The subject of Neuro-oncology is a sub-speciality of Neurosurgery and it is impossible to cover even an 1/10th of the knowledge.
In general brain tumours can be defined as intra-axial if coming from the subtance of the brain parenchyma (within forebrain and cerebellum). Those tumours that originate from outside the brain parenchyma are known as extra-axial tumours.
The most common intra-axial tumour is metastasis from either from the lung in males and breast in females.
Other tumours that can spread to the brain include renal cell carcinoma, melanoma, prostate, and testicular. I distinctly remember seeing a sad case in AE for a 23 year old gentleman who presented with a twisting like headache and left handed weakness. Not once did I think he would have multiple metastasis secondary to a melanoma
CT CHEST ABDOMEN PELVIS
Note that normally for patients with mutliple metastasis are not usually treated with surgically unless it is superficial. If no primary can be found a stereotactic biopsy can be performed to try and find a lesion.
Glial tumours or glioma’s are divided into 4 grades based upon histological diagnosis. The most common GBM (Glioblastoma Multiforme) is associated with poor prognosis and is a grade 4 glioma.
Remember from your early days at medical school tumours are graded in accordance to histological diagnosis:
- nuclear polymorphism
Neovascularity is secondary to a process called angiogenesis (development of new blood vessels) and when necrosis occurrs due to rapid growth of the tumour necrosis occurrs. It is this necrosis that is hallmark features of a GBM.
70% of patients with GBM’s are dead within 9 months.
The decision to offer patients depends on their Performance Status, Co-Morbidites and obviously patient choice. All patients get a single dose of radiotherapy post operatively, followed by chemotherapy. Despite de-bulking rapid re-growth of the tumour occurrs and these patients often need re-surgery + chemotherapy. Temozolamide chemotherapy is often used in the management of GBM. Gliadel wafers have been used as an intra-operative chemotherapeutic agent, however there has been concerns regarding post operative intra-cranial infection.
This is a T1 weighted axial MRI reveals of an irregular hyperintense lesion in the frontal lobe. This may be indicative of a GBM.
These tumours are slow growing tumours, with a pre-domination for frontal lobe. These tumours are hyperintense on CT scan. They are more benign than GBM’s
Non-Hodgkin’s B Cell Lymphoma
These patients may present on a background of lymphoma or as a new presentation. I saw a lady in acute medicine who had a background history of lymphoma and presented with signifcant reduced mobility and weakness. CT demonstrated hyperintensity within the peri-ventricular region that could be consistent with Lymphoma. Note if you are asked by a consultant which tumours should you not give steroids on the inital presentation, it is a lymphoma. They are often called ghost tumours because if you give steroids they can disappear and you can’t biopsy the lesion. This tumour also has an as association with HIV and AIDS.
Posterior Fossa Masses in Adults
The three differential diagnosis for post fossa masses are:
- Metastasis (common)
Haemangioblastoma’s are benign tumours and occassions are part of the Von-Hippel Lindau Syndrome
We will cover more of this later as there are some interesting cases in general, CSF is produced by choroid plexus cells, epedendymal cells.
Choroid Plexus- choroid plexus carcinoma’s and papilloma’s
Ependymoma’s or from the lining sub-ependymal giant cell astrocytoma’s.
The purpose of including this as a medical student is purely for understandind the cells that produce CSF.
This is a tumour arising from the dura. What is important is that tumours are extremely vascular and blood loss can be quite significant. Often a homogenous mass with a dural tail.
Grade 1: Benign
Grade 11: Atypical
Grade 111: Anaplastic
MRI scan revealing a fronto-parietal meningioma. The proximity of the motor strip should be notified in this case and this patient would have presented with weakness and headaches.
For patients it can be reassuring to tell them that 90% of meningioma’s are benign however on rarer circumstances you can have atypical meningioma’s. The most common site for a meningioma is often at the skull base with a sphenoid wing meningioma, perfectly positioned next to the Carotid Artery and Optic Nerve. Due to the potential for significant blood loss some patients may undergo pre-operative embolisation for the tumour.
Pituitary mass has already been discussed about.
Note these patients often present with unilateral sensineural hearing loss, unexplained tinnitus or a facial nerve palsy.
Typically there are four causes of CPA angle tumours
- Vestibular Schwannoma
- Epidermoid Tumour
The vestibular schwannoma’s are associated with Neurofibromatosis 1 and Neurofibromatosis type 11.
The clinical features of NFM type 1:
Neurofibroma’s and Dermatofibromas
Cafe Au Lait Patches
Optic Nerve Glioma
Bilateral Acoustic Neuroma’s are pathopgnomic of Neurofibromatosis type 11.
Patients with Neurofibromatosis commonly like to attend Medical School OSCE’s and its not just one of them they bring their own family! Certainly at Leicester Medical School they are quite common in attending exams!
Smaller Lesions <3cm in diameter are amenable to radiosurgery
Larger Lesions: can undergo retro-sigmoid craniotomy or trans-labrynth surgery.
Post Op Complications– post op hydrocephalus, facial nerve palsies, and CSF Leakage. Intra-Operative facial nerve monitoring can help reduce the incidence of facial nerve palsy.
Facial Nerve palsy can be measured using the House-Brackman scale. More information can be found on the internet. As mentioned earlier in the anatomy of the facial nerve please remeber the following:
- Artificial tears
- Keep the eye closed at night with a tape
- Surgical options: lateral tarssoraphy
- Gold weight attached to the upper eyelid to help facilitate closure
General Management of Brain Tumours
- CT/MRI Brain (with contrast)
- CT CAP
- PSA, S100, CXR, CEA
- Neuro-oncology MDT
- Dexamethasone + PPI (if cerebral oedema)
- Seizure Management if Required