use of Proton Spectroscopy (¹H-MR), diffusion weighted MR imaging (DWI) and diffusion tensor imaging (DTI) in the follow-up of seven of the eight patients. The literature reviewed included attempts to correlate clinical and MR data with the genotype in the group of patients carrying PLA2G6 mutations. From the limited and inhomogeneous cohort of patients included in our study, a correlation between the MR features, phenotype and genotype was not exhaustive.

Nonketotic hyperglycemia (NKH) is a clinical syndrome consisting of hyperglycemia, hyperosmolality and intracellular dehydration but not ketoacidosis. This prospective study evaluated the clinical and magnetic resonance imaging abnormalities in six patients with NKH complicated with simple or complex partial seizures. Subcortical T2 hypointensity rather than hyperintensity together with contrast enhancement was a characteristic feature of seizures associated with NKH. Restricted diffusion on DWI and decreased NAA and/or Choline on MRS studies were also noted.

Progressive supranuclear palsy (PSP) also known as Steele, Richardson and Olszewski disorder is a neurodegenerative brain disease that has no known cause, treatment or cure. PSP has no known geographical, occupational or racial preference and affects brain cells that control walking, balance, mobility, vision, speech and swallowing. Symptoms begin on average in the early 60s, but may start as early as in the 40s: a good history and physical examination support the clinical diagnosis and latency of each feature makes us suspect a probable PSP, an atypical Parkinsonism. The diagnosis of a large number of cases of PSP is missed or delayed: 75% of the patients are never clinically diagnosed by neurologist and in most cases the median interval between onset and diagnosis is three years. Notwithstanding such differences in clinical presentation, there remains an overlap in symptoms making the differential diagnosis between such neurodegenerative disorders challenging. A few imaging techniques developed to evaluate brain anatomy and function are used extensively to improve the diagnostic accuracy of different forms of Parkinsonism. Noninvasive and safe methods can now document brain structures. Transcranial sonography (TCS) is a very low cost tool to assess the basal ganglia and mesencephalic echogenicity. Conventional magnetic resonance imaging (MRI) is a valuable tool to exclude secondary Parkinsonism. Our purpose is to define characteristic objectively measured imaging markers that point out normal biological processes, and pathogenic processes in PSP. Such markers should be sufficiently sensitive and specific to show the underlying biological disease and the pharmacological responses to therapy.

Amyotrophic lateral sclerosis (ALS) is characterized by progressive upper and lower motor neuron degeneration. A hyperintense signal on T2-weighted images along the corticospinal tract has been reported in patients with confirmed ALS. However, the specificity of this finding is under consideration, since it is also identified in healthy controls. Moreover, the correlation of this finding with disease progression has not yet been established. The purpose of our study is to evaluate the frequency with which this high signal appears in the posterior limb of the internal capsule (PLIC), compare visual with quantitative measurements, and correlate these with the progression of the disease. Our prospective clinical study included 24 patients and 51 healthy volunteers. In the ALS patient group, the diagnosis was established according to the criteria of El Escorial in the revised form of Airlee House. All patients were neurologically examined and underwent diagnostic procedures to exclude other diseases resembling ALS. The initial MRI was performed six months to two years after the onset of symptomatology. All ALS patients were clinically examined regarding their symptoms from the upper and lower motor neurons. Follow-up MRIs were performed in nine out of 24 patients over a period of six months. Signal changes in the PLIC are visually evaluated on FLAIR images, and are classified as distinct, mild or no signal change. Fractional anisotropy (FA) measurements are performed by placing a region of interest (ROI) in the PLIC bilaterally. Both findings are being compared. Mild signal changes were visualized in the PLIC in ten volunteers and seven patients. Distinct T2 FLAIR signal changes were visualized in the PLIC in seven ALS patients. No distinct signal change was visualized in the controls. Moreover this increased T2 FLAIR signal change became more accentuated with disease progress. FA measurements in patients were lower than in age-matched healthy subjects, with a further decrease with disease progression. Our findings indicate that although mild hyperintensity of the PLIC is not pathognomonic for ALS, detection of a distinct PLIC hyperintensity that gradually accentuates might actually be a sign of progressive ALS. This finding is supported by the progressively decreasing FA measurements. Larger numbers of patients need to be included and re-evaluated to obtain statistically significant results.

We investigated the alteration of dopaminergic system in striata of Parkinson's disease (PD) at different stages using positron emission tomography (PET), [¹¹C]2β-carbomethoxy-3β-(4-fluorophenyl)tropane (CFT) for dopamine transporter (DAT), and [¹¹C]raclopride (RAC) for dopamine D₂ receptor (D2R). We studied eight elderly healthy volunteers (Group A), 13 drug naïve patients with PD (Group B), and seven advanced PD patients with mild dyskinesia (Group D). Six patients in Group B were re-examined after antiparkinsonian therapy (Group C). Regions of interest were drawn on the cerebellar hemisphere, head of the caudate nucleus (CN), and anterior (AP) and posterior putamen (PP) in the PET images. We calculated uptake ratio index (URI), asymmetry index (AI) and presynapse-to-postsynapse ratio (PPR) to evaluate dopaminergic function. DAT was smaller in the three PD groups than the Group A. URI of RAC in the PP was significantly larger in Group B than in Groups A and C. AI of CFT in the putamen was larger in the PD groups than in normal subjects, and AI of RAC in the PP was the largest in the Group B. PPRs in the AP and PP were smaller in the three PD groups than in Group A. DAT decreased with disease progression in patients with PD. Binding of RAC was largest in the putamen of drug-naïve PD patients, but the enhanced binding could not be detected in the therapeutic patients with PD because of weak D2R affinity of RAC.

Extrapontine myelinolysis (EPM) and cortical laminar necrosis (CLN) have rarely been reported in association with severe hypernatremia. We describe a patient with EPM associated with CLN following severe hypernatremia due to hypertonic peritoneal lavage after a ruptured hydatid cyst of the liver. Clinical and neuroimaging findings in acute stage and serial brain MRI at two and five month follow-up are discussed in detail.

Superficial siderosis of the central nervous system (CNS) is a rare entity characterized by the deposition of hemosiderin in the leptomeninges. In most cases it is caused by chronic and recurrent bleeding into the subarachnoid space as a subclinical form and for long periods of time. The cases described in the literature are associated with tumors, aneurysms, arteriovenous malformations, changes in post-surgical, traumatic cervical and brachial plexus injuries. However, the cause of bleeding is unclear in 40–50% of cases. This report describes the case of a 38-year-old man with a history of trauma with a complete lesion of the left brachial plexus. The patient presented progressively worsening gait imbalance, bilateral deafness, tinnitus and memory loss over two years. Neurological examination disclosed bilateral hearing loss, left upper limb plegia with atrophy of muscle mass, spastic paraparesis with pyramidal signs and gait ataxia. The analytical/genetic study was consistent with hereditary hemochromatosis. In addition to typical findings of siderosis, MR disclosed pseudomeningocele while CT angiography and angiography revealed an aneurysm of the internal carotid artery. Although rare, we should be aware of superficial siderosis especially in imaging studies in patients with deafness or ataxia and in those with lesions of the brachial plexus. The imaging signals are subtle and can easily go unrecognized. The radiological investigation must be extensive to find the primary cause.

Three elderly patients with, respectively: mild cognitive impairment, severe and progressive neurologic involvement, and focal neurologic deficit, were observed. MRI showed multiple areas of white matter edema, at times partially involving the cortex, in the first two patients, and a single area in the third. Treatment with steroids determined the disappearance of the lesions and clinical amelioration. The key to the diagnosis of cerebral amyloid angiopathy-related inflammation (CAA-ri) was the demonstration, with appropriate MRI sequences, of microbleeds consistent with cerebral amyloid angiopathy (CAA). This diagnosis was supported by genetic analysis of APOE with demonstration of ε4/ε4 genotype, found in about 80% of CAA patients who develop inflammatory changes. In the appropriate clinical setting, MRI demonstration of microbleeds supported by results of genetic analysis of APOE may strongly support the diagnosis of CAA-ri thus avoiding cerebral biopsy.

We describe an unusual presentation of posterior reversible encephalopathy syndrome (PRES) with predominant posterior fossa edema, causing ascending transtentorial herniation, tonsillar herniation, and obstructive hydrocephalus. MR imaging with additional MR spectroscopy and MR perfusion helped discriminate PRES from infiltrative tumor, and supported the pathogenesis of hydrostatic edema. Infusion of an antihypertensive drug was promptly administered. Diversion of cerebrospinal fluid by ventriculostomy was subsequently performed. However, the patient developed thalamic hemorrhage and secondary intraventricular hemorrhage with contralateral hemiparesis. Awareness of this rare cause of obstructive hydrocephalus with aggressive treatment of high blood pressure may help obviate the need of ventriculostomy and may prevent the hemorrhagic complication.

The most important symptoms associated with schizophrenia are affective flattening, decreased expression of emotions, anhedonia and social isolation. The purpose of the present study was to investigate the neural response to disgusting and pleasant visual stimuli in healthy subjects and in patients with first-episode schizophrenia. Twelve subjects in the first episode of schizophrenia (DSM-IV-R, APA, 2000) with a normal IQ and 12 healthy volunteers selected for age and education underwent functional magnetic resonance imaging (fMRI) during observation of pleasant and disgusting visual stimuli. Analysis showed that in healthy subjects, the prefrontal cortex and limbic areas are activated in response to pleasant and disgusting visual stimuli, whereas this does not occur in subjects with schizophrenia since the first episode of illness.

Idiopathic intracranial hypertension (IIH) is characterized by an increased intracranial pressure in the absence of expansive lesions or cerebrospinal fluid (CSF) circulation obstructions. Its physiopathology is still not fully understood. The diagnosis is currently established on clinical grounds (Dandy criteria) along with an invasive measurement of CSF dynamic parameters through the infusion test. This study compares the invasive pressure measurements with the biomechanical CSF parameters derived from a phase-contrast MR protocol to evaluate the accuracy and reliability of the phase-contrast MR protocol.

The treatment for acute stroke is evolving and we present the initial results of 18 patients presenting to our institution over a period of eight months with acute stoke where CTA confirmed the presence of a thrombus. These patients were resistant to IV rtPA and underwent partial to complete clot retrieval with IA thrombolysis or in conjunction with mechanical thrombectomy. 13 of the 18 patients underwent mechanical thrombectomy and Solitaire AB device was used in 12 of these patients. Efficacy was assessed radiologically by post-treatment thrombolysis in myocardial infarction (TIMI) scores and clinically by a 30-day Modified Rankin Scale (MRS) score A TIMI score of 3 was achieved in 91% of patients undergoing mechanical thrombectomy with Solitaire AB device. 61% of our patient group had a discharge MRS of ≤ 2.

Cerebral venous infarct is considered to be rare (0–5% of all strokes). In some cases venous infarcts with no specific signs on conventional CT or MR study are not diagnosed due to incomplete examination. A venous infarct more often (63%) than an arterial (15%) infarct is accompanied by hemorrhage (primary or secondary in the early period) and a high risk of hemorrhage should be a contraindication to intravenous thrombolysis. Consequently, the definition of the kind of a stroke should lead to different therapeutic tactics. Using MR and CT angiographic and perfusion techniques in the urgent examination of patients with an infarct, considering time necessary for the “time window”, can lead to exact diagnosis and fewer complications.

To illustrate the imaging features of fibromuscular dysplasia (FMD) in this rare presumptive case of FMD in a sixteen year old male with intracranial features only and highlight it as an important cause of stroke in the young. FMD is a non-atheroscelerotic, non-inflammatory vasculopathic arterial disease affecting large and medium size vessels of unknown aetiology. It is a rare cause of paediatric stroke and strokes in young adults. This is a pictorial presentation of an unusual presumptive case of fibromuscular dysplasia (FMD) affecting the middle cerebral artery in a sixteen year old male with classic Digital Subtraction Angiography (DSA) findings. The focal neurological findings and pattern seen on sequential brain scans clearly associates the presence of this vascular lesion to cerebral infarction. Classic imaging findings of the epidemiology, pathology and radiological appearance of FMD are discussed. Emphasis is placed on the patient's imaging presentations including DSA. FMD is a vascular dysplasia that typical affects the renal vasculature and commonly the extracranial internal carotid artery. When a young adult or child presents with stroke FMD should be considered and is more likely to have intracranial features.

We describe a patient who suffered reversible hypoxic brain injury. The initial MRI taken 3.5 hours after asphyxiation showed an abnormal lesion on DWI, but he recovered completely from coma. The presence of cytotoxic edema in the acute stage may not necessarily indicate a poor prognosis.

Disorders of consciousness have been related to different disconnection patterns as assessed by neuroimaging tools such as PET or fMRI. In this report, we use resting-state functional MRI acquisition and a functional connectivity analysis by graph of brain networks, to investigate the global residual connection pattern in a patient with consciousness disorders following post-anoxic injury. We then compare this pattern with those of a group of twenty controls. We observed that the patient's graph presents multiple disconnections in primary areas and in high-order associative areas. This pattern is consistent with a vegetative state, as reported by other groups. Further, the informations conveyed by this approach are consistent with those provided by PET, fMRI and EP. This new approach presents a very strong potential for diagnosis for consciousness disorder patients since it is applicable very early after the insult.

Epilepsy is more than a grey-matter disorder affecting large white matter connections of the brain with seizure generation and propagation. The mechanism for such changes remains unclear. The purpose of this study was to investigate the microstructural changes in the corpus callosum in temporal lobe epilepsy (TLE) patients and whether these abnormalities are related to antiepileptic drug (AED) therapy. Ten TLE patients receiving AED therapy, ten TLE patients with no therapy and ten controls were included in the study. The regions of interest in the corpus callosum were outlined to each Witelson region (WR). Fractional anisotrophy (FA), apparent diffusion coefficient (ADC), three main diffusivity values (λ1, λ2, λ3) and tractography were acquired from each WR. DTI indices of these tracts and each WR were compared between the three subject groups and correlates examined with clinical variables that included duration of epilepsy, gender, AED type and AED therapy exposure. In TLE subjects with receiving AED therapy significantly (p<0.05) decreased FA and increased ADC values of corpus callosum were obtained when compared to the other groups. There was no significant relationship between AED type and DTI indices. Analysis of eigen values in the splenium of corpus callosum (WR7) showed λ1 values were significantly decreased in relation to AED medication duration (p<0.05). FA values of rostrum and corpus showed a reduction with duration of epilepsy. TLE is associated with abnormal integrity of corpus callosum white matter tracts. AED therapy may cause additional damage on secondary degeneration and medication time effects especially on the splenium of corpus callosum.