A widespread visually-sensitive functional network relates to symptoms in essential tremor

Abstract

Essential tremor is a neurological syndrome of heterogeneous pathology and aetiology that is characterized by tremor primarily in the upper extremities. This tremor is commonly hypothesized to be driven by a single or multiple neural oscillator(s) within the cerebello-thalamo-cortical pathway. Several studies have found an association of blood-oxygen level-dependent (BOLD) signal in the cerebello-thalamo-cortical pathway with essential tremor, but there is behavioural evidence that also points to the possibility that the severity of tremor could be influenced by visual feedback. Here, we directly manipulated visual feedback during a functional MRI grip force task in patients with essential tremor and control participants, and hypothesized that an increase in visual feedback would exacerbate tremor in the 4–12 Hz range in essential tremor patients. Further, we hypothesized that this exacerbation of tremor would be associated with dysfunctional changes in BOLD signal and entropy within, and beyond, the cerebello-thalamo-cortical pathway. We found that increases in visual feedback increased tremor in the 4–12 Hz range in essential tremor patients, and this increase in tremor was associated with abnormal changes in BOLD amplitude and entropy in regions within the cerebello-thalamo-motor cortical pathway, and extended to visual and parietal areas. To determine if the tremor severity was associated with single or multiple brain region(s), we conducted a birectional stepwise multiple regression analysis, and found that a widespread functional network extending beyond the cerebello-thalamo-motor cortical pathway was associated with changes in tremor severity measured during the imaging protocol. Further, this same network was associated with clinical tremor severity measured with the Fahn, Tolosa, Marin Tremor Rating Scale, suggesting this network is clinically relevant. Since increased visual feedback also reduced force error, this network was evaluated in relation to force error but the model was not significant, indicating it is associated with force tremor but not force error. This study therefore provides new evidence that a widespread functional network is associated with the severity of tremor in patients with essential tremor measured simultaneously at the hand during functional imaging, and is also associated with the clinical severity of tremor. These findings support the idea that the severity of tremor is exacerbated by increased visual feedback, suggesting that designers of new computing technologies should consider using lower visual feedback levels to reduce tremor in essential tremor.

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Cutaneous infection with paucibacillary Mycobacterium tuberculosis treated successfully with a modified antituberculous drug regimen

Tuberculosis is a serious infection that is increasing in prevalence, affecting many people worldwide. The diagnosis of cutaneous tuberculosis is challenging and requires the correlation of clinical findings with often inconclusive diagnostic testing. Extrapulmonary tuberculosis comprises approximately 10% of all cases of tuberculosis, and cutaneous tuberculosis makes up only a small proportion of these cases. Discussed here is the case of a 61-year-old immunocompetent female with a large cutaneous lesion on her index finger secondary to Mycobacterium tuberculosis. Tissue cultures taken at biopsy were negative; however, empiric antimycobacterial therapy was initiated. The initial regimen was not tolerated, and antituberculous therapy was substituted for moxifloxacin and clarithromycin. The lesion improved significantly with a concurrent improvement in function.

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Maxillary chondrosarcoma mimicking torus palatinus

Description 

An 88-year-old man was referred to the head and neck surgery clinic for investigation of a painless hard palate lesion. The mass had been present for several months and was identified incidentally by the general practitioner. There were no oral or sinonasal symptoms. On examination, a 3x2 cm hard palatal swelling, covered by normal mucosa and resembling a torus palatinus was identified (figure 1). Flexible nasal endoscopy revealed the tumour to involve the floor of the nasal cavity bilaterally, displacing the inferior nasal turbinates. Examination of the neck was normal.

Figure 1

Midline palatal swelling covered by mucosa.

A biopsy was taken, and histological analysis described a welldifferentiated cartilaginous lesion consistent with a grade 1 chondrosarcoma. A CT scan was performed (figure 2). The regional head and neck and regional sarcoma multidisciplinary team meetings recommended surgical management. The patient underwent...

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Intractable hyperemesis gravidarum in a patient with type 1 diabetes

Hyperemesis gravidarum is not uncommon. Its pathogenies is multifactorial but not fully understood. We present a case of a middle class, Caucasian pregnant woman aged 24 years with coexisting type 1 diabetes, who had severe hyperemesis gravidarum from the sixth week of pregnancy and was resistant to all standard and off-the-label treatments raising questions about the pathogenesis of hyperemesis gravidarum. She was managed with a multidisciplinary approach and was supported with total parenteral nutrition till she had an emergency caesarean section in the 29th week of pregnancy. Her vomiting stopped as soon as a small for gestational age but otherwise healthy male baby was delivered.

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Shah-Waardenburg syndrome: a case highlighting the importance of a holistic approach to assessing a child

We present the case of a 45-day-old child with the chief complaint of failure to pass stools for 10 days. After initial investigation, the patient was found to have Hirschsprung's disease. However, with further examination and analysis, the extremely rare diagnosis of type 4 Waardenburg syndrome was made (also known as Shah-Waardenburg syndrome or Waardenburg-Hirschsprung's disease).

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Unusual case of anxiety: trichloroethylene neurotoxicity

I present an uncommon case of recurrent, intractable anxiety that was presented acutely and slowly evolved into a chronic debilitating condition. A young previously fit and healthy 24-year-old patient presents with somewhat atypical symptoms of anxiety. Full medical work-up including examination, blood, ECG electrocardiogram, electroencephalogram and CT of the head was unremarkable. When the history was explored in detail, it was revealed he worked in the navy and was exposed to a neurotoxic solvent, trichloroethylene. This case highlights the importance of eliciting a detailed occupational history, particularly paying attention to patient demographics such as occupation and presenting symptoms that do not readily fit into diagnostic criteria.

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Short-course high-dose ibuprofen causing both early and delayed jejunal perforations in a non-smoking man

Description

A 48-year-old non-smoking man underwent laparotomy for peritonitis immediately after taking ibuprofen 800 mg 6 hourly for 14 days for back pain. His only other medication was long-term omeprazole 20 mg per day. At operation he had three separate perforations in his proximal jejunum. Fifteen centimetres of jejunum were resected with primary anastomosis. Histology showed focal mucosal ischaemic changes with normal mucosa between. There was no vasculitis. The perforations were attributed to ibuprofen intake. He made an uneventful recovery and was instructed to refrain from non-steroidal anti-inflammatory drug (NSAID) intake.

He was readmitted 5 months later with abdominal pain. He had continued omeprazole but had taken no further NSAID. CT showed extensive free intra-abdominal fluid with free gas adjacent to his proximal jejunum (figure 1), indicating a further perforation. This was confirmed at laparotomy when a 5 mm perforated ulcer was found in his proximal jejunum (figure...

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