A craniotomy involves opening the skull, performing the indicated operation and closing the skull (by securing the bone into its original position). Want to see one? Click here. [This is not for the faint-hearted.]
There are many indications for a craniotomy: evacuation of blood on the surface of the brain (subdural hematoma, for example), resection of a brain tumor, accession of an aneurysm for surgical clipping. The location of a craniotomy is dictated by the “surgical approach” to the pathology. As a general rule, the location of the craniotomy provides the shortest path to the surgical target in consideration of the surrounding brain structures and blood vessels (that may be stressed or retracted during the access portion of the procedure).
Below are generalizations (in light of the wide variety of craniotomy options):
- This procedure is performed under general anesthesia (unless special circumstances dictate otherwise).
- The patient is positioned on the OR table for ease of access to the site of the craniotomy (either supine or prone). The patient’s head is then secured to the OR table with a clamp-like device. In trauma cases, the head may simply be placed on a cushioned headrest.
- The head is then shaved and an incision marked according to the planned approach. Dr. Osborn utilizes stereotactic guidance* to assure that the incision is a “best fit” for the procedure at hand.
- After anesthetizing the skin, the surgeon makes the incision and elevates the skin and muscle from their bony attachments.
- Burr holes are placed in standard positions.
- A sagittal saw (“craniotome” or “router”) is then utilized to “connect the dots” (burr holes). The “bone flap” is then elevated as a single unit, exposing the underlying dura (leathery outer covering of the brain).
- The dura is then opened and the specific procedure performed (hematoma evacuation, brain tumor resection, for example).
- At procedure close, the dura is reapproximated with suture (sewn closed), and the bone flap is secured to the native skull with titanium plates and screws.
- The overlying soft tissues are similarly closed in anatomical layers.
* Imaging-based GPS-like guidance system for real-time intraoperative localization. Such systems are used for both craniotomies and biopsies.
WHAT YOU WANT TO KNOW
“How long does a craniotomy take, on average?”
Loaded question. The answer is wholly dependent on the extent of the surgical pathology. In general, hematoma evacuations take 60-90 minutes while tumor resections may take 3-4 hours. Tumors of the posterior fossa (particularly those in close proximity to the brainstem) may require extended hours in the operating room. The goal of a surgeon is to attack the pathology efficiently, complete the resection as safely yet as comprehensively as possible, at the same time, minimizing operative time.
“How long will I be in the ICU after surgery?”
Your length of stay in the ICU is determined by your clinical status (how you are faring neurologically and how well your pain is controlled) and imaging study results (MRI or CT). If there is residual blood on the postoperative CT scan for example, you may stay in the ICU for an additional 24 hours (as a precautionary measure, in the event of further bleeding).
“Seems like a painful operation. Is it?”
Surprisingly not. Abdominal surgery and low back (lumbar) procedures are associated with a significantly greater amount of pain than cranial procedures. Patients typically complain of headache (decreasing in intensity) for 5-7 days. Sometimes, in the wake of a frontal craniotomy, patients will experience transient difficulty (and pain) with chewing as the temporalis muscle (on the side of the head) is cut. This muscle is sewn back together at procedure close.
“What are the potential risks and complications associated with a craniotomy?”
As with every operation, the risks are specific to the procedure performed. With brain surgery, the risks are related to the specific region of the brain in which lies the pathology. Remember, distinct regions of the brain are responsible for discrete functions. This is an oversimplification of course as there is much overlap and interconnectivity between the lobes (and hemispheres) of the brain. Nevertheless, with a high degree of accuracy, a neurosurgeon will be able to advise you of potential postoperative neurologic deficits based solely on the location of the lesion.
An age-old adage amongst neurosurgeons: “It’s much more important to know where something is than what it is.” That said, if a craniotomy is being performed to remove a brain tumor in the occipital lobe, one should expect visual abnormalities postoperatively. Frontal lobe? Personality, speech and potentially motor deficits. You get the picture.
Other risks of a craniotomy include:
- Hemorrhage (potentially necessitating reoperation)
- Cerebral edema (swelling) from intraoperative manipulation/brain retraction
- Wound infection
- Anesthetic complications (associated with all procedures performed under general anesthesia)
- Deep venous thrombosis (DVT) or pulmonary embolism (PE): even subtle amounts of brain manipulation increase one’s propensity to form blood clots. For this reason, Dr. Osborn prescribes mini-dose heparin as prophylaxis immediately following surgery.
“My friend had a craniotomy and “has a metal plate” in his head. Is this true? If so, can I safely go through a metal detector at the airport?”
Years ago, various methods were employed to close the bony (skull) defect post-craniotomy. Originally, the bone flap was affixed to the native skull with suture. Wire mesh and stainless steel “plates” have been used as bone substitutes particularly in the case of missile injuries (gun shot wounds) when the skull is fractured into numerous pieces and therefore cannot be reconstructed. Nowadays, the bone flap is routinely secured to the skull with small titanium “plates” (measuring 3 mm in width at varied lengths) and 4-5 mm bone screws as is seen here. Likely your friend has the latter-mentioned titanium “plates,” but this remains a source of confusion and certainly an interesting topic of conversation in the airport security line.
That said it is not problematic for a patient who has undergone a craniotomy to pass through the airport metal detectors. The titanium alloys from which the plates are fabricated are typically undetectable by virtue of their metallic properties and due to their small size. Aneurysm clips are similarly safe and pass undetected.