Neurofibromatosis and

the spine

Shekar Roopan

Spinal Unit

King Dinuzulu Hospital Complex

Introduction

• Multisystem disease affecting all three germ lines

(neuroectoderm, mesoderm and endoderm)

• Four varieties exist

• Neurofibromatosis 1 (NF1) the most common

History• 1847 - Virchow

• 1882 - von Recklinghausen

• The elephant man - Joseph Carey Merrick

Classification

• Neurofibromatosis 1 - Peripheral neurofibromatosis

• Neurofibromatosis 2 - Central neurofibromatosis

• Segmental neurofibromatosis

• Schwannomatosis

Epidemiology and genetics

• Autosomal dominant

• 50% of cases spontaneous mutations

• Gene located on long arm of chromosome 17 (NF1)

• Prevalence 1:4000

• First peak - 5-10 years

• Second peak - 36-50 years (75% of clinical problems

due to malignancy)

Diagnostic Criteria

1. ≥6 cafe-au-lait spots (>5mm prepubertal, >15mm post pubertal)

2. ≥2 neurofibromas/≥1 plexiform neurofibroma

3. Axillary/inguinal freckling

4. Optic glioma

5. ≥2 Lisch nodules

6. Osseous lesion (sphenoid dysplasia/long bone cortex thinning)

7. NF1 in first degree relative

Consensus development conference of the National Institute of Health; 1987

Cafe-au-lait spots

• 90% of patients

• Melanotic in origin

• Found in skin areas not

exposed to the sun

• Under 5 years, 2 cafe au lait

spots are common and

normal

Whitehouse D; Diagnostic value of cafe-au-lait spot in children; Arch Dis Child;1966

Neurofibromas

• Fibroma molluscum -

small neurofibroma in

the subcutis

• Plexiform

neurofibroma - “bag

of worms” feeling

Axillary and inguinal freckling

• diffuse, small hyper pigmented

spots (2-3mm diameter)

• 40% patients - axillary freckling

Optic Glioma

• Account for 2-5% of all brain tumours in childhood

• 70% of cases are in NF1

Lisch Nodules

• slightly raised, well

circumscribed hamartomas

on the iris

• Present in 90% of patients

>6 years

• Specific to NF1

Skeletal associations

• Generalised - osteoporosis, osteomalacia, short

stature, macrocephaly

• Focal - spinal deformities, long bone and sphenoid

wing dysplasias, chest wall and dental

abnormalities, cystic osseous lesions

Other associations

• Cardiovascular - pulmonary stenosis, hypertension

• Renal

• renal artery stenosis - 2% NF1 patients

• phaeochromocytoma - 2% NF1 patients

Spinal deformities

• Cause remains unknown

• Aetiological theories:

• infiltration of bone by localised neurofibromas,

metabolic bone deficiency, osteomalacia,

endocrine disturbance and mesodermal dysplasia

- inconclusive

Cervical spine

• Rarely reported in literature

• Presentation: asymptomatic, pain, deformity, neck

mass, neurological deficit, atlanto-axial dislocations

• Kyphosis is the most common abnormality

• All NF1 patients require x-ray c-spine before a

general anaesthetic/skull traction

Neurofibromatosis of the cervical spine; JB Craig, S Govender; JBJS Br; 1992

Thoracolumbar spine

• Scoliosis:

• Dystrophic

• Non dystrophic

• Kyphoscoliosis

• Lordoscoliosis

• Spondylolisthesis

Scoliosis

• Commonest spinal deformity in NF1 (10-20%)

• Cause of deformity unknown - ?secondary to

osteomalacia, localised neurofibromatous tumour

eroding bone, endocrine disturbances and/or

mesodermal dysplasia

• Dystrophic/non dystrophic

Non dystrophic scoliosis

• Commonest spinal deformity

• Involves 8-10 spinal segments

• Usually convex to the right

• Similar to idiopathic scoliosis

Dystrophic scoliosis

• Less common

• Usually short segment, sharply

angulated curve

• 3 or more dystrophic features on

x-ray

• The more severe the dystrophic

changes the greater the chance

the curve will deteriorate

Dystrophic features• rib pencilling

Dystrophic features• posterior vertebral scalloping

Dystrophic features

• vertebral rotation

• widening of intervertebral foramina

• lateral vertebral scalloping

Dural ectasia

• Circumferential dilation of dural sac

• Contains CSF and brownish

proteinaceous material

• Due to abnormal pressure phenomenon

• Expanding dura erodes surrounding bony

structures, widening the spinal canal and

may destabilise the vertebral elements

• MRI for all dystrophic curves prior to

surgery

Modulation• Transformation of non dystrophic curve to dystrophic

or addition of further dystrophic features to a

dystrophic curve

• MRI studies have questioned the theory of

modulation

• Characterisation of curve as dystrophic or not

should be based on x-ray and MRI

Tsirikos et al; Assessment of vertebral scalloping in NF1 with plain

radiography and MRI

AH Crawford et al; Spine deformity preview issue; Sept 2012

Kyphoscoliosis

• Curve of 50 degrees or more in sagittal plane with

any degree of coronal deformity

• Can present with paraplegia (spinal cord elongation,

rib protrusion into canal and intraspinal tumours)

• Flexibility of curve needs to be assessed

Lordoscoliosis

• Not common

• Causes respiratory compromise and mitral valve

prolapse

Spondylolisthesis

• Rare

• Usually associated with pathologic elongation of

pedicles and pars interarticularis by lumbosacral

foramina neurofibromas or dural ectasia with

meningoceles

• Combined anterior and posterior fusion

• Postoperative immobilisation until fusion is solid

Approach• History - establish diagnosis of NF1

• Examination - define deformity, ascertain level and assess

flexibility; neurological deficit; exclude cardiovascular and

renal involvement; exclude pulmonary compromise

• Investigations

• Bloods - FBC, U&E, urinary catecholamines, PFT,

Crossmatch

• X-rays, CT, MRI - Dystrophic/Non dystrophic, curve

magnitude, intraspinal lesions/changes; c-spine

ScoliosisNon-Dystrophic

Curve

<25

Observe

25-40

Brace

40-60

PSF

>60

ASF+PSF

AH Crawford; Neurofibromatosis: etiology, commonly encountered spinal deformities,

common complications; Spine deformity preview issue; 2012

ScoliosisDystrophic

Curve

<20

Observe

20-40

PSF

>40

ASF+PSF

>90

AR+CFT

+PSF

AH Crawford; Neurofibromatosis: etiology, commonly encountered spinal deformities,

common complications; Spine deformity preview issue; 2012

KyphosisNeurology

Curve

50-70

ASF+PSF

Pre-op

CFT

>70

AR+CFT

+PSF

No Yes

Flexible

NoYes

ASF+PSF

AR+CFT

+PSF

AH Crawford; Neurofibromatosis: etiology, commonly encountered spinal deformities, common complications;

Spine deformity preview issue; 2012

Postoperative

• Immobilsation postoperatively

• Fusion mass assessed at 6 months by CT scan

Complications

• Pseudoarthrosis

• Crawford - 15% incidence

• Sirois and Drennan - 38% incidence

• Prevention - decortication, abundant autogenous

bone grafting, segmental instrumentation,

meticulous resection of pathologic soft tissue,

orthotic immobilisation until fusion mass seen on

CT, ?rhBMP-2

Complications

• Paraplegia:

• cord compression secondary to spinal deformity,

rib penetration, intraspinal tumours

• Younger patients - usually spinal deformity

• Older patients - usually tumours

Complications

• Rib protrusion

• Usually occurs on convex of curve

• Important surgical consideration for correction

• Ostectomy of 2.5-5cm of protruding rib indicated

at posterior fusion

Complications

• Bleeding

• Dural leaks

Conclusion

• Scoliosis most common spinal deformity in NF1

• Multidisciplinary treatment strategy is needed

• Management depends on recognition of non-

dystrophic or dystrophic curves

• Post operative immobilisation is always

recommended

Thank You

• Orthopaedic complications of von Recklinghausen's

disease in children. A.H Crawford. Current Orthopaedics

01/1996

• Neurofibromatosis: Etiology, Commonly Encountered

Spinal Deformities, Common Complications and Pitfalls of

Surgical Treatment; A.H. Crawford et al. / Spine Deformity

Preview Issue (September 2012)

• Spinal deformity in neurofibromatosis type-1: diagnosis

and treatment; Athanasios I. Tsirikos; Eur Spine J. Jun

2005

References