Pediatric Surgical Issues

From Current Concepts in General Surgery 2009, sponsored by the University of New Mexico School of Medicine, Albuquerque

Educational Objectives

The purpose of this program is to improve management of scoliosis and cranial deformities. After hearing and assim­ilating this program, the listener will be better able to:

1.   Describe the evidence showing that bracing is the only effective nonsurgical treatment for scoliosis.

2.   Discuss the benefits of pedicle screws in surgical treatment of scoliosis.

3.   Explain the difference between plagiocephaly and craniosynostosis (CS).

4.   Identify the syndromes most commonly associated with CS.

5.   List the treatment options for cranial deformities.

Faculty Disclosure

In adherence to ACCME Standards for Commercial Support, Audio-Digest requires all faculty and members of the plan­ning committee to disclose relevant financial relationships within the past 12 months that might create any personal con­flicts of interest. Any identified conflicts were resolved to ensure that this educational activity promotes quality in health care and not a proprietary business or commercial interest. For this program, the following has been disclosed: Dr. Bosch re­ceives research support from Medtronic Spine. Dr. Marchand and the planning committee reported nothing to disclose. In his lecture, Dr. Bosch presents information related to the off-label or investigational use of a therapy, product, or device.

Acknowledgements

Drs. Bosch and Marchand were recorded at Current Concepts in General Surgery 2009, held September 2-4, 2009, in Albuquerque, NM, and sponsored by the University of New Mexico School of Medicine. The Audio-Digest Founda­tion thanks the speakers and the University of New Mexico School of Medicine for their cooperation in the produc­tion of this program.

Pediatric Spine Surgery

Patrick Bosch, MD, Assistant Professor, Pediatric Orthopaedic Surgery, University of New Mexico Health Sci­ences Center, Albuquerque

Scoliosis

Definition: lateral deviation of spine >10^o on anteroposterior (AP) or posteroanterior (PA) film

Etiology: neuropathic  —  usually caused by upper motor neuron lesion (syringomyelia; tethered spinal cord; tumors; cerebral palsy) or lower motor neuron lesion (myelomeningocele; spina bifida; spinal muscular atrophy; trauma [eg, gunshot wounds may cause paralytic scoliosis]); other etiologies include muscle, connective tissue, or osteo­genic disorders; iatrogenic  —  sternotomy or thoracotomy; laminectomy; congenital conditions  —  vertebral ab­normalities; rib or chest abnormalities (may be more common than previously recognized); idiopathic  —  accounts for 80% of pediatric surgical cases; right thoracic-left lumbar curve typical idiopathic pattern; typical phenotype tall thin girl; diagnosed by exclusion; most studies show presurgical magnetic resonance imaging (MRI) unnecessary, but most surgeons obtain MRI for medicolegal reasons; infantile  —age of onset <3 yr; »50% resolve spontaneously (does not occur with most other forms of scoliosis); resolving type usually associated with rib-vertebral angle difference <20^o; if difference >20^o, condition most likely progressive and will require treat­ment; juvenile  —  young adolescent scoliosis; clear genetic component (1 in 10 patients have family history); found predominantly in girls, especially when curvature >30^o to 40^o; curves <20^o found with equal frequency in boys and girls; now considered growth abnormality (crooked growth of spine)

Early-onset scoliosis: new term encompassing early severe deformity that interferes with lung development; in­cludes early infantile, idiopathic, congenital, and iatrogenic forms

Thoracic insufficiency syndrome: usually associated with deformities on axial and sagittal planes; includes kypho­sis and thoracic lordosis; »50% of chest capacity achieved by 10 yr of age; number and size of adult alveoli thought to be achieved by 8 yr of age; age at which lung capacity sufficient to sustain adult life unknown; condi­tion defined as lung function insufficient to sustain adult life (patients die young)

Diagnosis: made on examination; features include trapezial fullness; uneven shoulders; thoracic prominence  —  axial rotation of curve when patient bends forward often most sensitive indicator; lumbar musculature rotates simi­larly, but does not have same lateral excursion as ribs (makes finding more subtle); waist asymmetry; discrepancy in leg length creates apparent (false) scoliosis; scoliosis with lumbar curve creating waist asymmetry creates ap­parent leg length discrepancy

Examination: determine whether curvature exists and effect on patient (symptoms); determine whether future prob­lems expected due to curvature; progression critical issue (driven by growth); in girls, peak growth velocity oc­curs during year before menarche; Risser sign (ossification of iliac apophysis) poor indication because abnormality may not appear until after peak growth finished; Tanner-Whitehouse database  —  epiphysis of dis­tal phalanx widens slightly relative to metaphysis close to time of peak growth velocity; most accurate predic­tor of scoliosis progression; general rules  —scoliosis progresses to magnitude requiring treatment in 1 in 5 premenarchal skeletally immature patients with curve <20^o; if curve >20^o, two-thirds progress to treatment magnitude; if patient >1 yr past menarche, with curve <20^o, little need for treatment; if curve 20^o to 29^o, »1 in 4 require treatment; in study of patients followed for »50 yr, curves of <30^o at maturity rarely progressed (sur­gery not indicated); curves >50^o at maturity continued to worsen at rate of 1^o to 2^o per year and presented prob­lems later in life

Genetic test: private company now using single-nucleotide polymorphisms (SNPs) to assign score and determine child’s prognosis; proprietary test (promising, but not yet peer-reviewed)

Current approach: wait for scoliosis to progress, then operate

Natural history: disrupts truncal harmony, mobility, and function; may disrupt stability and balance; idiopathic sco­liosis never associated with spinal cord compromise; lungs and heart remain unaffected (demonstrable compromise in pulmonary function only with curves greater than 70^o to 80^o); results of pulmonary function tests variable (reli­ability uncertain); patients may experience pain and functional impairment; surgery largely for cosmesis

Classification systems: King-Moe  —  developed in 1980s; helped identify candidates for selective fusion; Lenke  —more comprehensive; now used by all orthopedic surgeons; based on structural curve; currently, classifications based on 2-dimensional radiographs (deformity 3-dimensional)

Nonoperative treatment: includes bracing, exercise, manipulative treatments, and gene therapy

Bracing: only nonoperative method supported by any evidence, but data poor; 1995 Swedish study shows bracing decreased rate of progression, but did not correct curve; never demonstrated effective in predominantly male population; Bracing in Adolescent Idiopathic Scoliosis Trial (BrAIST)  —  first orthopedic clinical trial funded by National Institutes of Health; randomized prospective partially blinded study; ideal bracing candidates random­ized to bracing or no bracing; goal to determine true value of bracing; patient accrual difficult

Surgical treatment: goals  —  avoid complications; prevent curve progression; straighten curve as much as possible

Treatment principles: loosen spine with facetectomy and discectomy; use implant to correct and hold curve (trac­tion sometimes indicated); uninstrumented fusion and Harrington rods no longer used (first generation tech­niques)

Pedicle screws: preferred currently (third- or fourth-generation technique); associated with »70% coronal correc­tion (compared to 50% with older constructs); minimal loss, reduction, or drift; permits derotation of curve (not possible with hooks); good cosmetic improvement; allow control over spinal column; improve fixation; enable reduction maneuvers; permit performance of complex osteotomies; reduce need for anterior surgery; selective thoracic fusion  —  fusing only thoracic curve and expecting other curve to correct; controversy  —  aggressive straightening with pedicle screws may create imbalance in lower compensatory curve; “maybe less is more”; no data suggest current 70% correction better than older 50% correction; balance probably key; better to preserve mobile segments with slight curve than to achieve complete straightening with more fusion of lumbar spine

Treatment of early-onset scoliosis: goals to preserve or encourage growth, maintain pulmonary development, and control curve; casting now popular, but results questionable; growing rods regaining popularity, with good out­comes; vertical expanding prosthetic titanium ribs also associated with good results, although overused

Craniosynostosis

Erich P. Marchand, MD, Associate Professor of Neurosurgery, University of New Mexico Health Sciences Cen­ter, Albuquerque

Common terms: plagiocephaly  —  although strict definition is asymmetric deformity of head related to coronal or lambdoid synostosis, term used to encompass all types of cranial deformities; in actual practice, usually refers to non-craniosynostotic deformities of head (most common presentation); craniosynostosis (CS)  —  premature clo­sure of cranial suture

Types of CS: primary  —  directly related to bone growth; secondary  —  associated with neurosurgical intervention for children with maldevelopment of brain

Background: incidence and prevalence difficult to determine; until 1992, incidence of plagiocephaly »1 per 2500 live births; after 1992, saw increase in incidence of non-CS cranial deformities (due to “Back to Sleep” campaign promoted by American Academy of Pediatrics to prevent sudden infant death syndrome); speaker received »10 referrals per week for evaluation for CS (with no genuine cases); after education of clinicians, referrals now only »2 per wk

Cranial sutures: metopic  —  runs to front of forehead; coronal  —  run to either side; sagittal  —  runs down middle; lambdoid  —  run posteriorly; squamosal  —  visible on side view (not involved in CS); smaller sutures also visible, but not involved in CS

Noncraniosynostotic deformities: infants rarely born with condition; usually starts developing at 2 to 3 mo of age; fetus’ position in mother’s pelvis implicated in many cranial deformities (can mold or constrain head growth); con­genital torticollis can increase risk; diagnosis  —  check cervical spine for normal range of motion; obtain history of patient’s sleeping position; typical deformity characterized by flattening of head on one side (often due to favored sleeping position); distinguishing from CS critical issue; typically, deformity characterized by long axis of head ex­tending from one side of forehead to contralateral occipital region; skull base deformable; external auditory canals at different levels; no objective measurements; classified as mild, moderate, or severe for purposes of recommend­ing treatment

Treatment: prevention; physical therapy for neck; treat strabismus if present; helmets often used; surgery “essen­tially unknown and probably not required”; instruct parents on correct positioning for putting babies to sleep; if necessary, change crib position so baby sees parents more easily; devices that keep baby on side fairly effective; physical therapy usually resolves torticollis in few months, although deformation may have already started

Helmets: custom-made; constrain growth of long axis of head, while leaving gaps on other sides; worn 23 hr/day; pushes head into more normal position; usually well tolerated; most patients respond quickly; helmets made us­ing computer-generated 3-dimensional model of baby’s head; same method used for tracking progress

Posterior plagiocephaly: distinguish from lambdoid synostosis (rare condition) through clinical history, and physi­cal examination (PE); x-rays and computed tomography rarely needed

Craniosynostosis: true pathologic entity (unlike plagiocephaly); types  —  sporadic (most cases), familial (»2% of sagittal cases; »8% of unilateral coronal), and syndromic (most severe); >50 syndromes include CS in diagnostic criteria; most common include Apert syndrome (bicoronal CS, polysyndactyly, and midface deformities); Crou­zon syndrome (bicoronal and midface abnormalities); Pfeiffer syndrome (unusual); developmental delay and cognitive dysfunction uncommon

Pathophysiology: regulatory processes determine when sutures close; extracellular matrix determines state of su­ture; different receptors and growth factors present at different sutures; premature closure results from growth factor-receptor imbalance in extracellular matrix; genetically determined receptor abnormality for fibroblast growth factor (FGF; regulated by prostaglandin F₂a [PGF_2a]) found in Apert and Crouzon syndromes; receptors do not respond normally to FGF, which results in premature closure of bone; occurs mostly at coronal suture; TWIST-1 gene abnormality seen in Saethre-Chotzen syndrome also affects coronal suture through cascade of ab­normalities; sporadic cases  —  animal studies suggest that cranial growth constriction creates FGF imbalance, which may be final common pathway in syndromic and sporadic cases

Clinical presentation: syndromic cases usually involve multiple sutures, facial bones, and possibly other bony ab­normalities; most sporadic cases involve single suture; uncorrected deformities associated with significant psy­chosocial problems; cognitive and perceptual impairment more common than in general population, although most patients cognitively normal (cause unknown); secondary effects  —  increased intracranial pressure, which sometimes leads to impaired vision; formerly, patients with severe deformity often blind from papilledema by early school age; rare with single-suture CS; best results with early treatment

Diagnosis: usually early postnatal; PE generally sufficient; imaging studies unnecessary; “the shape of the head re­ally tells the tale”; closed cranial suture restricts perpendicular growth; sagittal  —  most common; associated with long narrow head shape, with palpable ridge over sagittal suture, and small-to-absent anterior fontanelle; coronal  —second most common type; highly asymmetric; involves face; metopic  —  relatively common; charac­terized by trigonocephaly, including abnormally narrow placement of eyes; lambdoid  —  rare; multisuture  —  causes severe deformity; surgery often indicated to protect brain as well as to correct deformity

Surgery: performed to correct deformity; however, condition usually does not worsen if uncorrected (stabilizes at »6 mo); correction rarely complete, but improvement seen; consists of opening closed bone; with sagittal synos­tosis, sagittal suture removed; cuts in other bones encourage remodeling of skull; current trend minimally inva­sive surgery using crosswise anterior and posterior incisions, creating space under scalp, and removing bone; early surgery, followed by molding helmet, produces excellent results; more aggressive surgery indicated for older children; may include mobilizing supraorbital rim or other bone and use of absorbable plates; helmet worn after surgery until »18 mo of age; most serious complications include blood loss; occasionally, minor eye com­plications occur; cosmetic result usually excellent, although never perfect; »2% of patients require reoperation for restenosis; »5% require reoperation for persistent cranial defects; no data on functional recovery (psychoso­cial issues)

Suggested Reading

Di Rocco F et al: Evolution in the frequency of nonsyndromic craniosynostosis. J Neurosurg Pediatr 4:21, 2009; Goldberg CJ et al: Scoliosis: a review. Pediatr Surg Int 24:129, 2008; Keshavarzi S et al: Variations of endoscopic and open repair of metopic cra­niosynostosis. J Craniofac Surg 20:1439, 2009; Losee JE, Mason AC: Deformational plagiocephaly: diagnosis, prevention, and treatment. Clin Plast Surg 32:53, 2005; McIntosh BC et al: Utilization of postcranioplasty skull molding caps in the treatment of Apert syndrome. J Craniofac Surg 19:1566, 2008; Mehta SS et al: Pedicle screw-only constructs with lumbar or pelvic fixation for spinal stabilization in patients with Duchenne muscular dystrophy. J Spinal Disord Tech 22:428, 2009; Sanders JO et al: Predicting Scoliosis Progression from Skeletal Maturity: A Simplified Classification During Adolescence. J Bone Joint Surg 90:540, 2008; Teichgraeber JF et al: Microscopic minimally invasive approach to nonsyndromic craniosynostosis. J Craniofac Surg 20:1492, 2009; Vialle R et al: Surgical treatment of severe thoracic scoliosis in skeletally mature patients. Orthopedics 31:218, 2008; Wein­stein SL et al: Adolescent idiopathic scoliosis. Lancet 371:1527, 2008; Wick JM et al: Infantile and juvenile scoliosis: the crooked path to diagnosis and treatment. AORN 90:347, 2009; Woods RH et al: Reoperation for intracranial hypertension in TWIST1-con­firmed Saethre-Chotzen syndrome: a 15-year review. Plast Reconstr Surg 123:1801, 2009.