Motor neuron disease mimics in practice: a case series.

In the majority of cases of motor neuron disease (MND), diagnosis is clinical and unambiguous. However, given the gravity of the diagnosis, it is crucial that treatable mimics are differentiated accurately. We present three cases referred to our clinic with possible MND with unusual features that led to an alternative diagnosis. (1) A middle-aged man with swallowing, then speech problems and foot drop. Tongue movements were slow and electromyography (EMG) showed fibrillations/positive sharp waves. Following investigation, a tonsillar tumour involving the tongue root was identified, and the foot drop improved, suggesting unrelated common peroneal nerve palsy (related to weight loss) or lumbar radiculopathy. (2) An elderly man presenting with progressive unilateral leg weakness and localised fasciculations on EMG. Following investigation, a high-grade brain glioma was diagnosed. (3) An elderly woman presenting with progressive quadriparesis over 18 months with fibrillations and chronic denervation on EMG. Symmetrical weakness and short duration response to immunotherapy led to further serological investigation and a diagnosis of anti-GD1a motor neuropathy. She was treated successfully with intravenous immunoglobulin, cyclophosphamide and rituximab and is now in remission.

Computer-aided diagnosis for (123I)FP-CIT imaging: impact on clinical reporting.

BACKGROUND: For (123I)FP-CIT imaging, a number of algorithms have shown high performance in distinguishing normal patient images from those with disease, but none have yet been tested as part of reporting workflows. This study aims to evaluate the impact on reporters' performance of a computer-aided diagnosis (CADx) tool developed from established machine learning technology. Three experienced (123I)FP-CIT reporters (two radiologists and one clinical scientist) were asked to visually score 155 reconstructed clinical and research images on a 5-point diagnostic confidence scale (read 1). Once completed, the process was then repeated (read 2). Immediately after submitting each image score for a second time, the CADx system output was displayed to reporters alongside the image data. With this information available, the reporters submitted a score for the third time (read 3). Comparisons between reads 1 and 2 provided evidence of intra-operator reliability, and differences between reads 2 and 3 showed the impact of the CADx. RESULTS: The performance of all reporters demonstrated a degree of variability when analysing images through visual analysis alone. However, inclusion of CADx improved consistency between reporters, for both clinical and research data. The introduction of CADx increased the accuracy of the radiologists when reporting (unfamiliar) research images but had less impact on the clinical scientist and caused no significant change in accuracy for the clinical data. CONCLUSIONS: The outcomes for this study indicate the value of CADx as a diagnostic aid in the clinic and encourage future development for more refined incorporation into clinical practice.

Ruptured intracranial dermoid cysts: a pictorial review.

Intracranial dermoid cysts are rare, benign, congenital, slow-growing cystic lesions. They are composed of mature squamous epithelium and can contain apocrine, eccrine, and sebaceous glands as well as other exodermal structures. Rupture of intracranial dermoid cysts is a relatively uncommon phenomenon but can cause more serious complications such as chemical meningitis, vasospasm, and cerebral infarction. Understanding of the appearance of both unruptured and ruptured dermoid cysts on computed tomography and MRI, especially awareness of existing low signal "blooming artefacts" on certain sequences, aids diagnosis and referral to the proper specialty for appropriate treatment.

'Low grade glioma': an update for radiologists.

With the recent publication of a new World Health Organization brain tumour classification that reflects increased understanding of glioma tumour genetics, there is a need for radiologists to understand the changes and their implications for patient management. There has also been an increasing trend for adopting earlier, more aggressive surgical approaches to low-grade glioma (LGG) treatment. We will summarize these changes, give some context to the increased role of tumour genetics and discuss the associated implications of their adoption for radiologists. We will discuss the earlier and more radical surgical resection of LGG and what it means for patients undergoing imaging.

Clinical Experience with Pedunculopontine Nucleus Stimulation in Conditions with Nigrostriatal Disconnection.

BACKGROUND: The pedunculopontine nucleus (PPN) is a part of the mesencephalic locomotor region and, in recent years, it has been considered a new surgical target for deep brain stimulation (DBS) for movement disorders including atypical parkinsonian syndromes such as progressive supranuclear palsy (PSP) and multiple system atrophy. Involvement of the PPN may play an important role in gait impairment in these disorders and the development of PPN DBS could potentially provide treatment for this disabling problem. However, the role of the PPN and the specific pathways involved in gait control and other motor functions are poorly understood. METHODS: We present a chronological account of our group's experience in the use of PPN DBS. This entails the treatment of four patients with disabling movement disorders who all exhibited either marked damage or disconnection of the nigro-striatal pathway. RESULTS: Within our series, the results were variable in that 2 of the 4 patients benefited greatly from DBS but the other 2 did not. CONCLUSIONS: Our findings suggest that in carefully selected patients, PPN DBS can potentially alleviate symptoms due to dopaminergic striatal inactivity; symptoms that are typically resistant to stimulation of other subcortical targets used for parkinsonian syndromes and movement disorders.

A review of pathologies associated with high T1W signal intensity in the basal ganglia on Magnetic Resonance Imaging.

With several functions and a fundamental influence over cognition and motor functions, the basal ganglia are the cohesive centre of the brain. There are several conditions which affect the basal ganglia and these have various clinical and radiological manifestations. Nevertheless, on magnetic resonance imaging there is a limited differential diagnosis for those conditions presenting with T1 weighted spin echo hyperintensity within the central nervous system in general and the basal ganglia in particular. The aim of our review is to explore some of these basal ganglia pathologies and provide image illustrations.

Preservation of passive constructions in a patient with primary progressive aphasia.

Research into agrammatic comprehension in English has described a pattern of impaired understanding of passives and retained ability on active constructions. Some accounts of this dissociation predict that patients who are unable to comprehend actives will also be impaired in the comprehension of passives. We report the case of a man with primary progressive aphasia (PPA) (WR), whose comprehension was at chance on active sentences, but at ceiling on passives. In a series of reversible sentence comprehension tests WR displayed difficulties with active transitives and truncated actives with an auxiliary. In passive sentences, he displayed sensitivity to the agent marker by, as well as the passive morphology of the verb. This pattern of dissociation challenges current theories of agrammatic comprehension. We explore explanations based on the distinction between morphological and configurational cues, as well as on the semantic and discourse related differences between active and passive constructions.

Complete abolition of reading and writing ability with a third ventricle colloid cyst: implications for surgical intervention and proposed neural substrates of visual recognition and visual imaging ability.

We report a rare case of a patient unable to read (alexic) and write (agraphic) after a mild head injury. He had preserved speech and comprehension, could spell aloud, identify words spelt aloud and copy letter features. He was unable to visualise letters but showed no problems with digits. Neuropsychological testing revealed general visual memory, processing speed and imaging deficits. Imaging data revealed an 8 mm colloid cyst of the third ventricle that splayed the fornix. Little is known about functions mediated by fornical connectivity, but this region is thought to contribute to memory recall. Other regions thought to mediate letter recognition and letter imagery, visual word form area and visual pathways were intact. We remediated reading and writing by multimodal letter retraining. The study raises issues about the neural substrates of reading, role of fornical tracts to selective memory in the absence of other pathology, and effective remediation strategies for selective functional deficits.

Differentiating core and co-opted mechanisms in calculation: the neuroimaging of calculation in aphasia.

The role of language in exact calculation is the subject of debate. Some behavioral and functional neuroimaging investigations of healthy participants suggest that calculation requires language resources. However, there are also reports of individuals with severe aphasic language impairment who retain calculation ability. One possibility in resolving these discordant findings is that the neural basis of calculation has undergone significant reorganization in aphasic calculators. Using fMRI, we examined brain activations associated with exact addition and subtraction in two patients with severe agrammatic aphasia and retained calculation ability. Behavior and brain activations during two-digit addition and subtraction were compared to those of a group of 11 healthy, age-matched controls. Behavioral results confirmed that both patients retained calculation ability. Imaging findings revealed individual differences in processing, but also a similar activation pattern across patients and controls in bilateral parietal cortices. Patients differed from controls in small areas of increased activation in peri-lesional regions, a shift from left fronto-temporal activation to the contralateral region, and increased activations in bilateral superior parietal regions. Our results suggest that bilateral parietal cortex represents the core of the calculation network and, while healthy controls may recruit language resources to support calculation, these mechanisms are not mandatory in adult cognition.

Bilateral Homonymous Hemianopia with Sparing of the Vertical Meridian.

A 19-year-old woman, who was 16 weeks post partum, collapsed with loss of consciousness. Following awakening she suffered abrupt loss of vision. Partial recovery occurred, although she has been left with bilateral homonymous hemianopia with sparing of vision just to the left of the vertical meridian. Magnetic resonance imaging demonstrated bilateral occipital infarcts, sparing the lips of the calcarine sulcus on the right. This is compatible with our expectation that the vertical meridian of the retinotopic map is represented at the superior and inferior lips of the calcarine sulcus.

Restricted diffusion in Wallerian degeneration of the middle cerebellar peduncles following pontine infarction.

BACKGROUND: Acute Wallerian degeneration following infarction has been show to result in areas of restricted diffusion within the brain. Very few reports describe this appearance in middle cerebellar peduncles. CASE REPORT: A 37 year old woman was admitted to hospital following sudden collapse and was subsequently found to have a pontine infarct. The complex clinical course resulted in MR imaging including DWI at day 4, 9 and 23 after the initial presentation. The cerebellar peduncles were normal when imaged on day 4 and 9. At day 23, symmetrical high T2 signal was seen in both cerebellar peduncles. The DWI illustrated high signal with corresponding low signal on the ADC map consistent with restricted diffusion. We discuss why this appearance is in keeping with Wallerian degeneration and also describe the fibre pathways involved. CONCLUSIONS: Symmetrical high signal with restricted diffusion in the middle cerebellar peduncles following a pontine lesion is almost certainly attributable to Wallerian degeneration and should not be mistaken for a new ischaemia.

Antibody-negative neuromyelitis optica with heavy B-cell infiltration.

There are several distinct clinical phenotypes of inflammatory demyelinating diseases of the central nervous system. In classical multiple sclerosis (MS) there are varied pathological patterns, possibly with differences in pathogenesis. Neuromyelitis optica (NMO) is often associated with a specific antibody, suggesting a distinct pathogenesis. We report a case of a young Caucasian male who presented with right hemiparesis secondary to a left fronto-parietal inflammatory brain lesion, which improved over years leaving minimal deficit. Seventeen years later he re-presented with a progressive tetraparesis secondary to cervical myelitis that did not respond to treatment. The NMO antibody was not detected and neuropathological examination was unusual with evidence of a persistent B-cell inflammatory response in the cord. Although having some of the clinical features of NMO, this case presented novel clinico-pathological features that do not easily fit into current MS subtypes.

Effects of sex and age on regional prefrontal brain volume in two human cohorts.

This study examined interactive effects of sex and age on prefrontal brain anatomy in humans. It specifically targeted ranges of the adult life span and regions of cortex that previously showed male-female differences. Participants were 68 healthy human males and females aged 20-72 years. Data collection and analysis were conducted in parallel across two cohorts (laboratories) to investigate reproducibility of effects in relation to sex and age. Volumes for four regional prefrontal subfields per hemisphere were obtained from high-resolution MRI. Regional sex by age interactions were replicated across cohorts. In men, age effects were greatest in medial prefrontal volume, with decreases in dorsal medial and orbital medial regions. In women, age-related changes in medial prefrontal regions were limited to the dorsal volume, with additional decreases observed in lateral subfields. Cohort and Cohort x Age effects in total brain and total prefrontal volume were linked to a combination of methodological and sampling-related factors. Findings indicated that neuroanatomical changes throughout adulthood unfold along different time scales in men and women. Results also showed that sex differences in ageing localized to medial prefrontal regions were particularly robust to variation across cohorts.