Neurology

Question 1

Brain metastases epidemiology

Answer 1

• 55% malignant
• 3% of all cancers - 9th most common
• Common differential diagnosis
• In adults - majority supratentorial
• In children - majority in posterior fossa

Question 2

Brain metastases types

Answer 2

• Over 150 types
• Primary:
  
  • Meningioma - tumour of brain lining
  • Paediatric - germ cells, sellar region
  • Gliomas - tumours of intrinsic brain
  • Carnal nerve tumours e.g. acoustic neuroma
  • Lymph cell tumours - primary CNS
• Secondary:
  
  • Matastatic tumours from lung, breast, colorectal, testicular, renal cell, malignant melanoma

Question 3

Brain metastases classification

Answer 3

• WHO classification - histology
• 1 - neuroepithelial tumours (most common)
  
  • Astrocytic - most common
  • Oligodendroglial - IDH-1 mutation positive
  • Ependymal - line the ventricles and spinal cord
  • Neuronal and neuro-glial
  • Pinela
  • Embryonal
  • Choroid Plexus
• 2
  
  • Cranial and spinal nerve tumours
  • Meningeal tumours - second most common
  • Lymphomas - without evidence of systemic disease
  • Germ cell tumours - within brain
  • Metastatic tumours

Question 4

Brain metastases WHO grading

Answer 4

• WHO grading I-IV
  
  • I - Pilocytic astrocytoma, good prognosis, completely benign, mainly in children
  • II - Diffuse astrocytoma, >5yr prognosis, premalignant tumour
  • III - Anaplastic astrocytoma, 2-5yr prognosis, malignant, will see active growth and mitotic activity on microscope
  • IV - Glioblastoma Multiforme (GBM), <1yr prognosis, will show active growth, mitotic activity, necrosis and vascular proliferation

Question 5

Brain metastases causes

Answer 5

• Majority no cause
• Ionising radiation
• 5% family history
• Immunosuppression

Question 6

Brain metastases symptoms

Answer 6

• Cancer symptoms - weigth loss, malaise, loss of appetite
• Raised ICP headache - worse in morning or lying down
• Seizures - happens in 80%, type depends on where tumour is
• Focal neurological symptoms - progressive over days to weeks, depends on region of tumour
• Papilloedema - swelling of optic disc from venous obstruction from raised ICP

Question 7

Brain metastases differential diagnosis

Answer 7

• Aneurysm
• Abscess
• Cyst
• Haemorrhage
• Idiopathic Intracranial Hypertension

Question 8

Brain metastases investigations

Answer 8

• MRI - will show high grade tumours, irregular mass with vasogenic oedema
• Biopsy - using frame-based/frameless stereotactic
• Low grade gliomas - look at cerebral blood volume, MR spectroscopy (composition), rate of growth, bloods, molecular markers (IDH mutation, ATRX loss, TP53 mutation)

Question 9

Brain metastases treatment

Answer 9

• High grade - dexamethasone (reduce oedema), biopsy or resection, radiotherpat, chemotherapy (temozolamide, PCV)
• Low grrade - resection or biopsy, radiotherapy alone (delays progression), radio and chemo (improves survival)

Question 10

Cauda Equina epidemiology

Answer 10

• Rare
• Occurs in 2% of herniated discs
• Can occur at any age

Question 11

Cauda Equina pathology

Answer 11

• Nerve root compression caudal (distal) to the termination of the spinal cord at L1/L2
• Usually large central disc herniation at L4/L5 or L5/S1 levels (sciatica)
• Generally, S1-S5 nerve root compression – important in bladder function

Question 12

Cauda Equina causes

Answer 12

• Herniation of lumbar disc - mostly L4/L5 and L5/S1
• Spondylolisthesis - slippage of one vertebra over the one below so effects root below
• Trauma
• Tumour
• Infection
• Post-op haematoma

Question 13

Cauda Equina Symptoms

Answer 13

• Saddle anaesthesia (perineum, perianal, medial legs and thigh)
• Less bladder and bowel control - increased tone of anal sphincter and bladder muscle wall, urinary retention
• Erectil dysfunction
• Lumbosacral pain
• Lew weakness - flaccid and areflexic (absence of deep tendon reflexes)
• Paraplegia

Question 14

Cauda Equina differential diagnosis

Answer 14

• Conus medullaris syndrome
• Vertebral fracture
• Peripheral neuropathy
• Mechanical back pain

Question 15

Cauda equina investigations

Answer 15

• MRI spine
• Exam:
  
  • Knee flexion - tests L5-S1
  • Ankle plantar flexion - S1-S2
  • Straight leg raising - L5-S1
  • Femoral stretch test - L4

Question 16

Cauda Equina management

Answer 16

• Refer to neurosurgeon asap
• Surgical decompression
• High dose dexamethasone
• Corticosteroids

Question 17

Cauda Equina red flags

Answer 17

• Bilateral sciatica - pain, weakness, numbness, tingling
• Bilateral flaccid leg weakness
• Saddle anaesthesia
• Bladder and bowel dysfunction
• Erectile dysfunction
• Areflexia