9. Neurosurgery Flashcards
What is the best at detecting VAE
Precordial Doppler - best non invasively
Options for VAR detection
Precordial Doppler is the most sensitive non-
invasive monitor, simple and able to detect as little
as 0.015 mL/ kg/ min of intracardiac air.
Precordial stethoscope requires a large amount of air to
be entrained before detection of the classic millwheel murmur. End- tidal CO
2 is not specific to air
embolism.
Transoesophageal monitors are more sensitive than precordial Doppler but are invasive, expensive, and can be associated with complications such as oesophageal injury.
23- year- old man with complete transection of his spinal cord at T1 following an accident five months ago presents for a cystoscopy and urethral dilatation.
He is known to have muscle spasms and has had one
previous episode of autonomic dysreflexia.
His body mass index (BMI) is 38. Which of the following would be the most appropriate anaesthetic technique? A. No anaesthesia is required B. Lumbar epidural C. Low- dose spinal D. General anaesthesia with LMA E. Sedation with midazolam
C. Low- dose spinal
Anaesthetic options in cord transections with ADR
If site of surgery is below the level of the lesion and is complete no anaesthesia may be required
unless the patient suffers from muscle spasms or autonomic dysreflexia (ADR). That is therefore
not appropriate in this case.
Spinal anaesthesia is safe and is an effective way to abolish muscle spasms and ADR.
Epidurals may be unreliable for general or urological procedures.
Sedation does not reliably abolish muscle spasms or
ADR.
A general anaesthetic would be an acceptable technique but intubation would be preferable as this
patient has a high thoracic lesion and would have paralysis of his intercostal and abdominal wall
muscles. He would be prone to hypoventilation and have reduced lung compliance. He would also
be more at risk of aspiration as he has a high BMI and slower gastric emptying
A 24- year-
old man presents to the emergency department following a fall with a head injury.
There are no obvious extracranial injuries.
His Glasgow Coma Scale (GCS) is 6/
15.
You intubate him with manual
in-line stabilization of his cervical spine. What is the most important
management step to prevent secondary injury?
A. Maintain a mean arterial pressure (MAP) >80–
90 mmHg
B. Maintain a PaCO 2 of 4.0– 4.5 kPA
C. Aim for a blood glucose of 6–10 mmol
D. Actively cool the patient to 35°C
E. Maintain a PaO2 >20 kPa
A. Maintain a mean arterial pressure (MAP) >80–
90 mmHg
Secondary brain injury targets
The main targets to avoid secondary brain injury are intubation and ventilation of anyone with a GCS <8. Then aim for PaO 2 >13 kPa,
PaCO2 4.5–5 kPa,
a MAP >80– 90 mmHg,
and normoglycaemia.
Hyperthermia should also be avoided.
The most important of these are blood pressure control and maintaining oxygenation.
Episodes of hypotension or hypoxia are associated with a poorer outcome
- A 26-year-old female presents
with subarachnoid haemorrhage (SAH).
She has no significant past medical history. On your arrival her eyes are open spontaneously,
speech is confused,
and she is localizing to pain
on the right side only.
Pupils are equal and reactive. What is the most
appropriate clinical severity grade attributed?
A. Grade 1
B. Grade 2
C. Grade 3
D. Grade 4
E. Grade 5
C
Grading systems for SAH
There are more than 40 grading systems that can be used to describe the severity of SAH.
A frequently used scale based on clinical signs is the World Federation of Neurosurgeons Scale
(WFNS) and is graded 1–5 based on GCS and motor deficit.
It is related to prognosis.
This patient has a GCS of E4, M5, V4 (total 13/15)
with a hemiparetic motor deficit evident.
Clinically based scales are subject to interprofessional variability on assessment but do provide a
means of summarized communication between team members and the regional neurological centre
Severity of SAH grading
Grade
WFNS description
Severity of SAH grading
Grade
WFNS description
1 GCS 15, no motor deficit
2 GCS 13–14, no motor deficit
3 GCS 13–14 with motor deficit
4 GCS 7–12, with or without motor deficit
5 GCS 3– 6, with or without motor deficit
- You are anaesthetizing a patient who is receiving posterior fossa surgery in the prone position.
Their head is in a three- pin clamp.
There is a sudden cardiovascular collapse proceeding immediately to cardiac arrest. The correct sequence of actions is:
A. Remain prone, clamp remains, commence posterior compressions
B. Remain prone, commence posterior compressions, release head from clamp
C. Remain prone, release head from clamp, commence posterior compressions
D. Release head clamp, leave pins
in situ, turn supine and commence compressions
E. Remove all pins, turn patient supine, commence compressions
B. Remain prone, commence posterior compressions, release head from clamp
CPR in head clamp pins proned
Cardiopulmonary resuscitation (CPR) should not be delayed and there is no immediate need to turn the patient to the supine position;
CPR should be started with the patient in the prone
position.
The head can be released from the clamp on the operating table rather than trying to release the head from the pins.
This reduces the risk of injuring the scalp, leaving a bleeding pin- hole, or the operator being injured by the pins.
The surgeon can support the patient’s head while
CPR is administered
- You are taking a 64-
year-old man with learning difficulties for magnetic
resonance imaging (MRI) of the brain under anaesthesia.
The presence of which of the following would be a contraindication to this procedure?
A. Prosthetic hip replacement
B. Sternotomy wires for previous coronary artery bypass graft (CABG)
C. Cochlear implant
D. Plate in wrist from previous open reduction and internal fixation (ORIF)
E. Metal heart valve
C. Cochlear implant
Absolute contraindications to MRI include
1 cochlear implants,
2 intra- ocular foreign bodies,
3 ferromagnetic neurovascular clips.
Cardiac pacemakers and implantable defibrillators would also be contraindicated as these may malfunction within the 5 Gauss line.
No C/I devices
Most modern prosthesis are non- ferromagnetic. General surgical clips, artificial heart valves, and sternal wires are usually deemed safe as they are fixed in place by fibrous tissue
7.
A 28-year-old man has complete transection of this spinal cord at T4 following a road traffic accident 18 months ago.
He is coming to theatre for insertion of a Baclofen pump.
In theatre reception he complains of
headache and flushing and his blood pressure is
194/ 98 mmHg.
What would be the most appropriate initial step?
A. Re-check blood pressure
B. Perform an ECG
C. Exclude bladder obstruction
D. Give diazepam pre- medication
E. Take blood cultures
C. Exclude bladder obstruction
This is describing autonomic dysreflexia and the most important first step is to exclude urinary
obstruction before administration of drugs
- A 37- year-old woman suffered a SAH four days ago. She is a smoker with no past medical history of note. The aneurysm was secured with coiling.
Her GCS is currently 15 and there is no neurological deficit.
The most common cause of a delayed neurological deficit now
is:
A. Delayed cerebral ischaemia
B. Hydrocephalus
C. Seizure
D. Re- bleeding
E. Cerebral
oedema
A. Delayed cerebral ischaemia
Complications of SAH
Risk Rebleeding highs when
Hydrocephalus
Seizures
Those with poor clinical grade SAH and/ or large amounts of subarachnoid and intraventricular
blood are at particularly high risk of complications.
The risk of re-bleeding is greatest immediately after the initial haemorrhage, with rates of 5–10%
within the first three days.
Twenty to 30% of patients develop hydrocephalus, usually within the first three days but it may also be delayed.
Clinical seizures are uncommon, occurring in only 1–7% of patients. In patients with an unsecured aneurysm, they are often a sign of a re- bleed.
Although seizures should be treated aggressively,
the use of prophylactic anticonvulsants is associated with a worse outcome after SAH and is not recommended.
Delayed cerebral ischaemia occurs in >60% with the greatest risk between days 4 and 10 and
may even occur in the absence of vasospasm.
Smokers are particularly at risk for vasospasm. This
patient is a smoker starting at day 4 post bleed
A 42- year-old man presents for transsphenoidal excision of pituitary adenoma.
He originally presented with refractory hypertension,
diabetes, and central obesity.
The most likely endocrine abnormality is:
A. Hyperprolactinaemia
B. Antidiuretic hormone (ADH) hyposecretion
C. Thyroid stimulating hormone (TSH) hypersecretion
D. Adrenocorticotropic hormone (ACTH) hypersecretion
E. Growth hormone hypersecretion
D. Adrenocorticotropic hormone (ACTH) hypersecretion
Cushings
D/T
Rx for Adenoma
Typical habitus
This patient presents with features of Cushing’s disease.
This is an excess of glucocorticoid due to hypersecretion of ACTH from a pituitary corticotrophin adenoma,
the term Cushing’s syndrome being applied to a non- specific state of chronic glucocorticoid excess regardless of cause.
Surgical excision is the definitive management,
but medical treatment may reverse much of the effects of excess glucocorticoid and considerably reduces perioperative risk.
The typical habitus of Cushing’s syndrome is one of truncal obesity, moon face and thin extremities.
Glucose intolerance is seen in almost two-thirds of patients with Cushing’s disease, half of whom will have frank diabetes
You assess a 46-year-old woman for percutaneous endoscopic gastrostomy (PEG) tube insertion. She has a six-month progressive neurological condition with chorea, dystonia, and pyramidal signs.
She is suspected to have variant Creutzfeldt–
Jakob disease.
The most appropriate advice is:
A. No risk from routine contact, no isolation, disposable airway equipment, disposable
surgical endoscope
B. No risk from routine contact, no isolation, disposable airway equipment, reusable surgical
endoscope
C. Barrier nursing, isolation, disposable airway equipment, disposable surgical endoscope
D. Barrier nursing, isolation, disposable airway equipment, reusable surgical endoscope
E. No risk from routine contact, no isolation, reusable airway equipment, reusable surgical
endoscope
A. No risk from routine contact, no isolation, disposable airway equipment, disposable
surgical endoscope
Prion proteins and removal
Cleaning and destruction
Abnormal prion protein is not completely removed by conventional sterilization methods, including
autoclaving. This poses problems for transmission of prion disease by contaminated surgical
equipment. This is relevant when a patient with CJD, or at increased risk of CJD, has a procedure
involving tissue which is deemed of medium or high
risk.
With the advent of CJD, there has been a need for airway equipment to become single use. In most
centres, disposable laryngoscope blades and single-
use laryngeal masks are now in routine use.
While fibreoptic intubating endoscopes have until recently been sterilized and reused, disposable
endoscopes are now available.
Anaesthetizing a patient with suspected CJD is essentially similar to routine practice with no particular barrier measures, routine contact infection risk, or isolation required.
In this case, the gastrointestinal lymphoid tissue is of medium infectivity risk so the surgical scope should be incinerated
11.
A 72- year- old woman with a one- year history of myasthenia gravis presents for wide local excision of breast cancer. She has no other significant past medical history.
Her medication includes Pyridostigmine 90 mg three times per day.
Preoperative investigation revealed a forced vital capacity (FVC) of 4.2 L, and normal echocardiography and ECG.
She is of average height and normal BMI. She is able to manage one flight of stairs. She has no swallowing problems. There is no ITU bed currently available. What is the best
plan?
A. Postpone surgery until ITU bed availability
B. Proceed with spontaneous breathing technique on laryngeal mask airway (LMA), High
Dependency Unit (HDU) postoperatively
C. Intubate with an opiate based technique avoiding muscle relaxants, HDU postoperatively
D. Give suxamethonium, intubate, HDU postoperatively
E. Give non- depolarizing muscle relaxant, intubate, HDU postoperatively
B. Proceed with spontaneous breathing technique on laryngeal mask airway (LMA), High Dependency Unit (HDU) postoperatively
12. Which of the following operative positions is best avoided in routine posterior fossa neurosurgery? A. Trendelenburg B. Supine C. Prone D. Park bench E. Lateral
A. Trendelenburg
Posterior fossa surgery positions
best avoided
- A
Posterior fossa surgery is commonly performed in supine, prone, sitting, lateral, and park bench
positions.
The Trendelenburg position would lead to increased venous engorgement although may be used in an emergency,
when air embolism is suspected, to place the surgical field below the level of the heart.
Park bench position is a modification of the lateral position where the patient is positioned semi-prone with the head flexed and facing the
floor. This facilitates greater access to
midline structures and, in selected patients, avoids the need for the prone position
