Spinal cord occupation ratio (SCOR) and its application in the diagnosis of cervical spinal cord compression in Mucopolysaccharidoses

Abstract Introduction Mucopolysaccharidoses (MPS) can lead to cervical spinal cord compression (SCC). Diagnostic scores for SCC in MPS use the obliteration of the passage of cerebrospinal fluid in the anterior and posterior spinal cord in the sagittal section of magnetic resonance imaging (MRI). The spinal cord occupation ratio (SCOR) published, by Nouri et al (2018), establishes the spinal cord filling index for the spinal cord, identifying disproportionate spinal cord occupation in the canal. When evaluating congenital canal stenosis, the risk of spinal cord injury has been considered increased when the SCOR is ≥70% in the median sagittal plane or ≥ 80% in the axial plane. Although these values ​​have not been validated for MPS populations, they could be useful. Objective To verify the SCOR in MPS patients with diagnosis of cervical SCC comparing the SCOR with other markers proposed in the existing MPS SCC scores, such as the extent of gliosis, clinical impact and the SCC assessment as represented by the obliteration of CSF flow. Methods We reviewed imaging tests of the cervical spine from MPS patients with previously confirmed SCC, using the SCOR measure in the median sagittal plane, evaluation of the presence and extent of spinal gliosis on MRI, evaluation of the clinical impact using a clinical score and evaluation of the images for the obliteration of cerebral spinal fluid (CSF) flow. Results Thirty-one MRI of 24 different patients were included. The average SCOR was 87.1%. This was lower (81.6%) in patients without gliosis, when compared to those with focal (90.5%) and extensive (97%) gliosis. The only patient with gliosis associated with a lacunar lesion, resulting from an acute compressive injury, had a 68% SCOR, due to the atrophic spinal cord injury. As expected, SCOR was higher in patients with total or partial CSF obliteration, but one among the 3 patients without CSF flow obliteration, with a 76% SCOR, had already developed focal gliosis and mild clinical abnormalities. Patients with more extensive gliosis had higher clinical scores. Four patients had more than one imaging scan evaluated. SCOR upward trend showed an annual average increase of 3.8%. Discussion & Conclusions The use of SCOR allows the diagnosis of cervical spinal canal stenosis in an objective way. It is possible that the cut-off values used by Nouri et al in patients with congenital stenosis could be useful to diagnose cervical stenosis in MPS patients, preceding the finding of CSF flow obstruction, presence of gliosis or clinical abnormalities. Furthermore, the use of SCOR may assist in the longitudinal evaluation of disease progression. Better follow-up and timely diagnosis allows for scheduling of surgery at the best clinical moment, minimizing complications.

Mucopolysaccharidosis VII in Brazil: natural history and clinical findings.

BACKGROUND: Mucopolysaccharidosis type VII (MPS VII), also known as Sly syndrome, caused by deficiency of the lysosomal enzyme ß-glucuronidase, is an ultra-rare disorder with scarce epidemiological data and few publications about natural history and clinical spectrum. METHODS: We conducted a case series report which included retrospective data from all MPS VII patients diagnosed through the "MPS Brazil Network" who were known to be alive in 2020 in Brazil (N = 13). Clinical data were obtained from a review of the medical records and descriptive statistics and variables were summarized using counts and percentages of the total population. RESULTS: The majority of the patients were from the Northeast region of Brazil. Among the signs and symptoms that raised the clinical suspicion of MPS, coarse face was the most frequent; 58% of the patients had a history of non-immune hydrops fetalis. All the subjects presented short neck and trunk. The majority presented typical phenotypical signs of MPS disorders. They all presented neurodevelopmental delay and cognitive impairment. About half of this cohort had knees deformities. Dysostosis multiplex was identified in almost all patients and cardiomyopathy was less frequent than observed in other types of MPSs. The mean age at diagnosis was 5 years, ranging from 1 to 14 years. Almost all patients (12/13) were homozygous for the c.526C>T (p.Leu176Phe) mutation. A novel variant of the GUSB gene was found, the c.875T>C (p.Leu292Pro), in a compound heterozygous with the c.526C>T (p.Leu176Phe) variant. CONCLUSIONS: This case series is the biggest data collection of MPS VII patients alive in Latin America. The overall clinical picture of the MPS VII patients is very similar to other MPS disorders, including a spectrum of severity and delayed diagnosis.

Mucopolysaccharidosis Type I.

Mucopolysaccharidosis type I (MPS I) is caused by the deficiency of α-l-iduronidase, leading to the storage of dermatan and heparan sulfate. There is a broad phenotypical spectrum with the presence or absence of neurological impairment. The classical form is known as Hurler syndrome, the intermediate form as Hurler-Scheie, and the most attenuated form is known as Scheie syndrome. Phenotype seems to be largely influenced by genotype. Patients usually develop several somatic symptoms such as abdominal hernias, extensive dermal melanocytosis, thoracolumbar kyphosis odontoid dysplasia, arthropathy, coxa valga and genu valgum, coarse facial features, respiratory and cardiac impairment. The diagnosis is based on the quantification of α-l-iduronidase coupled with glycosaminoglycan analysis and gene sequencing. Guidelines for treatment recommend hematopoietic stem cell transplantation for young Hurler patients (usually at less than 30 months of age). Intravenous enzyme replacement is approved and is the standard of care for attenuated-Hurler-Scheie and Scheie-forms (without cognitive impairment) and for the late-diagnosed severe-Hurler-cases. Intrathecal enzyme replacement therapy is under evaluation, but it seems to be safe and effective. Other therapeutic approaches such as gene therapy, gene editing, stop codon read through, and therapy with small molecules are under development. Newborn screening is now allowing the early identification of MPS I patients, who can then be treated within their first days of life, potentially leading to a dramatic change in the disease's progression. Supportive care is very important to improve quality of life and might include several surgeries throughout the life course.

Otolaryngologists and the Early Diagnosis of Mucopolysaccharidoses: A Cross-Sectional Study.

Mucopolysaccharidoses (MPS) are a group of inborn errors of metabolism with an aggressive and usually fatal course. Therefore, early treatment is essential because the involvement of head and neck structures is almost always present in MPS. Our study aimed to retrospectively assess-via a chart review and a survey of caregivers-the history of ear, nose and throat (ENT) symptoms, the number of otolaryngology visits prior to diagnosis, and whether otolaryngologists diagnosed the disease in a cohort of MPS patients followed at an academic medical center. Twenty-three patients were evaluated. Age at diagnosis ranged from 0.2 to 33.0 years (median, 3.2 years). Prior to being diagnosed with MPS, 20/23 (87%) patients presented with at least one episode of otalgia, airway disorder, sleep disturbance, speech delay or suspected hearing loss. One patient had an adenotonsillectomy with paracentesis of tympanic membranes. Ten of the 23 patients (43%) were seen by an otolaryngologist before the diagnosis of MPS, none of which had the disease suspected during these visits. Notwithstanding limitations, our results suggest that increased awareness of MPS among otolaryngologists may allow for earlier diagnosis and better management of these patients.

Oral and craniofacial manifestations in a Hunter syndrome patient with hematopoietic stem cell transplantation: A case report.

We described herein the oral and craniofacial features of a 7-year-old boy, diagnosed in utero with mucopolysaccharidosis II (MPS II), who was treated with hematopoietic stem cell transplantation (HSCT) at 70 days of age. The main oral clinical findings were the following: macroglossia, posterior cross-bite, crowding, pointed cuspid teeth, delayed tooth eruption, retained primary teeth, and enamel hypoplasia. The image examination showed: retention eruption, posterior primary teeth with short roots, absence of some permanent teeth, and stretching of the stylohyoid processes bilaterally. This patient showed the importance of early diagnosis and HSCT therapy in attenuating the clinical and radiographic oral and craniofacial manifestations of the MPS II patient.