Longitudinal dysphagia assessment in adult patients with nephropathic cystinosis using the Modified Barium Swallow Impairment Profile.

INTRODUCTION/AIMS: Nephropathic cystinosis is a lysosomal storage disorder with known myopathic features, including dysphagia. Evaluation of oropharyngeal swallowing physiology can be standardized using the Modified Barium Swallow Impairment Profile (MBSImP), a validated assessment tool used to analyze and rate swallowing across 17 distinct physiologic domains. Our objective was to better characterize swallowing impairments in nephropathic cystinosis using MBSImP analysis. METHODS: We retrospectively evaluated 40 video fluoroscopic swallowing studies performed at two time points over 1 y in patients with nephropathic cystinosis with various levels of oral and pharyngeal stage dysphagia. Patients completed two self-administered dysphagia outcome measures (the M. D. Anderson Dysphagia Inventory [MDADI] and the 10-item Eating Assessment Tool [EAT-10]). RESULTS: We demonstrated oral stage and pharyngeal stage dysphagia across domains that impacted bolus control, transit, and clearance through both the oral cavity and pharyngeal lumen. Also captured were deficits related to onset and completeness of laryngeal closure that impact airway protection during swallow. There were significant correlations between pharyngeal total score and EAT-10 (r = 0.5, p < 0.001) and between oral total score and EAT-10 (r = 0.7, p < 0.001), MDADI-e (r = -0.6, p < 0.001), MDADI-p (r = -0.5, p < 0.001) and MDADI-c (r = -0.6, p < 0.001). There were no differences in oral or pharyngeal total scores across the 1-y time span. DISCUSSION: This study identifies oral and pharyngeal stage dysphagia as crucial to patients with nephropathic cystinosis and paves the path for future studies of treatment targets.

Central Nervous System Complications in Cystinosis: The Role of Neuroimaging.

Despite improvement in the specific treatment, clinical and anatomo-functional central nervous system (CNS) abnormalities of various severities are still observed in cystinosis patients. Patients who develop CNS complications today have a worse compliance to cysteamine treatment. Radiological studies have shown that cortical or central (ventriculomegaly) atrophy is observed in more than two thirds of cystinosis patients' magnetic resonance imaging (MRI) and correlates with the intelligence quotient score. Half of cystinosis patients have marked aspecific white matter hyperintensities. The development of advanced neuroimaging techniques provides new tools to further investigate CNS complications. A recent neuroimaging study using a voxel-based morphometry approach showed that cystinosis patients present a decreased grey matter volume in the left middle frontal gyrus. Diffusion tensor imaging studies have shown white matter microstructure abnormalities in children and adults with cystinosis, respectively in areas of the dorsal visual pathway and within the corpus callosum's body. Finally, leucocyte cystine levels are associated with decreased resting cerebral blood flow, measured by arterial spin labelling, in the frontal cortex, which could be associated with the neurocognitive deficits described in these patients. These results reinforce the relevance of neuroimaging studies to further understand the mechanisms that underline CNS impairments.

Non-invasive intradermal imaging of cystine crystals in cystinosis.

IMPORTANCE: Development of noninvasive methodology to reproducibly measure tissue cystine crystal load to assess disease status and guide clinical care in cystinosis, an inherited lysosomal storage disorder characterized by widespread cystine crystal accumulation. OBJECTIVE: To develop an unbiased and semi-automated imaging methodology to quantify dermal cystine crystal accumulation in patients to correlate with disease status. DESIGN, SETTING AND PARTICIPANTS: 101 participants, 70 patients and 31 healthy controls, were enrolled at the University of California, San Diego, Cystinosis Clinics, Rady Children's Hospital, San Diego and at the annual Cystinosis Research Foundation family conference for an ongoing prospective longitudinal cohort study of cystinosis patients with potential yearly follow-up. EXPOSURES: Intradermal reflectance confocal microscopy (RCM) imaging, blood collection via standard venipuncture, medical record collection, and occasional skin punch biopsies. MAIN OUTCOMES AND MEASURES: The primary outcome was to establish an automated measure of normalized confocal crystal volume (nCCV) for each subject. Secondary analysis examined the association of nCCV with various clinical indicators to assess nCCV's possible predictive potential. RESULTS: Over 2 years, 57 patients diagnosed with cystinosis (median [range] age: 15.1 yrs [0.8, 54]; 41.4% female) were intradermally assessed by RCM to produce 84 image stacks. 27 healthy individuals (38.7 yrs [10, 85]; 53.1% female) were also imaged providing 37 control image stacks. Automated 2D crystal area quantification revealed that patients had significantly elevated crystal accumulation within the superficial dermis. 3D volumetric analysis of this region was significantly higher in patients compared to healthy controls (mean [SD]: 1934.0 µm3 [1169.1] for patients vs. 363.1 µm3 [194.3] for controls, P<0.001). Medical outcome data was collected from 43 patients with infantile cystinosis (media [range] age: 11 yrs [0.8, 54]; 51% female). nCCV was positively associated with hypothyroidism (OR = 19.68, 95% CI: [1.60, 242.46], P = 0.02) and stage of chronic kidney disease (slope estimate = 0.53, 95%CI: [0.05, 1.00], P = 0.03). CONCLUSIONS AND RELEVANCE: This study used non-invasive RCM imaging to develop an intradermal cystine crystal quantification method. Results showed that cystinosis patients had increased nCCV compared to healthy controls. Level of patient nCCV correlated with several clinical outcomes suggesting nCCV may be used as a potential new biomarker for cystinosis to monitor long-term disease control and medication compliance.

Examination of corneal deposits in nephropathic cystinosis using in vivo confocal microscopy and anterior segment optical coherence tomography: an age-dependent cross sectional study.

BACKGROUND: Presence of corneal cystine crystals is the main ocular manifestation of cystinosis, although controversial findings concerning the corneal layer with the highest density have been reported. The aim of this study was the analysis of the characteristics of crystal arrangement in different corneal layers and the assessment of corneal morphological changes with age. METHODS: A cross sectional study was carried out in three children and three adults who had nephropathic cystinosis and corneal cystine depositions. All patients underwent a comprehensive ophthalmological examination including best corrected distance visual acuity, slit-lamp examination, in vivo confocal microscopy and anterior segment optical coherence tomography. An evaluation of the depth of crystal deposits and crystal density in different corneal layers was also performed. Due to the low number of subjects no statistical comparison was performed. RESULTS: Anterior segment optical coherence tomography images revealed deposition of hyperreflective crystals from limbus to limbus in each patient. Crystals appeared as randomly oriented hyperreflective, elongated structures on in vivo confocal microscopy images in all corneal layers except the endothelium. In children the deposits occurred predominantly in the anterior stroma, while in adults, the crystals were mostly localized in the posterior corneal stroma with the depth of crystal deposition showing an increasing tendency with age (mean depth of crystal density was 353.17 ± 49.23 µm in children and it was 555.75 ± 25.27 µm in adults). Mean crystal density of the epithelium was 1.47 ± 1.17 (median: 1.5; interquartile range: 0.3-2.4). Mean crystal density of the anterior and posterior stroma of children and adults was 3.37 ± 0.34 (median: 3.4; interquartile range: 3.25-3.55) vs. 1.23 ± 0.23 (median: 1.2; interquartile range: 1.05-1.35) and 0.76 ± 0.49 (median: 0.7; interquartile range: 0.4-1.15) vs. 3.63 ± 0.29 (median: 3.7; interquartile range: 3.45-3.8), respectively. Endothelium had intact structure in all cases. Some hexagonal crystals were observed in two subjects. CONCLUSIONS: In vivo confocal microscopy and anterior segment optical coherence tomography confirmed an age-related pattern of crystal deposition. In children, crystals tend to locate anteriorly, while in adults, deposits are found posteriorly in corneal stroma.

Significance of twinkling artifact on ultrasound in the diagnosis of cystine urolithiasis.

Twinkling artifact (TA) refers to the finding characterized by both a high-echoic mass upon B-mode ultrasound (US) and turbulence-like signals over the entire mass without significant blood flow on color Doppler US. TA is a characteristic sign of urolithiasis, and there has been no previous report on this finding in the digestive tract. The authors recently encountered a 2-year 9-month-old boy with cystinuria presenting with an opacified abdominal mass. Although he was originally diagnosed as having calcified stool mass, the finding of TA upon US led to the correct diagnosis of huge urolith (4.2 cm in diameter) in the urinary bladder. Laparotomic stone removal was successfully conducted and the calculus was confirmed to be composed of cystine. The finding of TA upon US facilitates identification of the structure and location of the intra-abdominal mass.

Osteopenia and fractures in cystinotic children post renal transplantation.

Many of the end-organ effects of cystinosis are known to be risk factors for osteopenia; these include deposition of cystine crystals in bone, hypothyroidism, diabetes mellitus, primary hypogonadism, urinary phosphate wasting, and chronic renal failure. While transplantation may correct the latter, it exposes the child to other risk factors for diminished bone mass, notably the use of high-dose glucocorticoids. Our objective was to determine if these multiple risk factors translate into an increased occurrence of osteopenia, as measured by dual-energy X-ray absorptiometry (DEXA), and/or fractures in this population. We examined the charts, X-rays, and bone mineral density (BMD) of all cystinotic patients post renal transplant for whom this information was available. Lumbar spine BMD was measured by DEXA scan (Hologic 4500). Z-scores were corrected for growth parameters using previously published reference data. Fracture history and pertinent serum markers of bone metabolism were also analyzed. Of the 63 renal transplants performed at our institution, 11 children were transplanted due to cystinosis. Nine of these patients, 5 male and 4 female, had had BMD evaluations, with an average age of 14.3 years (range 5-17 years) at the time of initial BMD post transplant. The mean interval between transplant and BMD evaluation was 39 months (range 3-90 months). Surprisingly, 7 of 9 patients had normal uncorrected BMD values (z-scores -1.92 to +0.02) and 7 of 9 patients had normal corrected values (z-scores -1.20 to +1.93). Three patients suffered from a total of eight fractures. Of the 3 fracture patients, 2 had normal BMD. All patients maintained good graft function and had normal calcium/phosphate mineral status. Of note, 3 of 5 male patients had evidence of primary testicular failure at earlier ages than often described, and this may be an unrecognized risk factor for bone disease in this population. Despite the numerous risk factors for developing osteopenia, these results suggest that the majority of cystinotic patients post renal transplant do not experience reduced bone mineral content as measured by DEXA. However, the significant fracture history among these patients demonstrates that DEXA cannot be used to assess fracture risk in patients with nephropathic cystinosis.

Intralysosomal cystine accumulation in mice lacking cystinosin, the protein defective in cystinosis.

Cystinosis is an autosomal recessive disorder characterized by an accumulation of intralysosomal cystine. The causative gene, CTNS, encodes cystinosin, a seven-transmembrane-domain protein, which we recently showed to be a lysosomal cystine transporter. The most severe and frequent form of cystinosis, the infantile form, appears around 6 to 12 months, with a proximal tubulopathy (de Toni-Debré-Fanconi syndrome) and ocular damage. End-stage renal failure is reached by 10 years of age. Accumulation of cystine in all tissues eventually leads to multisystemic disease. Treatment with cysteamine, which reduces the concentration of intracellular cystine, delays disease progression but has undesirable side effects. We report the first Ctns knockout mouse model generated using a promoter trap approach. We replaced the last four Ctns exons by an internal ribosome entry site-betagal-neo cassette and showed that the truncated protein was mislocalized and nonfunctional. Ctns(-/-) mice accumulated cystine in all organs tested, and cystine crystals, pathognomonic of cystinosis, were observed. Ctns(-/-) mice developed ocular changes similar to those observed in affected individuals, bone defects and behavioral anomalies. Interestingly, Ctns(-/-) mice did not develop signs of a proximal tubulopathy, or renal failure. A preliminary therapeutic trial using an oral administration of cysteamine was carried out and demonstrated the efficiency of this treatment for cystine clearance in Ctns(-/-) mice. This animal model will prove an invaluable and unique tool for testing emerging therapeutics for cystinosis.

Ultrasound biomicroscopy of the eye in cystinosis.

OBJECTIVE: To describe the ocular ultrasound biomicroscopy (UBM) findings in patients with cystinosis. METHODS: Six patients with infantile nephropathic cystinosis, aged 16 to 25 years, and 6 controls (matched for age and spherical refractive error) were examined clinically and with UBM. Scleral reflectivity, corneal and iris thickness, central anterior chamber depth, angle width, trabecular meshwork to ciliary process distance, and ciliary sulcus width were measured. RESULTS: No patient had glaucoma or posterior synechiae, but all had crystals in the trabecular meshwork apparent with gonioscopy. Using UBM, the cornea and iris appeared similar in both groups, but the scleral reflectivity was increased in patients (P =.003). The angle was narrower in patients (mean +/- SD, 20 degrees +/- 7 degrees ) than controls (31 degrees +/- 5 degrees, P<. 001). The anterior chamber was shallower in patients (2556 +/- 197 microm) than controls (2968 +/- 284 microm, P<.001). The ciliary sulcus was closed or narrow in all patients (83 +/- 112 microm) compared with controls (339 +/- 135 microm, P<.001), with a reduction in the trabecular meshwork to ciliary process distance. CONCLUSIONS: This report of ocular UBM findings in cystinosis demonstrated narrowing of the angle and a ciliary body configuration similar to that reported for plateau iris syndrome. Gonioscopy demonstrated crystals in the trabecular meshwork. These findings may explain the predisposition of these patients to glaucoma.

Dimercaptosuccinic acid distribution in renal tubular acidosis.

A 99Tcm dimercaptosuccinic acid (DMSA) scan performed after a urinary tract infection demonstrated an unusual pattern of isotope uptake, promoting further investigations leading to a diagnosis of renal tubular acidosis secondary to nephropathic cystinosis. This is known to affect isotope imaging but a unique feature in this undiagnosed case was the uncorrected metabolic acidosis, which had further altered the distribution of the DMSA. It is noteworthy because other patients referred for imaging with renal disease may also have abnormalities of acid base balance.

Hypercalciuria and ultrasound abnormalities in children with cystinosis.

We noted microscopic haematuria in children with cystinosis. To investigate this we studied urinary calcium excretion and undertook renal ultrasound scans. Most patients had elevated urinary calcium excretion and all had abnormal appearances on ultrasound scan, ranging from increased cortical echogenicity only to those with increased cortical and medullary echogenicity. The ultrasound scan appearance was graded and correlated with laboratory parameters. It remains unclear as to the aetiology of the ultrasound findings and whether they are a consequence of treatment or a hitherto unrecognised feature of the disease.

[Infantile cystinosis. A new Tunisian case]. / Cystinose infantile. Une nouvelle observation tunisienne.

A case of cystinosis in a three and a half-year-old is reported. Suggestive manifestations included severe rickets, small stature, and complex renal tubule dysfunction meeting the criteria for secondary Fanconi syndrome. Diagnosis was established by the discovery of retinal lesions upon ophtalmologic evaluation and, above all, by the finding that intracellular leukocyte cystine levels were increased to 16 mumol of 1/2 cystine per gram protein. Cystinosis is severe because it inevitably leads to renal failure. Much hope is currently placed in the use of cysteamine to delay this and other complications. At present, early antenatal diagnosis during the first ten weeks of pregnancy is needed in high-risk families to allow elective termination of pregnancy within the legal time limit.

Cerebral atrophy and nephropathic cystinosis.

The management of end stage renal failure in cystinotic children is correlated with a longer survival, sometimes complicated with neurological abnormalities. Cranial computed tomography was performed in 10 patients and showed a significant atrophy; the pathogenesis of this damage remains unclear.

Abnormalities of the liver and other organs.

The liver may undergo pathologic changes as a result of an overall disease process that also affects other organs. This article focuses on those diseases in which abnormalities of the liver are only one part of the process, and in which radiographic investigation of the liver is diagnostically important.

Evidence for cerebral involvement in nephropathic cystinosis.

Cranial computerized tomography (CCT) of 3 children with nephropathic cystinosis and chronic renal failure (CRF) revealed a hydrocephalus internus and externus. In two boys the findings consisted of bilateral dilatation of the ventricular system and of the subarachnoid space; in one boy the alterations were mainly unilateral. The children had repeated convolsions which could not be explained by deterioration of renal function. Their neurological condition was otherwise normal. In six non-cystinotic patients with chronic renal failure, CCT showed normal anatomical structures. The possibility is discussed that the hitherto unknown pathogenetic mechanism of cystinosis leads to diffuse cerebral atrophy, resulting in internal and external hydrocephalus.

Course and prognosis of bone cystinosis in adolescent and or adults.

The authors refer to their observations on a case reported five years ago. On the basis of electron microscopy findings it was classified as benign bone cystinosis of the adolescent or of the adult. His subsequent clinical recovery, and the present radiographic findings, which show spontaneous and almost complete repair, confirm the validity of the diagnosis and the importance of electron microscopy in the etiology of this rare bone lesion.

Cystinosis with crystal-induced synovitis and arthropathy.

A clinically and experimentally verified intermediary form of cystinosis is described. A 30-year old patient has been examined initially for eye complications confined to the frontal segment of the eye on the cornea and conjunctiva. The joint disease received no attention despite the fact that the motor apparatus of the patient was involved from her childhood. As regards the arthrology, the disease can be classed among crystal-induced synovitis and arthropathy. The lesion of the tubular apparatus of the kidney, which cannot transform vitamin D into its active form, represents an important factor in the genesis of osteoporosis. A description of the intermediary from of cystinosis with eye, kidney and joint symptoms was not found in the literature.

Cystinosis of bone.

The authors describe a case of cystinosis of bone that presented initial difficulties in diagnosis. They discuss the clinical features and the radiographic appearances, which demonstrated numerous zones of osteoporosis with a markedly monomelic distribution in the left leg. The condition arose as a result of trauma. Numerous accumulations of intracellular cystine crystals were revealed by the ultramicroscopic study of bone fragments obtained by biopsy, and this led the authors to diagnose the case as cystine thesaurismosis of bone. The case is of interest not only because of its exceptional rarity (it is, perhaps, the first reported case of cystinosis localized exclusively in bone), but also because it was only possible to arrive at a diagnosis by means of ultramicroscopic investigation.