Epidemiology of multiple sclerosis in the Sultanate of Oman: A hospital based study

BACKGROUND

The prevalence of multiple sclerosis (MS) has been changing not only globally but also in individual countries. We aim to estimate the prevalence of MS in the Omani population over the period from 2006-2019 as well as the incidence between 2015-2018.

METHODS

This is a retrospective observational hospital-based study. All MS patients diagnosed, as per the revised McDonald criteria, over the period from June 2006 and until May 2019, had their information reviewed for age at disease onset, gender and year of diagnosis. We obtained the population of Oman from the national census data.

RESULTS

A total of 422 patients were diagnosed with MS during the study period and the population of Oman as per the 2019 census data was 2,652,199. The estimated crude prevalence was 15.9 (95% confidence interval: 14.4 - 17.5) per 100,000 and the female to male ratio was 2.17:1. The mean age at disease onset was 27.3 ± 7.7 (range: 9 - 59) years in which 83% of the patients had the first clinical manifestation at the age of 19 - 40 years, while only 9% had a disease onset at <19 years. The annual incidence increased from 1.00 case per 100,000 in 2015 to 1.38 cases per 100,000 in 2018.

CONCLUSION

The prevalence of MS in the Omani population is 15.9 per 100,000 placing Oman as a medium risk zone.

Clinico-electrographic characteristics and classification of genetic generalized epilepsy in Oman

PURPOSE

There is a lack of information on the annual incidence of genetic generalized epilepsy (GGE) in the Arab countries, especially Oman. Ascertaining the true burden of illness has crucial implications for health policies and priorities. We aim to study the clinico-electrographic characteristics, classification, and annual incidence of GGE in Oman.

METHOD

Using the cross-sectional data of EEGs obtained from all patients with GGE who presented to Sultan Qaboos University hospital (major referral center for epilepsy in Oman) from January 2007 to June 2014. Analyses were performed using univariate statistics.

RESULTS

Approximately 10,423 patients had EEG studies during the study period of which 376 patients (3.6 %) had EEG abnormalities suggestive of GGE. Forty two percent of the 376 GGE patients were male with ages ranging from 3 to 58 years. We were able to classify 273 patients to one of the GGE syndromes. Forty-three percent of 130 patients had a positive family history of epilepsy in their first or second-degree relatives. The generalized tonic-clonic seizure was the most common seizure type observed in 242 patients (64 %; 95 %CI: 59.2 %-68.9 %). Juvenile myoclonic epilepsy was the most common epilepsy syndrome (41 % of the total GGE patients) encountered in our region. A significant female predominance (9.7 % vs 2.5 %; p = 0.016) was observed in juvenile absence epilepsy. Certain interictal focal EEG abnormalities did not exclude a diagnosis of GGE. An average annual GGE incidence of 2.9 % (95 % CI: 2.6 %-3.2 %) was observed during the study period.

CONCLUSION

This hospital-based study is the first of its kind in the Arabian Gulf region, classifying the different subcategories of GGE. Our results indicate that GGE is a common epilepsy subtype in Oman. A prospective population-based epidemiological study is required to estimate the precise frequency of GGE in Oman.

Neuromyelitis optica spectrum disorders in Arabian Gulf (NMOAG); establishment and initial characterization of a patient registry

OBJECTIVE

To describe the clinical and radiological characteristics of neuromyelitis optica spectrum disorders (NMOSD) patients from the Arabian Gulf relative to anti-aquaporin 4 antibody serostatus.

METHODS

Retrospective multicentre study of hospital records of patients diagnosed with NMOSD based on 2015 International Panel on NMOSD Diagnosis (IPND) consensus criteria.

RESULTS

One hundred forty four patients were evaluated, 64.3% were anti-AQP4 antibody positive. Mean age at onset and disease duration were 31±12 and 7 ± 6 years respectively. Patients were predominantly female (4.7:1). Overall; relapsing course (80%) was more common than monophasic (20%). Optic neuritis was the most frequent presentation (48.6%), regardless of serostatus. The proportion of patients (54.3%) with visual acuity of ≤ 0.1 was higher in the seropositive group (p = 0.018). Primary presenting symptoms of transverse myelitis (TM) were observed in 29% of patients, and were the most significant correlate of hospitalization (p<0.001). Relative to anti-APQ4 serostatus, there were no significant differences in terms of age of onset, course, relapse rates or efficacy outcomes except for oligoclonal bands (OCB), which were more often present in seronegative patients (40% vs.22.5%; p = 0.054). Irrespective of serostatus, several disease modifying therapies were instituted including steroids or immunosuppressives, mostly, rituximab and azathioprine in the cohort irrespective of serostatus. The use of rituximab resulted in reduction in disease activity.

CONCLUSION

This is the first descriptive NMOSD cohort in the Arabian Gulf region. Seropositive patients were more prevalent with female predominance. Relapsing course was more common than monophasic. However, anti-AQP4 serostatus did not impact disease duration, relapse rate or therapeutic effectiveness. These findings offer new insights into natural history of NMOSD in patients of the Arabian Gulf and allow comparison with patient populations in different World regions.

Spinocerebellar ataxia with axonal neuropathy type 1 revisited

Spinocerebellar ataxia with axonal neuropathy type 1 (SCAN1; OMIM #607250), an exceedingly rare disorder having been documented in only a single family from Saudi Arabia, is the result of an unusual mutation in the tyrosyl DNA phosphodiesterase 1 gene (TDP1). We performed high-throughput sequencing (whole exome and ataxia gene panel) in two apparently unrelated Omani families segregating sensorimotor neuropathy and ataxia in an autosomal recessive fashion. Following validation by Sanger sequencing, all affected subjects (n = 4) were confirmed to carry the known SCAN1 pathogenic homozygous variant in the TDP1 gene, NM_001008744.1:c.1478A > G (p.His493Arg). In keeping with the initial description, our patients demonstrated progressive ataxia, cerebellar atrophy and disabling axonal sensori-motor neuropathy (n = 4), hypercholesterolemia (n = 2) and elevated serum alpha fetoprotein (n = 3). In addition, our patients also had mild cognitive deficits in multiple domains (n = 3), a feature not previously reported. Our findings independently revalidate the phenotype of TDP1 mutation and expand the clinical spectrum to include mild cognitive deficits. Haplotype sharing, as determined by DNA microarray (CytoScan HD), attests to a possible common founder mutation in the Arab population.

Recessive distal motor neuropathy with pyramidal signs in an Omani kindred: underlying novel mutation in the SIGMAR1 gene

BACKGROUND AND PURPOSE

Distal hereditary motor neuropathy (dHMN) due to sigma non-opioid intracellular receptor 1 (SIGMAR1) gene mutation (OMIM 601978.0003) is a rare neuromuscular disorder characterized by prominent amyotrophic distal limb weakness and co-existing pyramidal signs initially described in a Chinese family recently. We report an extended consanguineous Omani family segregating dHMN with pyramidal signs in an autosomal recessive pattern and describe a novel mutation in the SIGMAR1 gene underlying this motor phenotype. We also provide an update on the reported phenotypic profile of SIGMAR1 mutations.

METHODS

We utilized homozygosity mapping and whole-exome sequencing of leucocyte DNA obtained from three affected members of an Omani family who manifested with a length-dependent motor neuropathy and pyramidal signs.

RESULTS

We identified a novel C>T transition at nucleotide position 238 (c.238C>T) in exon 2 of the SIGMAR1 gene. Sanger sequencing and segregation analysis confirmed the presence of two copies of the variant in the affected subjects, unlike the unaffected healthy parents/sibling who carried, at most, a single copy. The T allele is predicted to cause a truncating mutation (p.Gln80*), probably flagging the mRNA for nonsense-mediated decay leading to a complete loss of function, thereby potentially contributing to the disease process.

CONCLUSIONS

Our finding expands the spectrum of SIGMAR1 mutations causing recessive dHMN and indicates that this disorder is pan-ethnic. SIGMAR1 mutation should be included in the diagnostic panel of a dHMN, especially if there are co-existing pyramidal signs and autosomal recessive inheritance.

Encephalopathy mimicking non-convulsive status Epilepticus

Primary hyperammonemic encephalopathy due to urea cycle disorders (UCD) typically manifests with episodic unresponsiveness and this clinical entity is not often included in the differential diagnosis of presumed non-convulsive status epilepticus (NCSE). However, this diagnostic consideration has therapeutic implications. In this report, we document the therapeutic importance of elucidating the specific cause of hyperammonemic encephalopathy that closely mimicked NCSE through 2 unique illustrative cases.

Prevalence of Sleep-Disordered Breathing During Routine Electroencephalogram (EEG): A Hospital-Based Descriptive Study

Sleep-disordered breathing (SDB) in adults is a common condition that is associated with a range of medical problems including hypertension, cardiovascular complications, and increase of seizure frequency in susceptible individuals. Polysomnography (PSG) is considered the gold standard measure in the diagnosis of SDB. This is an observational study on the frequency of SDB in adult patients referred for routine EEG. We found that routine EEG was capable of detecting moderate to severe symptoms of SDB in 14% of adult patients (95% confidence interval = 8.1-19.9%). The state of sleep during a routine EEG recording could help in assessing a SDB pattern and could provide an opportunity for further diagnostic sleep consultation if the patient has not previously reported problems with sleep or if SDB was not considered by the referring physician. This study underscores the need for a practice approach to ensure that patients suffering from SDB are properly referred to a sleep specialist. In the context of this report, some training and experience in PSG can be an added advantage for EEG technologists in the detection of SDB.

Predictive Value of Short-Term EEG Recording in Critically ill Adult Patients

We assessed the EEG patterns and their prognostic significance in critically ill adult patients with encephalopathy, by digital EEGs lasting lip to 1 hour Of the 110 patients (age: 43.8 ± 19.4 years, male: female:1.6:1) studied, 32% had hypoxic ischemic encephalopathy (HIE), 17% severe infections, and 14.5% stroke. Observed EEG patterns were diffuse slowing (41%), low-voltage cerebral activity (LVCA, 18%), nonconvulsive status epilepticus (NCSE, 13.6%), and periodic abnormalities (9.1%). LVCA, age, Glasgow Coma Score (GCS) < 8, HIE, and modified Hockaday's EEG grades of IV and V were associated with poor outcome (p < 0.005) at hospital discharge; generalized slowing was associated with a relatively good outcome (p = 0.003). On multivariate analysis, factors independently predictive of mortality were LVCA, older age, and poor GCS. In conclusion, LVCA and generalized background slowing were common EEG patterns among critically ill intensive care unit (ICU) patients with encephalopathy of varied etiologies. While LVCA was associated with a poor outcome, generalized background slowing predicted better prognosis. Conventional short-duration, bedside EEG studies could aid in the recognition of electrographic patterns of prognostic importance in facilities where continuous EEG monitoring is lacking.

Idiopathic intracranial hypertension presenting as postpartum headache

Postpartum headache is described as headache and neck or shoulder pain during the first 6 weeks after delivery. Common causes of headache in the puerperium are migraine headache and tension headache; other causes include pre-eclampsia/eclampsia, post-dural puncture headache, cortical vein thrombosis, subarachnoid hemorrhage, posterior reversible leukoencephalopathy syndrome, brain tumor, cerebral ischemia, meningitis, and so forth. Idiopathic intracranial hypertension (IIH) is a rare cause of postpartum headache. It is usually associated with papilledema, headache, and elevated intracranial pressure without any focal neurologic abnormality in an otherwise healthy person. It is more commonly seen in obese women of reproductive age group, but rare during pregnancy and postpartum. We present a case of IIH who presented to us 18 days after cesarean section with severe headache and was successfully managed.

Varicella zoster virus pneumonitis and brainstem encephalitis without skin rash in an immunocompetent adult

Varicella zoster virus (VZV) pneumonitis and brainstem encephalitis developed in an immunocompetent adult without rash. Chest computed tomography exhibited nodularity; lung biopsy revealed multinucleated giant cells, Cowdry A inclusions, VZV antigen, and DNA. Varicella zoster virus central nervous system disease was verified by cerebrospinal fluid (CSF) anti-VZV IgG antibody with reduced serum/CSF ratios.

The nature of progression in Parkinson's disease: an application of non-linear, multivariate, longitudinal random effects modelling

Background

To date, statistical methods that take into account fully the non-linear, longitudinal and multivariate aspects of clinical data have not been applied to the study of progression in Parkinson’s disease (PD). In this paper, we demonstrate the usefulness of such methodology for studying the temporal and spatial aspects of the progression of PD. Extending this methodology further, we also explore the presymptomatic course of this disease.

Methods

Longitudinal Positron Emission Tomography (PET) measurements were collected on 78 PD patients, from 4 subregions on each side of the brain, using 3 different radiotracers. Non-linear, multivariate, longitudinal random effects modelling was applied to analyze and interpret these data.

Results

The data showed a non-linear decline in PET measurements, which we modelled successfully by an exponential function depending on two patient-related covariates duration since symptom onset and age at symptom onset. We found that the degree of damage was significantly greater in the posterior putamen than in the anterior putamen throughout the disease. We also found that over the course of the illness, the difference between the less affected and more affected sides of the brain decreased in the anterior putamen. Younger patients had significantly poorer measurements than older patients at the time of symptom onset suggesting more effective compensatory mechanisms delaying the onset of symptoms. Cautious extrapolation showed that disease onset had occurred some 8 to 17 years prior to symptom onset.

Conclusions

Our model provides important biological insights into the pathogenesis of PD, as well as its preclinical aspects. Our methodology can be applied widely to study many other chronic progressive diseases.

Treatable Neuropsychiatric Syndrome of Catatonia: A Case Review from Oman

Catatonia is a potentially treatable neuropsychiatric syndrome less commonly encountered in developed countries these days. This review presents a case of a 19-year-old male with catatonic signs and symptoms compounded within a spectrum of a mood disorder, as well as literature review of the current treatment guidelines for this condition. There was no structural brain lesion or abnormality on cranial magnetic resonance imaging. The patient demonstrated favorable therapeutic response to benzodiazepine. This report discusses the management approach for catatonia through the case illustration, in an attempt to improve awareness and prompt recognition of this important disorder among physicians in Oman.

Acute drug overdose: clinical profile, etiologic spectrum and determinants of duration of intensive medical treatment

OBJECTIVES

Acute drug overdosing is an important cause of organ dysfunction and metabolic derangements and the patients often require intensive care. This study aims to determine the clinical pattern of severe drug overdose as well as the factors influencing the duration of intensive care

METHODS

The clinical characteristics and course of consecutive adult patients admitted with a diagnosis of acute drug poisoning in the ICU of a tertiary hospital in Oman from January 2007 to December 2008 were reviewed retrospectively from the electronic case records.

RESULTS

Acute drug poisoning (n=29) constituted 3.9% of admissions to the ICU. Mean age was 29.38±7.9 years. They were brought in by their relatives (72%) or the state services (24%). Accidental poisoning was noted in 21 patients (72%) and suicidal overdosing in 6 (21%). The commonest drug was an opioid (65.5%). Glasgow Coma Scale score of ≤8 was recorded in 18 (62.1%). Sixty two percent of patients required mechanical ventilation. The prominent complications were hypotension in 9 (31%), pulmonary in 19 (65.5%), hepatic in 18 (62.1%) and renal in 12 (41.4%) patients. The major electrolytes abnormalities were low bicarbonate in 11 (37.9%), hyponatremia in 5 (17.2%) and hypokalemia in 4 (13.8%). Patients stayed in the ICU for 1 to 20 days (median-2 days). Factors associated with a longer ICU stay included hypotension upon arrival (p=0.048) and the need for mechanical ventilation on the first (p=0.001) and second (p=0.001) days of hospitalization. There was no mortality.

CONCLUSION

Early and prompt intensive medical therapy in acute drug poisoning can favorably influence the outcome. In addition, the presence of hypotension and requirement of mechanical ventilation on the first two days of hospitalization were responsible for prolonged ICU stay.

Full Outline of UnResponsiveness score and Glasgow Coma Scale in medical patients with altered sensorium: interrater reliability and relation to outcome

PURPOSE

Full Outline of UnResponsiveness, or FOUR score (FS), is a recently described scoring system for evaluation of altered sensorium. This study examined interrater reliability for FS and Glasgow Coma Scale (GCS) among medical patients with altered mental status and compared outcome predictability of GCS, FS, and Sequential Organ Failure Assessment score.

PATIENTS AND METHODS

Adult patients with altered mental status due to medical causes were rated by neurology consultants and internal medicine residents on FS and GCS. Interobserver reliability for GCS and FS was assessed using κ score. Relation with outcomes was explored using univariate and multivariate analyses.

MAIN RESULTS

Of the 100 patients (age, 62 ± 17 years), 60 had neurologic conditions; 26, metabolic encephalopathy; 9, infections; and 7, others. Thirty-nine patients died at 3 months. κ Scores ranged from 0.71 to 0.85 for GCS and from 0.71 to 0.95 for FS. On multivariate analysis, GCS was predictive of outcome at 3 months; FS was predictive of mortality. Area under the receiver operating characteristic curves suggested equivalent performance of both scoring systems.

CONCLUSIONS

Interrater reliability and outcome predictability for FS were comparable with those for GCS. This study supports the use of FS for evaluation of altered mental status in the medical wards.

Misdiagnosis of Myasthenia Gravis and Subsequent Clinical Implication: A case report and review of literature

The autoimmune disease, myasthenia gravis (MG), can mimic a variety of neurological disorders leading to a delay in diagnosis and treatment. On occasions, misdiagnosis of MG could lead to unnecessary and potentially harmful therapeutic interventions. We report on a 12 year-old boy, in whom MG was mistaken for meningitic sequelae and subsequently for critical neuropathy/myopathy resulting in considerable morbidity for nearly a decade. Subsequent correct diagnosis and optimal management resulted in significant improvement in his functional status. We discuss the importance of considering MG as one of the potential differential diagnoses among cases of recurrent respiratory pump failure, or unexplained bulbar symptoms where documentary proof of the previous diagnoses including work-up for MG is lacking. We also review the literature on MG misdiagnosis and highlight the potential pitfalls in MG diagnosis.

Longitudinal evolution of compensatory changes in striatal dopamine processing in Parkinson's disease

Parkinson's disease is a relentlessly progressive neurodegenerative disease. Breakdown of compensatory mechanisms influencing putaminal dopamine processing could contribute to the progressive motor symptoms. We studied a cohort of 78 subjects (at baseline) with sporadic Parkinson's disease and 35 healthy controls with multi-tracer positron emission tomography scans to investigate the evolution of adaptive mechanisms influencing striatal dopamine processing in Parkinson's disease progression. Presynaptic dopaminergic integrity was assessed with three radioligands: (i) [(11)C](±)dihydrotetrabenazine, to estimate the density of vesicular monoamine transporter type 2; (ii) [(11)C]d-threo-methylphenidate, to label the dopamine transporter; and (iii) 6-[(18)F]fluoro-L-DOPA, to assess the activity of aromatic amino acid decarboxylase and storage of 6-[(18)F]-fluorodopamine in synaptic vesicles. The subjects with Parkinson's disease and the healthy controls underwent positron emission tomography scans at the initial visit and after 4 and 8 years of follow-up. Non-linear multivariate regression analyses with random effects were utilized to model the longitudinal changes in tracer values in the putamen standardized relative to normal controls. We found evidence for possible upregulation of dopamine synthesis and downregulation of dopamine transporter in the more severely affected putamen in the early stage of Parkinson's disease. The standardized 6-[(18)F]fluoro-L-DOPA and [(11)C]d-threo-methylphenidate values tended to approach [(11)C](±)dihydrotetrabenazine values in the putamen in later stages of disease (i.e. for [(11)C](±)dihydrotetrabenazine values <25% of normal), when the rates of decline in the positron emission tomography measurements were similar for all the markers. Our data suggest that compensatory mechanisms decline as Parkinson's disease progresses. This breakdown of compensatory strategies in the putamen could contribute to the progression of motor symptoms in advanced disease.

Callosal warning syndrome

OBJECTIVE

To report the clinical and imaging findings in a patient with an initial fluctuating disconnection syndrome due to corpus callosal ischemia that ultimately culminated in infarction with persistent symptoms.

CASE REPORT

A 40-year-old, hypertensive, right-handed man presented with transient, stereotyped symptoms of corpus callosal disconnection (intermanual conflict, apraxia, dysgraphia and construction difficulties in his left hand). Serial magnetic resonance imaging scans demonstrated the ischemic nature of the initial fluctuating symptoms and later showed callosal infarction when the symptoms were persistent. Magnetic resonance angiogram did not reveal significant stenosis or occlusion of the internal carotid or proximal portion of anterior cerebral arteries. Patient received standard treatment for ischemic stroke and at follow-up 1 month later, had mild left hand apraxia, dysgraphia and construction difficulties.

CONCLUSION

The case highlights the unusual occurrence of crescendo transient ischemic attacks culminating in infarction in the location of corpus callosum. We have termed this novel stroke syndrome as 'callosal warning syndrome' as the temporal profile was quite indistinguishable from that of relatively well-known stroke warning syndromes in the location of internal capsule and pontine tegmentum.

Dopamine turnover increases in asymptomatic LRRK2 mutations carriers

Increase in dopamine (DA) turnover was found to occur early in symptomatic Parkinson's disease (PD) and to be functionally related to the dopamine transporter (DAT). The objectives of this study were to examine changes in DA turnover in the asymptomatic PD phase; to compare them with changes in other dopaminergic markers, and to investigate a possible relationship between DAT and DA turnover. Eight subjects from families at increased risk of PD due to LRRK2 mutation were investigated. Positron emission tomography imaging was performed with: ¹⁸F-fluorodopa to determine the effective DA distribution volume (EDV), the inverse of DA turnover, and the DA uptake rate K(occ), a marker of DA synthesis and storage; ¹¹C-methylphenidate (MP, a DAT marker) and ¹¹C-dihydrotetrabenazine (DTBZ, a VMAT2 marker) to estimate the binding potentials BP(ND_MP) and BP(ND_DTBZ). On average, EDV showed the largest reduction from age-matched control values (42%) followed by BP(ND_MP) (23%) and BP(ND_DTBZ) (17%), whereas K(occ) remained in the normal range for all subjects. No correlation was found between EDV and any other marker. DA turnover was found to be elevated in asymptomatic mutation carriers at increased risk of PD. Such change was determined to be larger than and statistically independent from changes observed with the other markers. These results support a compensatory role of increased DA turnover in presymptomatic disease and indicate that at this stage, in contrast to the symptomatic PD phase, increased turnover is not related to DAT.

Spinal Cord Infarction following Abdominal Surgery and Postoperative Epidural Analgaesia

Ischemic infarction is a rare cause of acute myelopathy. We report the case of a young woman admitted to Sultan Qaboos University Hospital, Oman, who developed extensive spinal cord infarction in the setting of surgical evacuation and packing of liver haematoma and post-operative epidural analgesia. She had no vascular risk factors for stroke. The vascular mechanism underlying ischemic myelopathy and the relationship to abdominal surgery and epidural analgesia are discussed.

Response to heat pain stimulation in idiopathic Parkinson's disease

BACKGROUND

Pain is a prominent nonmotor symptom in Parkinson's disease (PD) but has not been well studied.

OBJECTIVE

The aim of this study is to assess thermal experience and emotional content, as well as side-to-side sensory differences in PD "off" and "on" dopaminergic therapy following thermal cutaneous stimulation.

DESIGN

Cross-sectional design.

SETTING

University teaching hospital.

METHODS

Twelve PD subjects experiencing motor fluctuations but no pain symptoms and 13 healthy controls participated in the study. Heat pain and emotional content were assessed using a thermode and visual analog scales in medication on and off states in PD and without medication in healthy controls.

RESULTS

There were no side to side differences in heat pain intensity or between PD medication on state and PD medication off state. Unexpectedly, PD subjects reported a higher degree of unpleasantness in response to heat pain while on medication compared with the off state.

CONCLUSIONS

These results suggest that the perception of heat pain is mediated, at least in part, by nondopaminergic systems in PD, while dopamine might modulate the affective component of pain.