NF

Epidemiology

 

2% scoliosis patients have NF

 

10 - 30 % NF patients have spinal deformity

- most common skeletal manifestation

- mostly non dystrophic variety

 

Types

 

A.  Non dystrophic

- vertebral wedging, angulation and rotation

- very similar to idiopathic scoliosis

- right thoracic

 

B.  Dystrophic

 

Cause

- may be due to intraspinal lesions such as tumours, meningoceles and dural ectasia

- can simply be bony dysplasia

 

Characterised by

- short segments, sharp angulation with severe apical rotation

- scalloping posterior margins

- widening of the spinal canal

- enlargement of neural foramina

- widened interpedicular distance

- thinned defective pedicles and lamina

- paraspinal mass

- rotation of ribs - 'pencilling'

 

Other problems

 

Cervical spine kyphosis

 

Atlantoaxial dislocation 

- has been reported in five patients

- flexion and extension views are important in assessing cervical instability

- needed pre-op

 

Kyphosis

- marked acute posterior angulation

- can develop myelopathy and even paralysis

 

Intraspinal Tumours

 

Dural Ectasia

- circumferential dilatation of dural sac

- contains CSF and brown material

- erodes osseous structures

- very thin lamina

- can cause great angular deformity

- may have multiple dumbbell appearances

 

Dumbbell lesion

- single neurofibroma

 

Meningocoeles / pseudomeningocoeles

 

Management

 

Non Operative Management

 

Brace treatment

 

Not been effective in dysplastic curves

Can use early in non dysplastic

 

Operative Management

 

Non dystrophic

 

Issues

 

Recommend posterior fusion for progressive

- lower threshold for surgery than in idiopathic

- potential for progression much higher

 

Surgery as for idiopathic

 

Idiopathic

 

Brace 20 - 35o

Surgery > 35o

 

Dystrophic

 

Issues

 

A.  All dystrophic curves need MRI to assess intraspinal lesion

 

B.  All need C spine screening before surgery

- these patients also often have cervical spine abnormalities and instability

 

C.  Incidence of pseudoarthroses ranges from 6% to 38% with isolated posterior fusion

- recomment addition of anterior fusion for dysplastic scoliosis is therefore recommended

- anterior release then posterior fusion

 

Indications

 

Anterior release and fusion followed by posterior fusion if > 50o

 

Kyphoscoliosis

 

Posterior fusion alone is usually insufficient in patients with kyphosis

 

Decompression of the cord with laminectomy 

- contraindicated because the lesion is usually anterior

- removal of the posterior elements predisposes the patient to further postlaminectomy kyphosis.

- need decompression and fusion

 

> 50o

- brace early

- need anterior and posterior fusion

- may even need brace post surgery

- if have myelopathy symptoms may also need decompression

 

Lordoscoliosis

- in dystrophic