Neurosurgery Flashcards
What are 3 signs on examination of an anterior fossa skull base fracture?
- CSF rhinorrhoea
- periorbital ecchymosis
- partial/total loss of smell
- eye movement defects
What are 4 signs of middle cranial fossa skull base (petrous temporal bone) fractures?
- Battle sign (bruising behind ear)
- CSF otorrhoea / pain
- hearing loss
- balance problems
What is the definition of spondylolisthesis?
slippage (usually forward) of a vertebra in relation to the vertebra below it
What are 3 causes of spondylolisthesis?
- congenital anomalies of vertebrae
- damage to ligaments or joints secondary to degeneration
- inflammation or trauma
What finding of fundoscopy is strongly suggestive of subarachnoid haemorrhage?
subhyaloid haemorrhages
How should investigations be performed for suspected subarachnoid haemorrhage?
- CT - CT non contrast first line but angiography if possible - ideally within 6h of sx onset
- if CT negative - MRI or LP - CONSIDER LP IF CTH NEGATIVE AND DONE >6H AFTER SYMPTOM ONSET
- LP must not be performed if raised ICP
What LP findings are expected with SAH if if is performed within 6-12 hours?
CSF uniformly blood stained (should ideally wait for 12 hours until performing LP)
What LP findings are expected with SAH if if is performed between 12hours - 2 weeks of symptom onset?
supernatant is xanthochromic
What is the aim of initial management of SAH?
prevent further bleeding and reduce rate of secondary complications (ischaemia or hydrocephalus)
In what proportion of cases of migraine is the headache bilateral?
30%
What are the 7 NICE criteria for CT head within 1 hour for head injury?
- GCS <13 on initial assessment
- GCS <15 2 hours post injury
- suspected open or depressed skull fracture
- basal skull fracture - haemotympanum, panda eyes, CSF rhinorrhoea/otorrhoea, Battle’s sign
- post-traumatic seizure
- focal neurological deficit
- > 1 episode vomiting
What are 4 NICE criteria for CT head within 8 hours for head injury?
- age >65y
- history of bleeding or clotting disorders including anticoagulants
- dangerous mechanism of injury e.g. pedestrial or cyclist struck by car, occupant ejected from motor vehicle, fall from heigh <1m or 5 stairs
- > 30min retrograde amnesia of events immediately before head injury
Which vessel is classically involved in extradural haematoma?
middle meningeal artery - tear, often following skull fracture
What causes the bleeding in a subdural haematoma?
tearing of the bridging veins between the dura mater and arachnoid mater, leading to bleeding in the subdural space
What 2 groups can primary brain injury be divided into?
- focal: contusion or haematoma
- diffse: diffuse axonal injury
What causes diffuse axonal injury?
mechanical shearing following deceleration, causing disruption and tearing of axons
What are 2 types of contusions (type of primary TBI)?
- coup (adjacent to side of impact)
- contre-coup (contralateral to side of impact)
What is secondary brain injury?
- occurs when cerebral oedema, ischaemia, infection, tonsillar or tenotrial herniation exacerbates the original injury
- normal cerebral auto-regulatory processes are disrupted following trauma rendering the brain more susceptible to blood flow changes and hypoxia
What is the Cushing’s reflex in traumatic brain injury?
hypertension and bradycardia - occurs late an usually pre-terminal event
What type of injury causes extradural haematoma?
acceleration-deceleration trauma or blow to side of head
Which region of the brain do the majority of extradural haematomas occur?
temporal region (skull fractures cause rupture of middle meningeal artery here)
Which regions of the brain does a subdural haematoma most commonly occur?
frontal and parietal lobes
How does the onset of symptoms of subdural vs extradural haemorrhage vary?
slower onset of symptoms with subdural; may be fluctuating confusion/consciousness vs lucid interval in extradural
What are 6 risk factors for an intracerebral haematoma?
- hypertension
- vascular lesion e.g. aneurysm / AVM
- cerebral amyloid angiopathy
- trauma
- brain tumour
- infarct
What is the appearance of extradural and subdural haematoma on CT?
extradural - lentiform, subdural: crescenteric
What is the most common cause of subarachnoid haemorrhage?
head injury - traumatic SAH
What proportion of cases of spontaneous subarachnoid haemorrhage is due to saccular berry aneurysms?
85%
What are 4 diseases associated with berry aneurysms?
- hypertension
- adult polycystic kidney disease
- Ehlers-Danlos syndrome
- coarctation of the aorta
What ECG changes may be seen in subarachnoid haemorrhage?
ST elevation (may be secondary to autonomic neural stimulation from hypothalamus or elevated levels of circulating catecholamines)
What are 3 aspects of management of a confirmed aneurysmal SAH?
- supportive: bed rest, analgesia, VTE prophylaxis, discontinuation of antithrombotics
- oral nimodipine - prevent vasospasm
- coil by interventional neuroradiologists (/ craniotomy + clipping by NSx)
What is the purpose of coil / clipping of subarachnoid haemorrhages that are aneurysmal?
preventing rebleeding
What are 5 complications of subarachnoid haemorrhage?
- rebleeding
- hydrocephalus
- vasospasm - delayed cerebral ischaemia
- hyponatraemia - usually due to SIADH
- seizures
What proportion of cases of SAH rebleed?
10%
When does rebleeding of SAH most commonly occur?
first 12 hours
How is hydrocephalus secondary to SAH treated?
temporarily with an external ventricular drain (CSF diverted into bag at bedside), or long-term ventriculoperitoneal shunt if required
When does vasospasm typically occur as a complication of SAH?
7-14 days after onset
What is the treatment of vasospasm following SAH?
ensure euvolaemia, consider vasopressure if symptoms persist
What are 3 important predictive factors in SAH?
- conscious level on admission
- age
- amount of blood visible on CTH
What distinguishes acute vs subacute vs chronic subdural haemorrhage?
- acute: symptoms develop within 48h of injury, rapid deterioration
- subacute: symptoms days to weeks post-injury, more gradual progression
- chronic: common in elderly - develops over weeks to months
What pattern of consciousness is typical in chronic SDH?
lucid interval followed by gradual decline in consciousness
Why might a unilateral dilated pupil be seen in subdural haematoma?
haematoma compressing third cranial nerve
What is Cushing’s triad?
seen due to increased intracranial pressure - bradycardia, hypertension, respiratory irregularities
What is usually the aetiology of an acute subdural haematoma?
high-impact trauma (often other underlying brain injuries)
What will be seen on CT in subdural haematoma?
crescenteric collection, not limited by suture lines (mass effect may be seen with midline shift / herniation)
What are the management options for acute subdural haematoma?
- small / incidental: observe, conservative
- surgical options: monitoring of ICP, decompressive craniectomy
Which vessels lead to a subdural haematoma?
rupture of small bridging veins within subdural space
What will differ in acute vs chronic subdural haematomas on imaging?
will be dark (hypodense) in chronic rather than bridge (hyperdense)
What are the management options for chronic subdural haematoma?
- incidental / small, no neuro deficit: conservative
- confused / neuro deficit / severe findings: surgical decompression with burr holes
What is the guidance for a patient on warfarin with a head injury with no other indications for CT head?
do CT head within 8 hours of injury
What are 4 features of L3 nerve root compression due to a prolapsed disc?
- sensory loss over anterior thigh
- weak hip flexion, knee extension and hip adduction
- reduced knee reflex
- positive femoral stretch test
What are 4 features of L4 nerve root compression due to a prolapsed disc?
- Sensory loss anterior aspect of knee and medial malleolus
- Weak knee extension and hip adduction
- Reduced knee reflex
- Positive femoral stretch test
What are 4 features of L5 nerve root compression due to a prolapsed disc?
- sensory loss dorsum of foot
- weakness in foot and big toe dorsiflexion
- reflexes intact
- positive sciatic nerve stretch test
What are 4 features of S1 nerve root compression due to a prolapsed disc?
- sensory loss posterolateral aspect of leg and lateral aspect of foot
- weakness in plantar flexion of foot
- reduced ankle reflex
- positive sciatic nerve stretch test
What is the approach to management for sciatica due to prolapsed disc?
- NSAIDS +- PPI
- physisotherapy / exercises
- if symptoms persist after 4-6 weeks - refer for consideration MRI
What are the classic features of lumbar spinal stenosis?
- back pain / neuropathic pain
- claudication like symptoms
- sitting better than standing (relieved leaning forwards/crouching)
- easier to walk uphill rather than downhill
What is the investigation of choice in lumbar spinal stenosis?
MRI
What is the treatment of lumbar spinal stenosis?
laminectomy
What level of metastatic spinal cord compression causes upper motor neuron signs in the legs vs lower motor neuron signs? What other features are seen?
- Above L1: UMN signs in legs, sensory level
- Below L1: LMN signs, perianal numbness
What happens to tendon reflexes in metastatic spinal cord compression?
- increased below level of lesion
- absent at level of lesion
What is the management of metastatic spinal cord compression?
- high-dose oral dexamethasone
- urgent oncological assessment - consideration of radiotherapy or surgery
What should be done if there is life-threatening rising ICP e.g. extradural haematoma whilst theatre is prepared / transfer arranged?
may require use of IV mannitol / furosemide
What may be the required treatment for diffuse cerebral oedema due to head injury?
decompressive craniotomy
What is the only situation where exploratory Burr holes may be required in clinical practice?
little management in modern practice except where scanning may be unavailable and to thus facilitate creation of formal craniotomy flap
What is the management of depressed skull fractures that are open?
formal surgical reduction and debridement
What is the management of closed depressed skull fractures?
may be managed non-operatively if minimal displacement
When should ICP monitoring be performed after traumatic head injury?
- appropriate if GCS 3-8 and normal CT head
- GCS 3-8 and abnormal CT head - mandatory
What is the minimum cerebral perfusion pressure in adults after TBI?
70 mmHg
What is the minimum cerebral target perfusion pressure in children?
between 40 and 70 mmHg
What does a unilaterally dilated pupil indicated after TBI?
3rd nerve compression secondary to tentorial herniation
What do bilaterally dilated pupils after TBI Suggest?
poor CNS perfusion / bilateral 3rd nerve palsy
What are 3 causes of bilaterally constricted pupils?
- opiates
- pontine lesions
- metabolic encephalopathy
What are 3 things that elicit pain in lower back pain due to facet joint pathology?
- pain worse in morning
- pain worse on standing
- worse on extension of back
What is the commonest cause of recurrent symptoms after degenerative cervical myelopathy surgery with cervical laminectomy?
recurrent disease in adjacent spinal levels not treated by initial decompressive surgery (adjacent segment disease) - patients require ongoing follow-up after surgery