Dwarf with dual spinal kyphotic deformity at the cervical and dorsal spine unassociated with odontoid hypoplasia: Surgical management.

Morquio's syndrome is associated with systemic skeletal hypoplasia leading to generalized skeletal deformation. The hypoplasia of odontoid process is frequent association, which is responsible for atlantoaxial dislocation causing compressive myelopathy. However, development of sub-axial cervical kyphotic deformity unassociated with odontoid hypoplasia is extremely rare, and coexistence of dorsal kyphotic deformity is not reported in the western literature till date and represents first case. Current case is 16-year-old boy, who presented with severe kyphotic deformity of cervical spine with spastic quadriparesis. Interestingly, he also had additional asymptomatic kyphotic deformity of dorsal spine; however, odontoid proves hypoplasia was not observed. He was only symptomatic for cervical compression, accordingly surgery was planned. The patient was planned for correction of cervical kyphotic deformity under general anesthesia, underwent fourth cervical corpectomy with resection of posterior longitudinal ligament and fusion with autologous bone graft derived from right fibula, which was refashioned approximating to the width of the corpectomy size after harvesting and fixed between C3 and C5 vertebral bodies and further secured with anterior cervical plating. He tolerated surgical procedure well with improvement in power with significant reduction in spasticity. Postoperative X-ray, cervical spine revealed complete correction of kyphotic deformity cervical spine. At follow-up 6 months following surgery, he is doing well. Successful surgical correction of symptomatic cervical kyphotic deformity can be achieved utilizing anterior cervical corpectomy, autologous fibular bone graft, and anterior cervical plating.

Introduction

Morquio's syndrome also called as mucopolysaccharidosis Type IV is autosomal recessively inherited genetic disorder.[12] Its incidence is estimated about 1 case per 200,000 population.[3] Morquio's syndrome is a lysosomal storage disorder with specific defect in degradation of keratin sulfate leading to progressive accumulation and deposition of mucopolysaccharidoses in the arteries, eyes, joints, and skeleton, which leads to progressive damage to organs. A newborn may appear healthy, however with growth, the child can develop multiple skeletal abnormalities, that is, short stature, short neck, barrel chest, hypoplasia of odontoid, hyper mobile joints, and defects of mid-face hypoplasia with mandibular protrusion are common associations.[4] The odontoid hypoplasia causes atlantoaxial dislocation, which leads to causing compressive myelopathy, a common association of Morquio's syndrome. The current case had conspicuously absence of atlantoaxial dislocation, instead had marked cervical kyphotic deformity. Presence of skeletal, spinal deformity along with restricted lung expansion and reduced tidal volume causes difficulty during intubation and also presents an anesthetic challenge during perioperative period.[1]

Case Report

A 16-year-old boy, diagnosed case of Morquio's syndrome, as he was on regular follow-up with pediatrician at our institute and diagnosed as mucopolysaccharidosis Type 4a. He presented with progressive spastic quadriparesis for last 1 year and become bed ridden for 2 months prior to current admission in the hospital. The boy had short neck with kyphotic cervical and thoracic kyphoscoliotic deformity [Figure 1]. The examination on admission revealed cachectic, frail boy weighted 22 kg. The typical phenotypes of the Morquio's syndrome, that is, short stature, short neck, stubby nose, teeth widely placed, broad mouth, barrel chest with and dwarf body with presence of palpable kyphotic deformity of cervical and thoracic spinal region were noted. Neurological evaluation revealed generalized hypertonia of all limbs with spastic quadriparesis with power - 4/5 at upper limbs and 3/5 at both lower limbs with exaggerated deep tendon reflexes, bilateral extensor Babinski responses, presence of ill sustained patellar, and ankle clonus.

Figure 1

Clinical photograph of 16-year-old boy showing presence of two separate kyphotic deformity cervical and dorsal region

X-ray of cervical spine revealed the presence of severe kyphotic deformity at second to sixth cervical vertebral level with the apex of the kyphosis at C4 level causing hump [Figure 2]. Magnetic resonance imaging (MRI) scan of cervical spine, sagittal section T2-weighted image revealed severe spinal canal stenosis and associated spinal cord compression and myelo-malacia, presence of severe cervical kyphotic deformity [Figure 3], and whole spine screening MRI scan revealed additional kyphotic spine deformity was also noticed at D10–12 level in Figure 4.

Figure 2

X-ray cervical spine, lateral view post cervical traction showing gross cervical kyphotic deformity

Figure 3

Magnetic resonance imaging cervical spine, saggital section, T2-weighted image showing presence of severe cervical kyphotic deformity at C3–C5 with the apex of the kyphosis at C4 vertebra and associated myelomalacia of the cervical spinal cord

Figure 4

Whole spine screening magnetic resonance imaging, sagittal section, T2-weighted image showing dual kyphotic deformity at the cervical and thoracic region with severe canal stenosiscervical

Intervention

Cervical traction was applied, gradually weight of traction increased up to 4 kg and continued for 5 days, which only led to slight reduction in the cervical kyphosis subsequently, he was taken-up for planned anterior cervical corpectomy, strut fibular autologous graft, and anterior cervical plating. He was intubated using video laryngoscope with skull traction in situ, a vertical incision in the neck at site marked under image intensifier was made, platysma divided, subcutaneous dissection carried out and corridor made between sternocleidomastoid muscle and carotid sheath retracted laterally and esophagus and trachea medially. The vertebral body level was localized with intraoperative image intensifier and corpectomy of C4 was carried out with Midas drill. The texture of vertebral body was extremely soft and highly vascular. The posterior longitudinal ligament was also removed to completely release compression of the thecal sac. Autologous fibular graft was harvested from right leg and fashioned approximating to the width of corpectomy tunnel size and fixed between C3 and C5 vertebra and further secured with anterior cervical plate and cortical screws. Intraoperative X-ray of cervical spine revealed complete correction of cervical kyphosis with graft in proper position and well placed screws [Figure 5]. He was extubated after surgery. Postoperative period was uneventful. He is doing well at 5 months follow-up after surgery.

Figure 5

X-ray, cervical spine, lateral view showing complete correction of cervical spine kyphotic deformity using autologus fibular graft and anterior cervical plate with screws fixation (intraoperative)

Discussion

In 1929, Morquio and Brailsford described Morquio Brailsford syndrome characterized by mucopolysaccharidoses Type IV, with recessive inheritance, has two types. The Type IV a variety is caused due to deficiency of N-acetyl galactosamine sulfatase enzyme, while Type IV b attributed to inadequate production of the β-galactosidase enzyme.[2] These enzymes are responsible for breaking down keratin sulfate sugar chain, a long strand of sugar molecules. However, deficiency of enzymes is responsible for to abnormal deposit of large amounts of glycosaminoglycans in the different organs of the body and causing progressive damage.[5] Morquio's syndrome is usually associated with generalized hypoplasia of bone, which leads to multiple skeletal abnormalities and commonly includes short stature, hypoplasia of mid-face leading to mandibular protrusion, short neck, widely space teeth, barrel chest, hyper mobile joints, are well known associations. The visceral abnormality includes hepatomegaly, cardiac abnormality, restricted lung expansion, ventilation-perfusion mismatch pulmonary hypertension, and development of cor pulmonale in the advanced cases. Most common spinal anomaly is odontoid hypoplasia, which causes spinal cord compression and myelo-malacia. Morquio's syndrome with cervical instability also presents an anesthesia challenge during perioperative phase.[1]

Short stature may cause psychological stress in addition to physical limitation. It is also a pointer of disease or disability. Short stature is defined as a height that is two or more standard deviations below the mean for age and gender within a given population residing in a demarcated geographical region.[6] Short stature can be classified into either disproportionate or proportionate. Disproportionate dwarf is characterized by presence of relatively larger or smaller body parts typically caused by genetic disorders, which commonly involves bone or cartilage development, as commonly observed skeletal dysplasia as short limb results due to reduced growth rate of the limbs, e.g., hypochondroplasia and achondroplasia. A variety of disproportionate dwarf may be associated with relatively shorter trunk e.g., spondyloepiphyseal dysplasia.[67]

On the other hand, proportionate dwarf patients have normally proportioned body parts, but unusually small stature. Extreme dwarfism with proportional body parts are mostly caused by hormonal deficiency disorder e.g., growth hormone deficiency, pituitary dwarfism.[7] Further, a subset of proportional dwarf stature may have generalized short stature with proportional shortened limbs and trunk e.g., Type IV-osteogenesis imperfecta.

As spinal involvement causes great morbidity in mucopolysaccharidosis in the form of compressive myelopathy, a detailed systematic assessment and proper management of spinal instability, spinal stenosis, and spinal cord compression should be attempted at the earliest, to prevent irreversible neurological damage.[8910] Aim of surgical management of spinal deformity in Morquio's syndrome is bony and soft tissue decompression of spinal cord, bony decompression to relieve spinal canal stenosis, correction of spinal deformity, spinal stabilization by bony reconstruction with bone graft.

An early posterior cervical fixation is also advocated to prevent progressive neurological deterioration; hence prophylactic occipitocervical fusion is usually advocated in the patients with atlantoaxial mechanical instability contributing to the development of compressive myelopathy.[23] However, cervical kyphotic deformity is an extremely rare association and only few such cases are reported in literature.[4] Our case is unique as cervical cord compression resulted from an uncommon degree of cervical kyphotic rather than commonly observed compression at C1–C2 level in cases with Morquio's syndrome. More so, our case had double deformity; such cases are not reported in Western literature till date.

Corpectomy and stabilization with fibular bone grafts and anterior cervical plating management of such cases possess special anesthetic challenge, so awake, video laryngoscope guided intubation, using flexometallic endotracheal tube and cervical collar in situ and cervical traction to avoid the development of fresh neurological deficits during endotracheal intubation procedure.[5] Surgical decompression of the spinal cord was accomplished by anterior approach using single level corpectomy. In children harvesting of autologous graft is challenge as iliac bone is not well developed, so fibula offers a viable alternative, and used in the current case. Preventive screening and X-ray of craniovertebral junction including detailed clinical and neurological examination was advocated by Taccone et al. for screening of dwarf child.[8] Further author advocated inclusion of cervical spine X-ray in screening of every case is must and if possible whole spine should be evaluated in the screening program.

Conclusions

Morquio's syndrome is associated with generalized skeletal hypoplasia. The hypoplasia of odontoid process is very common association, causing atlantoaxial dislocation. Authors advocate screening of whole spine as rarely may have additionally associated sub-axial spinal compression although uncommon, but search must be carried out to for the possible existence of dual kyphotic deformity of cervical and dorsal spine. A detailed systematic assessment after spinal screening for possible existence of spinal instability, spinal stenosis, and spinal cord compression and accordingly management should be provided at the earliest possible opportunity to prevent irreversible neurological damage. Successful correction of cervical kyphotic deformity can be carried out with anterior cervical corpectomy and autologous fibular strut graft harvested instead of iliac crest. Further, theses cases during surgery need assistance of a skilled anesthesiologist for the management of airway and cervical spine instability during perioperative period.

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Conflicts of interest

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