Astrocytomas are associated with all of the following syndromes, except
neurofibromatosis type 2
The exception is neurofibromatosis type 2 (NF2). NF2 results from mutation of the NF2 (merlin/schwannomin) gene on chromosome 22q12 and is characterised by bilateral vestibular schwannomas, along with meningiomas, other cranial and spinal schwannomas, ependymomas and juvenile posterior subcapsular cataract. Astrocytic tumours are not part of its classical spectrum.
The other three are genuinely astrocytoma-associated. Neurofibromatosis type 1 (neurofibromin, chromosome 17q11) classically causes optic pathway gliomas and brainstem pilocytic astrocytomas, with cafe-au-lait macules, Lisch nodules, axillary freckling and neurofibromas. Li-Fraumeni syndrome (germline TP53) predisposes to astrocytoma and glioblastoma besides sarcoma, breast and adrenocortical carcinoma. Cowden disease (germline PTEN) features the cerebellar dysplastic gangliocytoma of Lhermitte-Duclos disease with trichilemmomas and thyroid and breast tumours.
Key point: NF1 gives optic nerve gliomas; NF2 gives bilateral vestibular schwannomas and meningiomas - a favourite one-line discriminator.
Important Questions from Brain & Nervous System Surgery
Which of the following chromosomal abnormalities are associated with brain tumours?
1. Neurofibromatosis type 1
2. Neurofibromatosis type 2
3. Peutz-Jeghers syndrome
4. Hereditary nonpolyposis colorectal cancer
Select the correct answer using the code given below.
Consider the following clinical features:
1. Raised ICP
2. Seizures
3. Focal deficit
4. Headache
Which of the above clinical features are related to most brain tumours?
- The most common type of brain tumours associated with neurofibromatosis type 1 brain tumour syndrome is
Upper motor neuron lesions are characterized by which of the following?
1. Increased tone spasticity
2. Hyperreflexia
3. Absent plantar response
4. Motor weakness
Select the correct answer using the code given below.
A comatose patient after sustaining severe head injury has been admitted in neurosurgical ICU. Which of the following parameters should ideally be maintained in this patient ?
1. $pCO_2 = 4.5 – 5.0$ kPa ($33-38$ mm Hg)
2. MAP = $80 – 90$ mm of Hg
3. $pO_2 > 11$ kPa ($> 80$ mm Hg)
4. $Na^+ < 130$ meq/L
Select the correct answer using the code given below :
