Association between craniovertebral junction abnormalities and syringomyelia in patients with chiari malformation type-1

Objectives:To assess the correlation between craniovertebral junction (CVJ) abnormalities and syringomyelia in patients with Chiari malformation type-1 (CM1).Methods:This was a retrospective study including patients with CM1. Identification of cases was done by searching a radiology database at a university hospital from 2012 to 2017. Patients were divided into 2 groups based on whether CVJ abnormalities were present (CVJ+) or absent (CVJ-). The patients’ demographic and clinical data were reviewed. All magnetic resonance imaging studies were examined by a certified neuroradiologist.Results:Sixty-four consecutive patients with CM1 were included. The mean age was 24±17 years; 59% were females. The CVJ+ group had more female patients (p = 0.012). The most frequent CVJ abnormality was platybasia (71%), followed by short clivus (44%) and cervical kyphosis (33%). The CVJ abnormalities were more in Syringomyelia cases (p = 0.045). However, the results were not significant when hydrocephalus cases were excluded.Conclusion:Among CM1 patients, CVJ abnormalities were found more in patients with syringomyelia. Future studies with larger sample size are required to further study the correlation between CVJ abnormalities and both syringomyelia and hydrocephalus in CM1 patients.

Chiari malformation type-1 (CM1) was first described in 1891 by Austrian pathologist Hans Chiari.1,2 The CM1 is defined as caudal displacement of the cerebellar tonsils below the foramen magnum by 5 mm or more.3,4 This definition is merely a radiological definition. In the literature, the degree of cerebellar tonsil displacement varies from 3 mm to 5 mm.4 CM1 affects approximately 1% of the population and may involve a spectrum of neurologic involvement.2 Syringomyelia is reported in 25% of CM1 cases and may cause irreversible damage to the spinal cord with subsequent neurological deficits.5The pathophysiology of syringomyelia development in patients with CM1 has been extensively studied.6-9 Majority of publications indicated a block to the cerebrospinal fluid (CSF) circulation at the level of the craniovertebral junction (CVJ).8,9 Subsequently, the cerebrospinal fluid (CSF) accumulates and forms syringomyelia.8,9 The source of the CSF forming the syringomyelia can be from the fourth ventricle, the subarachnoid space (SAS), or from an extracellular source.8,9 From the 1950s to the 1970s, syringomyelia was believed to result from a difference in CSF pressure between the fourth ventricle and the central canal of the spinal canal.7 Theories to explain this mechanism include James Gardner’s water-hammer theory, Bernard Williams’ cranio-spinal pressure dissociation theory, and Ball and Dayan’s theory of tonsillar obstruction to the CSF pathway.10-12 In the 1990s, Oldfield believed that the mechanism of the development of syringomyelia involved abnormal CSF flow at the level of the foramen magnum.6,7 The descent of the cerebellar tonsils with each cardiac cycle produces a pressure wave in the spinal SAS, and thereby compresses the spinal cord from the outside and propagates a syrinx.7,9Several intradural and extradural factors have been implicated in the pathophysiology of CM1. Among the intradural factors identified during surgery for CM1, the presence of an arachnoid membrane obstructing the foramen of Magendie (i.e., an arachnoid veil) was significantly more frequent in patients with an associated syringomyelia.6 Other studies have examined whether the degree of tonsillar descent below foramen magnum in the CM1 patients is a contributing factor to the development of syringomyelia; however, the impact of tonsillar descent is controversial.6,9,13 Some studies have reported that the rate of syringomyelia increases as the degree of tonsillar herniation increases.6,9 As a possible explanation for syringomyelia development, other studies14,15 have addressed crowding of the SAS at the foramen magnum caused by tonsillar decent. In a study by Doruk et al15, the measured cervicomedullary compression ratio, defined as the ratio of the area occupied by the cerebellar tonsils to the area of the foramen magnum, was significantly correlated with the development of syringomyelia. This ratio could reflect the severity of blockage of the SAS at the CVJ and further supports the previously described mechanisms of syringomyelia development.9Extradural abnormalities at the CVJ are associated with CM1.15 Such pathologies include a small posterior cranial fossa, platybasia, basilar invagination, and short clivus.3,6,8,9 Several studies have examined the presence of CVJ abnormities in CM1 patients with and without syringomyelia.13,16-21 However, the presence of associated syringomyelia within the context of CM1 with and without CVJ abnormalities was inadequately highlighted. For instance, in one study,13 syringomyelia existed in 64% of CM1 patients with a short clivus, compared to 36% of CM1 patients without a short clivus. In order to further understand the relationship between the presence of one or more CVJ abnormalities and syringomyelia in CM1, the current study was conducted. Such knowledge will likely enhance the understanding of CVJ relationship with CM1 and may aid in the management of syringomyelia in such patients.     

Imaging Approach to the Diagnosis of Acute Appendicitis in a Group of Teaching Hospitals With 24/7 In-house Availability of Ultrasound Technologist: Effect of Timing of Request on Imaging Modality

Purpose

The study sought determine effect of requisition timing on the initial-choice imaging modality in appendicitis evaluation.

Herpes zoster in eastern Saudi Arabia: clinical presentation and management

BACKGROUND: Herpes zoster (HZ), caused by varicella zoster virus (VZV), initially produces chicken-pox, then the virus lies dormant in the dorsal root ganglia. The virus can reactivate after many years and results in HZ along ganglion's distribution. Old age, trauma, stress, diabetes mellitus, and immune suppression are important risk factors for the reactivation. Herpes zoster is characterized by unilateral radicular pain and vesicular eruption that is generally limited to the dermatome innervated by the affected ganglion. In immunocompromised individuals, disseminated zoster may develop. The aims of therapy in HZ are to control pain or reduce its severity by the use of analgesics, reduce the duration and eruption of new lesions, and prevent complications, particularly postherpetic neuralgia (PHN) by appropriate antiviral therapy. METHODS: All cases of HZ seen in the dermatology clinic at King Fahd Hospital of the University (KFHU) from 1988 to 2006 were included in the study. Their diagnoses were based on the clinical presentation. The following parameters were collected and analyzed: age, sex, nationality, symptoms, dermatomal distribution, complications, coexisting diseases, and disease management. RESULTS: Of 22 749 new cases seen in the dermatology clinic over 18 years, 141 were HZ, with an occurrence of 0.62%. Male to female ratio was 2:1 and the age ranged from 14 months to 80 years. The thoracic dermatomes were the most commonly involved. The most frequent coexisting disease was diabetes mellitus, and the most common complication of HZ was PHN. Most patients with HZ ophthalmicus developed eye complications. CONCLUSION: The occurrence of HZ is 0.62% in patients reporting to the dermatology clinic of the hospital. Males are little more affected than females. The thoracic dermatomes are the most frequently involved. Diabetes mellitus is the most frequent coexisting disease. Postherpetic neuralgia is the most common complication of HZ.     

The mid-mesial canal prevalence in mandibular molars of a Saudi population: A cone-beam computed tomography study

IntroductionThe aim was to assess the prevalence of Mid Mesial Canal (MMC) in the first and second mandibular molars in a Saudi subpopulation sample and assess its relation to side, gender, and age using Cone beam computed tomography (CBCT).MethodsThe CBCT scans at King Saud University Dental Hospital between 2016 and 2019 were reviewed and filtered. The MMC of the mandibular molars were assessed according to Pomeranz et al. classification which was: (1) independent; (2) fin; (3) confluent with the mesiobuccal canal; and (4) confluent with the mesiolingual canal. Three calibrated observers examined the MMC on all planes at both sides. Age and gender factors were used to analyze that prevalence. A chi-squared test was used and (P ≤ 0.05) was considered to be statistically significant.Results395 patients, and 1377 teeth met the inclusion criteria. The total number of mid-mesial canals was 12 (0.9%): nine at the mandibular first molar (1.3%) and three in the mandibular second molar (0.4%). The most common type of mid-mesial canal was confluent (n = 10), of which 6 fused with the mesiobuccal canal and 4 fused with the mesiolingual canal. Two canals were of the fin type, and there was no instance of independent mid-mesial canal. There was no significant difference between all variables: tooth type, tooth side, patient gender, and patient age group (p > 0.05).ConclusionIn this study, the most common MMC configuration was the confluent type followed by the fin type and no independent type were found. The patient side, gender and age did not influence the prevalence of the MMC.     

A review of mechanism of action of outdoor exposure in preventing myopia incidence and progression

Various studies have suggested several environmental, pharmacological, medical, and optical interventions and some are in use but their efficacy in myopia control may be transient, and the cellular, molecular, and biochemical mechanisms involved unclear. Daylight exposure is currently regarded as an effective and enduring strategy in the control of myopia development and progression. However, the mechanism behind the effect of outdoor exposure and its association with genetic predisposition and other relatively more significant environmental factors on myopia is still a conundrum. This review focuses on survey-based and intervention-based studies carried out to propose a mechanism that accounts for myopia development and important for its control.