Surgical Approaches

History  Conceived Walter Dandy  George J Heuer ?

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Popularised by Mahmut G Yasargil

Pterional?  Based around the pterion  Area where the frontal bone, parietal bone, squamous part of temporal bone and the greater sphenoid wing adjoin one another  Overlie the anterior branch of the middle meningeal artery

Indications 2. Most anterior circulation aneurysms except pericallosal 3. Some posterior circulation aneurysm: basilar apex & superior cerebellar artery 4. Suprasellar tumours 5. Sphenoid wing tumours 6. Some frontal tumours

Anaesthesia  Hyperventilation PCO2 = 32 kPa  Arterial line  Decadron IV 10 mg  Prophylactic antibiotics 30 min prior to incision  Mannitol 0.5-1g/kg at time of skin incision  Phenytoin loading dose or maintenance

Positioning  Supine position in Mayfield head holder  Pins? Single/double? Hairline  Rotated 100-600 depending on surgery  Head above heart

Positioning  Gentle flexion of neck  Extension

of head to bring malar eminence superior to the brow  Variable extension: less for paraclinoidal aneurysms and more for distal basilar aneurysms

Minimal shave  Disposable razor  3 cm strip along anterior border of hair line – widow’s peak to sideburn Or  1 cm strip behind hair line: better cosmesis – short term 

Sterile scrub and drape  Betadine/hibitane detergent scrub with sterile gloves – 5 minutes  Alcohol to remove detergent  Dry – sterile towel  Incision marked  Infiltrate? Can be done now or after draping prior to incision  Drape can be stitched or stapled to scalp

Scalp incision  Frontotemporal From midline at anterior edge of hairline to inferiorly to within 1 cm of the superior aspect of zygoma and 1 cm anterior to EAM

Scalp incision  Bicoronal(Souttar) incision for receding hairline  Avoid injury to the anterior division of the superficial temporal artery – blunt dissection with gauze swab  Incision made stepwise with haemostasis using Raney clips or Dandy forceps as the incision progresses to minimise bleeding

Muscle dissection Two methods: 3. Muscle and fascia Incised and dissected off with the galeal flap, the Bovie can be used to make initial cut then the muscle is elevated off the bone with a periosteal elevator to minimise temporal muscle wasting

Muscle dissection 2. The scalp flap is incised and reflected separately, the muscle is dissected along the temporalis fascial plane until the subgaleal fat pad is identified, the fascia is then incised and reflected anteriorly to avoid damage to the frontalis zygomatic branches of the facial nerve

Muscle dissection The flaps are secured anteriorly using small towel clips or fish hooks with rubber bands or springs over a rolled up gauze swab to avoid kinking of the blood vessels Mollison’s and Weitlander retractors can also be used Method 1 is quicker and easier Method 2 provides a lower trajectory for better visualisation

Muscle dissection Complete when the following exposed are: 1 the keyhole 2 the root of the zygoma 3 the supraorbital notch

Burr Holes & Craniotomy 

Single or multiple burr holes

Single: Large burr hole in temporal squamosa High speed drill with footplate to turn craniotomy Avoid frontal sinus – correlate with CT scan Stop with first sign of resistance in region of keyhole Remainder is scored with a burr The flap is the elevated carefully, stripping the dura on the undersurface as the flap is elevated The flap is fractured by hinging it along the scored wing Alternatively a second burr hole can be placed at the keyhole Middle meningeal artery cauterised and divided and sphenoid wing waxed

Burr Holes & Craniotomy Multiple burr holes Required if using Gigli saw 3 to 5 burr holes can be made The dura stripped with Gigli guide(invented by De Martel in 1908)

Removal of the Sphenoid Wing  Leksell Rongeur is used to remove the remaining squamosa  The dura is dissected of the sphenoid wing using Penfield dissector/Gigli guide/McDonald  The sphenoid wing is then drilled or nibbled with a rongeur to the orbitomenningeal artery

Dural Opening Surgicel strips are inserted between the dura and the bone Tent sutures Dura opened in curvilinear manner across the sylvian fissure with dura hook and a 15 blade or an 11 blade turned up The opening is completed using Metzenbaum scissors over a wet cottonoid patty The flap is reflected over the muscle and secured with a 4/0 suture separate from the muscle Patties all around and dark towel to reduce microscope glare

 Gelfoam

/spongistan are placed at the dural margins to avoid subdural extension of intraoperative bleeding  Tefla for cortical protection

READY TO START

Closure  

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Dura close 4/0 suture: interrupted or continuous Unable to close? – pericranium graft or rather leave large holes with underlay of graft or compressed gelfoam or bicol to avoid one-way valve effect Surgicel blanket if oozy Tent sutures tightened Bone flap secured Muscle approximated Suction drainage under muscle Scalp closed with interrupted or continuous sutures Clips to skip Dressings TBCo Or crepe bandage head gear Remove clips in 5 days

Complications Intraoperative 1. breach of frontal sinus may result in CSF leak Remedy : exenteration of sinus and cover with vascularised pericranium 2. Entry into orbit may cause post op eye swelling Remedy: wax  Postoperative  Subgaleal collection Porto-vac Tap and wrap - sometimes steroid taper  TMJ Syndrome Soft diet and NSAID  Wound infection Superficial – antibiotics Deep open debridement 

 Indications

Lesions of the frontal lobe 3. CSF fistula repair 4. Olfactory groove tumours 5. Sellar-area tumours 2.

Anaesthesia  hyperventilation PCO2 = 32 kPa  Arterial line  Decadron IV 10 mg  Prophylactic antibiotics 30 min prior to incision  Mannitol 0.5-1g/kg at time of skin incision  Phenytoin loading dose or maintenance

Positioning Supine  Head and trunk elevated 200  Neutral  or  turned 200-400 to contralateral side  Neck flexed slightly  Head extended or flexed: Flexed 150 and rotated 150 to contralateral side for optic nerve and orbital roof exposure. 

Minimal shave  3 cm strip along incision  Prep as for std approach  Ear plugs

Incision  Ear to Ear ( truebicoronal )  Ear to superior temporal line of contralateral side( Modified Bicoronal)  Same precaution as for Pterional craniotomy: 1cm anterior to tragus and 1 cm superior to zygomatic arch  Frontal branch of superficial temporal artery

Incision  Incision with knife  Fascia cut with scissors or Bovie  Muscle elevated with Bovie or periosteal elevator  Periosteum elevated with periosteal elevator to preserve a large vascularised pericranial flap  Galea, skin and pericranium reflected anteriorly over roll and secured with towel clips or fish hooks

 Supraorbital

nerve  Supratrochlear nerve  Notch or foramen  Drill bone to preserve nerves

Burr Holes •Unilateral •Burr hole 1 cm lateral to superior sagittal sinus

Burr holes  If exposure of the sinus is required the burr holes can be drilled directly over the sinus

Holes over sinus

Burr Holes  Bilateral approach  Burr holes drilled over the squama first then two directly over sinus or 4 burr holes 1 cm on either side of the superior sagittal sinus

 Underlying

dura stripped using Gigli guide

Craniotomy  Craniotome or Gigli saw  Avoid injury to venous sinus  Frontal sinus almost inevitably opened  Exenterate or obliterate sinus and repair with pericranium at the end of surgery

Dural Opening  Tent sutures  Surgicel  U-shaped flap or cruciate opening  Double ligation of venous sinus at its origin at the frontal base before separation  Separation of falx cerebri

 Patties  Dark

towels  Retractors  Ready To GO

Closure  Repair sinus breach  Vascularised pericranial flap  Watertight closure  Tighten tent sutures  Surgicel blanket  Bone flap secured appropriately; wire/ethibond/plates/craniofi x etc  Suction drain

Complications  Injury to Supratrochlear and supraorbital nerve  Injury to Superior Sagittal Sinus with craniotomy instrument: Small - Pack with Surgicel or gelfoam Large – Ligate if anterior 1/3 of sinus  Inadequate haemostasis of bridging veins  Injury to cerebral arteries in the midline  Subdural/extradural haematomas  Frontal sinus entry: repair as described  Seizures  Sepsis- use separate instrument to isolate and cranialise frontal sinus  CSF leak

History Dandy Indications  Tumours of the third ventricle  Lesions of the lateral ventricle  Corpus callosotomy  Large tumours of the pineal

Anaesthesia  Hyperventilation PCO2 = 32 kPa(25-30)  Arterial line  Decadron IV 10 mg  Prophylactic antibiotics 30 min prior to incision  Mannitol 0.5-1g/kg at time of skin incision  Phenytoin loading dose or maintenance

Positioning  Supine  Head and trunk elevated 200  Neutral/straight  Neck flexed slightly  Head extended 100

Minimal shave  3 cm strip along planned incision  Always on the right side  Disposable razor Incision  Based around coronal suture  L shaped/bicoronal/U-flap  Need to expose 6 cm anterior and 3cm posterior to coronal suture  Flapped / retraction with fish hooks or towel clips  Raney clips or Dandy’s and artery forceps for haemostasis

Burr holes & Craniotomy  To cross midline or not – Controversial  Crossing midline may cause injury and compression of superior sagittal sinus resulting in venous infarction  Burr holes as shown  Bone flap centered 2/3anterior and 1/3 posterior to coronal suture  No more than 2 cm posterior to coronal suture  Laterally4 to 5 cm  Medial bone edge nibbled to edge of sinus

Dural opening  Tent sutures and surgicel for haemostasis  Durotomy u shaped based on superior sagittal sinus  Use microscope and microdissection to preserve pial integrity and avoid injury to cortical vein and granulations  Extend of dural opening only to 2 cm from midline – minimise damage to cortex during retraction  Cortical veins may limit dural opening posterior to coronal suture  3-4 cm of frontal cortical exposure is sufficient  Routine field preparation – patties dark towel and gelfoam

Interhemispheric dissection  Sharp dissection of the interhemispheric fissure  Separation of arachnoid adhesion with bipolar between the hemisphere and the superior sagittal sinus  Small bridging veins may be sacrificed if anterior to the coronal suture, larger ones much be preserve  Careful dissection can mobilise another 3-5 mm

Interhemispheric dissection  The dissection is continued along the falx inferiorly  CSF may be tapped from the right frontal horn  The pericallosal and callosal marginal arteries are identified  The pericallosal arteries are either separated or moved to one side together  The corpus callosum is identified by its pearly white colour

 The

corpus callosum is then incised  1.5-2.5 cm  Deepened with suction and bipolar  1 cm wide

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Ependyma identified CSF drained slowly especially in patient with hydrocephalus to minimise the risk if subdural bleed Then identify the ventricle – right or left by locating the choroid plexus Left ventricle entry- further lateral resection of corpus callosum or fenestrate the septum Not visible-frontal horn –change angle of microscope to a more posterior position

 Choroid

plexus followed to foramen of Monro

Entry into third ventricle  Through Foramen of Monro if dilated  Incise fornix at superior margin of FoM -1

Entry into third ventricle  Transforniceal - incision along the body of the fornix in the midline – 2  Interforniceal – the interforniceal raphe is identified by division of the septal leaves of coagulating the septum down to the fornix  Max 2 cm posterior to FoM – hippocampal commissure

Entry into third ventricle  Transchoroidal – incision of tela fornicis – 3( rather than tela choroida, the latter is more vascular)

 Internal

cerebral veins in the roof of the third must be preserved  Ready to GO

Closure  Cavity filled with warm saline  Haemostasis with bipolar – no surgicel  EVD if needed  Water tight dural closure  Surgicel blanket  Bone flap secured  Std closure

Complications  Injury to superior sagittal sinus – repair it or tie it  Inadvertent Sacrifice of major bridging veins causing venous infarction  Sagittal sinus thrombosis from excessive retraction  Injury t anterior cerebral arteries in the midline  Excessive retraction of bilateral cingulate gyri causing mutism  Excessive opening of forniceal raphe causing memory deficits  IVH  Excessive opening of corpus callosum posteriorly causing disconnection syndrome  Seizures due to frontal lobe retraction damage or venous infarct  Sepsis  Hydrocephalus  CSF leak

READY TO GO PARTY