Surgery: NeuroSurgery Flashcards
Criteria for Brain Stem Death
- Deep Coma: Patient in a deep coma with a known cause.
- Reversible Causes Excluded: Rule out reversible causes.
- No Sedation: Patient should not be under sedation.
- Normal Electrolytes: Confirm normal electrolyte levels.
Testing for Brain Death
Fixed Pupils: Pupils don’t respond to light changes.
No Corneal Reflex: Absence of corneal reflex.
Absent Oculo-Vestibular Reflexes: No eye movements after injecting ice-cold water into each ear.
No Response to Supraorbital Pressure: Lack of response to pressure.
No Cough Reflex: No cough reflex to bronchial stimulation.
Absence of Gagging Response: No gagging response to pharyngeal stimulation.
No Observed Respiratory Effort: No respiratory effort upon ventilator disconnection for at least 5 minutes.
Conditions: Arterial partial pressure of carbon dioxide elevated to at least 6.0 kPa (6.5 kPa in chronic CO2 retention).
Precautions: Adequate oxygenation to avoid anoxic drive stimulus.
Testing procedure for brain death
Conducted by two experienced doctors on separate occasions.
Both doctors must have at least 5 years of post-graduate experience.
One doctor must be a consultant.
Neither doctor can be a member of the transplant team if organ donation is considered.
What is brain herniation
Definition: Herniation results from elevated intracranial pressure, forcefully displacing normal brain structures.
Consequences and urgency of brain herniation
Consequences:
Decompensation of normal brain anatomy.
Compression of vital structures, especially the brain stem.
Urgency:
Neurosurgical emergency requiring immediate intervention.
Interventions may include osmotherapy (hypertonic saline or mannitol) or surgical decompression.
Types of Herniation
Subfalcine: Cingulate gyrus under the falx cerebri.
Central: Downward brain displacement.
**Transtentorial/Uncal: **Uncus displacement under the tentorium cerebelli.
Consequences: Ipsilateral fixed, dilated pupil; contralateral paralysis.
Tonsillar (Coning): Cerebellar tonsils through the foramen magnum.
ICP Impact: Compression of cardiorespiratory center.
Chiari 1 Malformation: Tonsillar herniation without raised ICP.
Transcalvarial Herniation
Definition: Brain displacement through a skull defect (e.g., fracture or craniotomy site).
Clinical Significance: Represents a distinct type of herniation.
Coning
Flashcard: Coning
- ICP Accommodation:
- Cranial vault is confined.
- Initial ICP rises accommodated by CSF shifts.
-
Brisk ICP Rise:
- Once CSF capacity exhausted, ICP rises rapidly.
-
Autoregulation and Circulation Changes:
- Brain autoregulates blood supply.
- Rising ICP prompts systemic circulation changes, often hypertension.
-
Severe Consequences:
- Brain compression, nerve palsies, and brain stem compression.
- Cardiac center involvement leads to bradycardia.
General approach to head injury management
General Approach:
Manage according to ATLS principles.
Address extracranial injuries alongside cranial trauma.
Inadequate cardiac output compromises CNS perfusion.
Types of traumatic brain injury
Extradural Hematoma:
Bleeding between dura mater and skull.
Features: Raised ICP, possible lucid interval.
Subdural Hematoma:
Bleeding into outermost meningeal layer.
Risk factors: Old age, alcoholism.
Subarachnoid Hemorrhage:
Often spontaneous or associated with traumatic brain injury.
Pathophysiology of Brain Injury
Primary Injury:
Focal (contusion/haematoma) or diffuse (axonal injury).
Secondary Injury:
Cerebral edema, ischemia, herniation.
Cushing’s Reflex (Late):
Hypertension and bradycardia
Management of brain injury
Extradural Hematoma:
IV mannitol/frusemide for life-threatening rising ICP.
Diffuse Cerebral Edema:
Decompressive craniotomy.
Skull Fractures:
Surgical reduction for open fractures; nonoperative for closed with minimal displacement.
ICP Monitoring:
GCS 3-8 with abnormal CT.
Cerebral Perfusion Pressure (CPP):
Maintain minimum: 70mmHg in adults, 40-70 mmHg in children.
Pupillary findings on brain injury
Unilaterally Dilated:
Tentorial herniation.
Bilaterally Dilated:
Poor CNS perfusion or 3rd nerve palsy.
Unilaterally Dilated or Equal:
Cross-reactive (Marcus-Gunn): Optic nerve injury.
Bilaterally Constricted:
Opiates, pontine lesions, metabolic encephalopathy.
Unilaterally Constricted:
Sympathetic pathway disruption.
CT Head Within 1 Hour - Indications
GCS < 13 on initial assessment.
GCS < 15 at 2 hours post-injury.
Suspected open or depressed skull fracture.
Signs of basal skull fracture (e.g., haemotympanum, ‘panda’ eyes, CSF leakage, Battle’s sign).
Post-traumatic seizure.
Focal neurological deficit.
More than 1 episode of vomiting.
CT Head Within 8 Hours - Risk Factors
Age 65 years or older.
History of bleeding or clotting disorders, including anticoagulants.
Dangerous mechanism of injury (e.g., pedestrian/cyclist struck by a vehicle, occupant ejected from a vehicle, fall from a height >1 meter or 5 stairs).
More than 30 minutes’ retrograde amnesia after the head injury.
Special Consideration for Warfarin Patients
Perform CT head scan within 8 hours for head injury, even with no other indications.
Types of Traumatic Brain Injury - Basics
Primary Brain Injury:
Focal (contusion/haematoma) or diffuse (diffuse axonal injury).
Diffuse axonal injury results from mechanical shearing, causing axonal disruption and tearing.
Intracranial Hematomas and Contusions:
Extradural, subdural, or intracerebral hematomas.
Contusions may be adjacent (coup) or contralateral (contre-coup) to the impact side.
Secondary Brain Injury:
Occurs due to cerebral edema, ischemia, infection, herniation.
Disrupted cerebral auto-regulatory processes increase susceptibility to blood flow changes and hypoxia.
Cushing’s Reflex:
Late occurrence, usually pre-terminal event.
Manifests as hypertension and bradycardia.
Types of Traumatic Brain Injury - Specific Injuries
Extradural (Epidural) Hematoma:
Bleeding between dura mater and skull.
Often from acceleration-deceleration trauma or side head blow.
Features: Raised intracranial pressure, possible lucid interval.
Subdural Hematoma:
Bleeding into outermost meningeal layer.
Risk factors: Old age, alcoholism, anticoagulation.
Slower onset than epidural hematoma; fluctuating confusion/consciousness.
Subarachnoid Hemorrhage:
Sudden occipital headache.
Spontaneous or associated with traumatic brain injury.
Types of Traumatic Brain Injury - Intracerebral Hematoma
Intracerebral Hematoma:
Collection of blood within brain substance.
Causes/risk factors: Hypertension, vascular lesions, trauma, tumors, infarcts.
Presentation similar to ischemic stroke or decreased consciousness.
CT imaging shows hyperdensity.
Treatment: Conservative under stroke physicians; surgical evacuation for large clots in impaired consciousness.
Hydrocephalus Overview
Definition:
Excessive cerebrospinal fluid (CSF) volume in the brain ventricular system.
Caused by an imbalance between CSF production and absorption.
Presentation:
Symptoms due to raised intracranial pressure.
Headache (worse in the morning, lying down, during Valsalva).
Nausea, vomiting, papilloedema, coma (severe cases).
Hydrocephalus in Infants
Infant Presentation:
Skull sutures not fused; rise in pressure increases head circumference.
Bulging, tense anterior fontanelle.
Failure of upward gaze (‘sunsetting’ eyes) in severe cases.
Categories:
Obstructive (non-communicating) hydrocephalus.
Non-obstructive (communicating) hydrocephalus.
Obstructive vs. Non-Obstructive Hydrocephalus
Obstructive Hydrocephalus:
Structural pathology blocks CSF flow.
Ventricular dilatation seen superior to the obstruction.
Causes: Tumors, acute hemorrhage, developmental abnormalities.
Non-Obstructive Hydrocephalus:
Imbalance in CSF production/absorption.
Causes: Increased CSF production or reabsorption failure.
Includes normal pressure hydrocephalus with dementia, incontinence, disturbed gait.
Investigation and Treatment of hydroc
Investigation:
CT head as first-line imaging.
MRI for detailed investigation, especially for suspected underlying lesions.
Lumbar puncture for diagnosis and therapeutic drainage in some cases.
Treatment:
External ventricular drain (EVD) for acute, severe hydrocephalus.
Ventriculoperitoneal shunt (VPS) for long-term CSF diversion.
Surgical treatment for obstructive hydrocephalus.
Note:
Caution with Lumbar Puncture:
Must not be used in obstructive hydrocephalus.
Induced pressure difference may cause brain herniation.
Subarachnoid Hemorrhage (SAH) Overview
Definition:
Intracranial hemorrhage in the subarachnoid space, deep to the meninges.
Distinguished into traumatic SAH (head injury) and spontaneous SAH (non-traumatic).
Spontaneous SAH Causes:
Intracranial aneurysm (85% of cases).
Conditions associated with aneurysms: Hypertension, polycystic kidney disease, Ehlers-Danlos syndrome, coarctation of the aorta.
Arteriovenous malformation, pituitary apoplexy, mycotic aneurysms.
Clinical Presentation and Investigation
SAh
Presenting Features:
Sudden-onset severe headache (‘thunderclap’).
Occipital pain peaking within 1 to 5 minutes.
Nausea, vomiting, meningism, coma, seizures, ECG changes.
Investigation:
Non-contrast CT head is the first-line.
CT shows blood in basal cisterns, sulci, and ventricular system.
Lumbar puncture if CT done >6 hours after onset, showing normal results.
Management of Aneurysmal SAH
Supportive Measures:
Bed rest, analgesia, thromboembolism prophylaxis.
Discontinue antithrombotics, if present.
Oral nimodipine to prevent vasospasm.
Prompt Intervention for Aneurysms:
Most aneurysms treated with coil by interventional neuroradiologists.
Some require craniotomy and clipping by a neurosurgeon.
Complications and Predictive Factors SAh
Complications:
Re-bleeding (10% cases, high mortality).
Hydrocephalus (temporary external ventricular drain or long-term shunt).
Vasospasm (delayed cerebral ischemia, 7-14 days post-onset).
Hyponatremia (e.g., SIADH), seizures.
Predictive Factors:
Conscious level on admission.
Age.
Amount of visible blood on CT head.
