Neurology - neurofibromatosis Flashcards
What is Neurofibromatosis?
Genetic condition that causes nerve tumours (neuromas) to develop throughout the nervous system
These are benign tumours but they do cause neurological and structural problems
What are the types of neurofibramatosis
NF1
NF2
What is the genetic mutation in NF1?
Mutation on chromosome 17 in the NF1 gene
This gene codes for a protein called neurofibromin, which is a tumour suppressor protein.
Inheritance of mutations in this gene is autosomal dominant.
Criteria for diagnosing NF1
2 or more of the following criteria
CRABBING.
C – Café-au-lait spots (6 or more) measuring ≥ 5mm in children or ≥ 15mm in adults
R – Relative with NF1
A – Axillary or inguinal freckles
BB – Bony dysplasia such as Bowing of a long bone or sphenoid wing dysplasia
I – Iris hamartomas (Lisch nodules) (2 or more) are yellow brown spots on the iris
N – Neurofibromas (2 or more) or 1 plexiform neurofibroma
G – Glioma of the optic nerve
Investigations
Diagnosis is based on clinical criteria and no investigations are required to make a definitive diagnosis.
Genetic testing if there is diagnostic doubt
X-rays for bony pain, bony lesions
CT/MRI for investigating lesions in the brain, spinal cord, elsewhere in the body
Management of NF1
No treatment of underlying disease process or to prevent the development of neurofibromas or complications
Management is to control symptoms and monitoring for complications
Complications of NF1
Migraines
Epilepsy
Renal artery stenosis causing hypertension
Learning and behavioural problems (e.g. ADHD)
Scoliosis of the spine
Vision loss (secondary to optic nerve gliomas)
Malignant peripheral nerve sheath tumours
Gastrointestinal stromal tumour (a type of sarcoma)
Brain tumours
Spinal cord tumours with associated neurology (e.g. paraplegia)
Increased risk of cancer (e.g. breast cancer)
Leukaemia
What is the genetic mutation in NF2?
Mutation in the NF2 gene on chromosome 22
Inheritance is autosomal dominant
NF2 gene codes for a protein called merlin - a tumour suppressor protein particularly important in Schwann cells.
What is NF2 gene mutation associated with?
Development of schwannomas especially acoustic neuromas
Bilateral acoustic neuromas - almost certainly indicate NF2
What are symptoms of acoustic neuroma?
Hearing loss
Tinnitus
Balance problems
Hearing loss and tinnitus will be unilateral in unilateral lesions, bilateral in bilateral
Where else can you get schwannomas? Treatment of schwannomas
Schwannomas can also develop in the brain and spinal cord with symptoms based on the location of the lesion.
Surgery can be used to resect tumours although there is a risk or permanent nerve damage.
