Total craniospinal decompression in achondroplastic stenosis

Small posterior fossa in Chiari I malformation affected families is significantly linked to 1q43-44 and 12q23-24.11 using whole exome sequencing

The posterior fossa of the cranium contains the cerebellum and brainstem. Processes that reduce the volume of the posterior fossa squeeze the cerebellum and brainstem caudally, resulting in Chiari I malformation (CM1). CM1 causes neck pain, balance issues, decreased motor skills and headaches in those affected. We have posterior fossa measurements and whole exome sequence data on individuals from 7 extended families from Russia that have a family history of CM1. We performed parametric linkage analyses using an autosomal dominant inheritance model with a disease allele frequency of 0.01 and a penetrance of 0.8 for carriers and 0.0 for non-carriers. Variant-based two-point linkage analysis and gene-based linkage analysis was performed. Our results found a genome-wide significant signal on chromosome 1q43-44 (max HLOD = 3.3) in the variant-based analysis and 12q23 (max HLOD = 4.2) in the gene-based analysis. In both cases, the signal was driven by a single (different) family that contained a long, linked haplotype across the region in question. Using functional annotation, we were able to identify several rare nonsynonymous variants that were enriched in each family. The best candidate genes were rs765865412:G>A in MYBPC1 for the 12q haplotype and rs61749963:A>G in COX20 for the 1q haplotype. Good candidate variants in the 1q haplotype were also identified in CEP170 and AKT. Further laboratory work is planned to verify the causality of these genes.

Progression of low back and lower extremity pain in a cohort of patients with achondroplasia

OBJECT

The aim of this study was to assess the natural history of pain associated with spinal stenosis in individuals with achondroplasia and to characterize pain patterns and associated functional and psychological effects.

METHODS

The authors measured pain severity, spatial distribution of pain, functional disability, psychological distress, physical symptoms other than pain, and healthcare utilization in 181 individuals with achondroplasia. They also assessed low back and/or lower extremity pain at the initial visit and 1-year follow-up via self-rated patient questionnaires, calculated composite scores from responses via component analyses, and used repeated measures linear regression analyses for score changes (significance, p < or = 0.05).

RESULTS

At the follow-up, back pain severity was unchanged. Patients reported significant progression of pain toward involvement of the lower extremities and significant increases in lower extremity pain severity overall. There were also significant increases in healthcare utilization overall. Compared with patients with back pain only, those with back pain and proximal or distal leg pain had higher self-rated pain severity; higher functional disability; and more bowel and bladder dysfunction symptoms, sleep disturbances, extremity numbness, and psychological distress.

CONCLUSIONS

Individuals with achondroplasia and symptomatic spinal stenosis often experience back pain, which may progress to lower extremity pain and debilitating consequences. A more thorough understanding of the progression of spatial pain characteristics and pain severity may aid clinical decision making regarding the optimal timing for intervention.

Postlaminectomy kyphosis in the skeletally immature achondroplast

STUDY DESIGN

Retrospective review.

OBJECTIVES

To determine the risk of postlaminectomy thoracolumbar kyphosis in skeletally immature achondroplasts and evaluate the need for concurrent fusion at multilevel decompression.

SUMMARY OF BACKGROUND DATA

Spinal stenosis is a relatively common complication of achondroplasia. Although most achondroplasts do not develop symptomatic spinal stenosis until the third or fourth decades, some patients become symptomatic before skeletal maturity. While postlaminectomy kyphosis typically does not occur in the adult achondroplast, it is not known if it occurs in the skeletally immature achondroplast.

METHODS

The charts and radiographs of 10 consecutive skeletally immature achondroplasts that underwent surgical treatment for symptomatic spinal stenosis during a 10-year period were retrospectively reviewed. The average age of the 6 male and 4 female patients at surgery was 9.2 years (range 6-16). All patients had preoperative lateral radiographs. Decompression consisted of multilevel (5-8) thoracolumbar laminectomies. More than 50% of each medial facet was preserved bilaterally to maintain spinal stability.

RESULTS

Postlaminectomy thoracolumbar kyphoses developed in all 10 patients (100%). The postlaminectomy kyphoses ranged from 78 degrees to 135 degrees (mean 94 degrees ). All patients underwent spinal fusions with instrumentation, performed from 10 months to 2.6 years after the decompressions, to stabilize the kyphoses.

CONCLUSIONS

Skeletally immature achondroplasts are at high risk for developing postlaminectomy thoracolumbar kyphoses. Therefore, concurrent spinal fusion is indicated in skeletally immature achondroplasts who undergo thoracolumbar laminectomies of at least 5 levels.

Isolated subaxial cervical spine stenosis in achondroplasia

Although isolated subaxial cervical spine stenosis in achondroplasia is less common than narrowing at the foramen magnum, thoracolumbar junction, or lumbar spine, it should be recognized as a distinct entity. These congenital changes usually become symptomatic when combined with degenerative changes in early adult life. Yearly monitoring of adult achondroplastic patients for signs and symptoms of cervical myelopathy or radiculopathy is recommended. When this develops, early surgical decompression should be considered, as these patients generally do not respond well to nonoperative treatment. The altered anatomy and small size make these cases particularly challenging. A thorough history and examination and complete diagnostic testing are necessary to gain an understanding of the exact etiology of the symptoms. Wide laminectomies and foraminotomies are then usually required to decompress the spinal cord and nerve roots. Fusion using internal fixation may be required to stabilize the spine if excessive bone is removed. (Curr Surg 57:354-356)

Reoperation for spinal restenosis in achondroplasia

The characteristics of spinal restenosis in achondroplasia and its treatment are evaluated in this study. Radiologic and surgical findings were correlated to establish the causes of achondroplastic spinal restenosis and the benefits of its therapy. Eight patients (five men, three women) with spinal restenotic complications of achondroplasia were studied. The most common neurological sign of recurrent stenosis was impaired motor function. The mean interval between the most recent surgeries was 8.2 years (9.5 years for surgeries at the same levels). The most common causes of recurrent stenosis were facet hypertrophy and disk disease. The complications were a dural tear and cerebellar hemorrhage in one patient and transient neurological deterioration in another. One patient died after operation. Restenosis can occur many years after original decompression in the achondroplastic spine, and repeated operation can successfully lessen pain and neurological symptoms in most patients.

Sleep-disordered breathing in children with achondroplasia

OBJECTIVE

Our objective was to characterize sleep-disordered breathing in 88 children with achondroplasia aged 1 month to 12.6 years.

RESULTS

At the time of their initial polysomnography, five children had previously undergone tracheostomy, and seven children required supplemental oxygen. Initial polysomnography demonstrated a median obstructive apnea index of 0 (range, 0 to 19.2 apneas/hr). The median number of central apneas with desaturation per study was 0.5 (0 to 49), the median oxygen saturation nadir was 91% (50% to 99%), and the median peak end-tidal pCO2 was 47 mm Hg (36 to 87 mm Hg). Forty-two children (47.7%) had abnormal initial study results, usually caused by hypoxemia. Two children with severe obstructive sleep apnea eventually required continuous positive airway pressure therapy, and three additional children required tracheostomies.

CONCLUSIONS

(1) Children with achondroplasia often have sleep-related respiratory disturbances, primarily hypoxemia. (2) The majority do not have significant obstructive or central apnea; however, a substantial minority are severely affected. (3) Tonsillectomy and adenoidectomy decreases the degree of upper airway obstruction in most but not all children with achondroplasia and obstructive sleep apnea. (4) Restrictive lung disease can present at a young age in children with achondroplasia.