Multilevel myelopathy associated with pseudohypoparathyroidism simulating diffuse skeletal hyperostosis: a case report and literature review

Genetics of Diffuse Idiopathic Skeletal Hyperostosis and Ossification of the Spinal Ligaments

PURPOSE OF REVIEW

The study aims to provide updated information on the genetic factors associated with the diagnoses 'Diffuse Idiopathic Skeletal Hyperostosis' (DISH), 'Ossification of the Posterior Longitudinal Ligament' (OPLL), and in patients with spinal ligament ossification.

RECENT FINDINGS

Recent studies have advanced our knowledge of genetic factors associated with DISH, OPLL, and other spinal ossification (ossification of the anterior longitudinal ligament [OALL] and the yellow ligament [OYL]). Several case studies of individuals afflicted with monogenic disorders, such as X-linked hypophosphatemia (XLH), demonstrate the strong association of fibroblast growth factor 23-related hypophosphatemia with OPLL, suggesting that pathogenic variants in PHEX, ENPP1, and DMP1 are associated with FGF23-phosphate wasting phenotype and strong genetic factors placing patients at risk for OPLL. Moreover, emerging evidence demonstrates that heterozygous and compound heterozygous ENPP1 pathogenic variants inducing 'Autosomal Recessive Hypophosphatemic Rickets Type 2' (ARHR2) also place patients at risk for DISH and OPLL, possibly due to the loss of inhibitory plasma pyrophosphate (PPi) which suppresses ectopic calcification and enthesis mineralization. Our findings emphasize the importance of genetic and plasma biomarker screening in the clinical evaluation of DISH and OPLL patients, with plasma PPi constituting an important new biomarker for the identification of DISH and OPLL patients whose disease course may be responsive to ENPP1 enzyme therapy, now in clinical trials for rare calcification disorders.

Pseudohypoparathyroidism mimicking cervical diffuse idiopathic skeletal hyperostosis with dysphagia: A case report and literature review

Dysphagia due to extensive ossification at anterior segments of the cervical spine is a rare occurrence and is usually attributable to diffuse idiopathic skeletal hyperostosis (DISH). We present the case of a 74-year-old female with dysphagia most likely due to ossification in pseudohypoparathyroidism type 1a (PHP1a). PHP1a is a rare, autosomal dominant disorder caused by mutations in the GNAS1 gene. Our patient had characteristic phenotype features of PHP1a, also known as Albright's hereditary osteodystrophy (AHO), which was diagnosed without genetic confirmation. She was conservatively treated with dietary measures and observation, and reported persisting symptoms of dysphagia at six-month follow-up. This is the first case to describe dysphagia in PHP1a with a similar presentation to DISH.

Prevalence and characteristics of thoracic diffuse idiopathic skeletal hyperostosis in 3299 black patients

The purpose of this study was to examine the prevalence and characteristics of thoracic diffuse idiopathic skeletal hyperostosis (T-DISH) in the Black patients using the computed tomography (CT) analysis. This study is a cross-sectional study. All patients who underwent chest CT for the trauma screening and whose race was categorized as “Black” on the questionnaire were recruited in the study from Mar 2019 to Mar 2020. Demographic data, including age, sex, body mass index (BMI), and presence of diabetes mellitus (DM), were recorded. A total of 3299 Black patients (1507 women and 1792 men) were included for the analysis. The prevalence of T-DISH was 7.7% (255 patients), with 8.6% for females and 7.0% for males. The highest prevalence was observed in patients at the age of 70 years (11.7%), followed by the age of 80 years (10.5%). The highest prevalence level of T-DISH segment was at T8, followed by T9, and T7. The most frequent number of contiguous vertebrae was seven (21%). BMI was not associated with T-DISH. The presence of DM was significantly higher in male patients with T-DISH than those without T-DISH (P = 0.02).

Symptomatic spinal cord compression: an uncommon symptom in pseudohypoparathyroidism

We describe symptomatic spinal cord compression associated with pseudohypoparathyroidism (PHP) in a young female patient and reviewed similar cases previously reported in the literature. The characteristics of these cases were analyzed from etiology, clinical subtypes, symptoms, treatment, and prognosis. Neurological examination revealed functional upper extremities with bilateral lower extremity paraplegia. Laboratory tests showed hypocalcemia, hyperphosphatemia, and elevated parathyroid hormone; high-throughput sequencing showed a heterozygous GNAS mutation in exon 12, specifically c.1006C > T (p.R336W). Imaging findings showed multilevel spinal stenosis with significant spinal cord compression at the T2-T3 level. Seventeen cases with similar characteristics were reviewed. We found that the primary clinical manifestation of these patients was bilateral lower extremity spastic paraplegia. Multilevel spinal cord compression was commonly observed, especially at the lower cervical and upper thoracic spinal cord. Most of the patients had poor surgical treatment outcome and prognosis. Clinicians should be aware of paraplegia due to spinal cord compression as a rare neurological complication in patients with PHP. Early diagnosis and treatment of PHP is one basis for preventing severe spinal cord-related complications.

Diagnosis and management of pseudohypoparathyroidism and related disorders: first international Consensus Statement

This Consensus Statement covers recommendations for the diagnosis and management of patients with pseudohypoparathyroidism (PHP) and related disorders, which comprise metabolic disorders characterized by physical findings that variably include short bones, short stature, a stocky build, early-onset obesity and ectopic ossifications, as well as endocrine defects that often include resistance to parathyroid hormone (PTH) and TSH. The presentation and severity of PHP and its related disorders vary between affected individuals with considerable clinical and molecular overlap between the different types. A specific diagnosis is often delayed owing to lack of recognition of the syndrome and associated features. The participants in this Consensus Statement agreed that the diagnosis of PHP should be based on major criteria, including resistance to PTH, ectopic ossifications, brachydactyly and early-onset obesity. The clinical and laboratory diagnosis should be confirmed by a molecular genetic analysis. Patients should be screened at diagnosis and during follow-up for specific features, such as PTH resistance, TSH resistance, growth hormone deficiency, hypogonadism, skeletal deformities, oral health, weight gain, glucose intolerance or type 2 diabetes mellitus, and hypertension, as well as subcutaneous and/or deeper ectopic ossifications and neurocognitive impairment. Overall, a coordinated and multidisciplinary approach from infancy through adulthood, including a transition programme, should help us to improve the care of patients affected by these disorders.

Nonclassic features of pseudohypoparathyroidism type 1A

PURPOSE OF REVIEW

To provide readers with a review of contemporary literature describing the evolving understanding of the pseudohypoparathyroidism type 1A (PHP1A) phenotype.

RECENT FINDINGS

The classic features of PHP1A include multihormone resistance and the Albright Hereditary Osteodystrophy phenotype (round facies, short stature, subcutaneous ossifications, brachydactyly, and early-onset obesity. Obesity may be because of a decrease in resting energy expenditure because most patients do not report significant hyperphagia. Patients with PHP1A have an increased risk of type 2 diabetes. In addition to brachydactyly and short stature, orthopedic complications can include spinal stenosis and carpal tunnel syndrome. Hearing loss, both sensorineural and conductive, has been reported in PHP1A. In addition, ear-nose-throat findings include decreased olfaction and frequent otitis media requiring tympanostomy tubes. Sleep apnea was shown to be 4.4-fold more common in children with PHP1A compared with other obese children; furthermore, asthma-like symptoms have been reported. These new findings are likely multifactorial and further research is needed to better understand these nonclassic features of PHP1A.

SUMMARY

Along with the Albright Hereditary Osteodystrophy phenotype and hormone resistance, patients with PHP1A may have additional skeletal, metabolic, ear-nose-throat, and pulmonary complications. Understanding these nonclassic features will help improve clinical care of patients with PHP1A.

Spinal cord compression in pseudohypoparathyroidism

BACKGROUND CONTEXT

Spinal cord compression associated with pseudohypoparathyroidism (PHP) is an increasingly reported sequelae of the underlying metabolic syndrome. The association of neurologic dysfunction with PHP is not well appreciated. We believe this to be secondary to a combination of underlying congenital stenosis, manifest by short pedicles secondary to premature physeal closure, and hypertrophic ossification of the vertebral bony and ligamentous complexes.

PURPOSE

The purpose of this case report is to review the case of spinal stenosis in a child with PHP Type Ia. We are aware of only eight published reports of patients with PHP Type Ia and spinal stenosis-there are only two previously known cases of pediatric spinal stenosis secondary to PHP.

STUDY DESIGN/SETTING

This is a case report detailing the symptoms, diagnosis, interventions, complications, and ultimate outcomes of a pediatric patient undergoing spinal decompression and fusion for symptomatic stenosis secondary to PHP Type Ia. Literature search was reviewed regarding the reports of spinal stenosis and PHP, and the results are culminated and discussed.

PATIENT SAMPLE

We report on a 14-year-old obese male with PHP and progressive lower extremity weakness secondary to congenital spinal stenosis. Examination revealed functional upper extremities with spastic paraplegia of bilateral lower extremities. The patient's neurologic function was cautiously monitored, but he deteriorated to a bed-bound state, preoperatively.

METHODS

The patient's chart was reviewed, summarized, and presented. Literature was searched using cross-reference of PHP and the terms "spinal stenosis," "myelopathy", "myelopathic," and "spinal cord compression." All relevant case reports were reviewed, and the results are discussed herein.

RESULTS

The patient underwent decompression and instrumented fusion of T2-T11. He improved significantly with regard to lower extremity function, achieving unassisted ambulation function after extensive rehabilitation. Results from surgical decompression in previously reported cases are mixed, ranging from full recovery to iatrogenic paraplegia.

CONCLUSIONS

The association of neurologic dysfunction with PHP is not well appreciated. It is important to highlight this rare association. Surgical decompression in patients with PHP yields mixed results but may be of greatest efficacy in younger patients who receive early intervention.

Diffuse idiopathic skeletal hyperostosis (Forestier-Rotes-Querol disease): what's new?

Diffuse idiopathic skeletal hyperostosis (DISH), also known as Forestier-Rotes-Querol disease, is characterized by the ossification of the entheses (i.e., enthesopathy). The diagnosis of DISH requires at least two (according to Forestier) or three (according to Resnick) contiguous intervertebral bridges, without severe disk alterations (in contrast to degenerative spinal disease) or ankylosis of the sacroiliac or facet joints (in contrast to spondylarthritis). Although prevalence estimates vary with the number of bridges used to define the disease, the prevalence of DISH is consistently high and increases with age and obesity. Peripheral involvement is common but difficult to ascribe to DISH in the absence of typical spinal changes. Cervical spine ossification is the most extensively studied manifestation, as dysphagia due to esophageal compression may require surgery. As with spondylarthritis, vertebral fractures on a hyperostotic fused spine may escape recognition, placing the patient at risk for complications in the event of subsequent displacement. These fractures are particularly severe, as they often involve the cervical spine and can therefore, cause major neurological impairments. DISH is associated with an increased risk of metabolic syndrome (odds ratio, 3.88). Research into the pathophysiology of DISH has established that serum levels of the natural osteogenesis inhibitor Dickkopf-1 (DKK-1) are low in patients with DISH or spondylarthritis. Although this abnormality might contribute to the entheseal ossification, it has not been found consistently.