An awake craniotomy is a neurosurgical procedure where the patient is conscious or lightly sedated during part of the operation. This technique is primarily used to remove tumors near “eloquent” areas of the brain that control functions like speech or movement. The procedure itself does not hurt because brain tissue cannot register pain. Patients are kept awake for functional mapping, which maximizes tumor removal while preserving neurological function.
Why the Brain Cannot Feel Pain
The brain tissue, the site of tumor removal, does not contain nociceptors—the specialized nerve fibers that transmit pain signals. Pain is the subjective experience the brain creates after interpreting signals from these nociceptors located elsewhere in the body. The protective layers surrounding the brain, including the scalp, skull, and meninges, are richly supplied with nociceptors and are highly sensitive to pain. Once the surgeon navigates past these external layers, manipulation of the brain tissue occurs without causing discomfort.
How Anesthesia Prevents Pain During the Procedure
Managing pain in the sensitive scalp, skull, and meninges is the primary focus of the anesthetic team. Before the incision, a regional scalp block is performed, similar to a dental block, but for the entire head. This involves injecting long-acting local anesthetics, such as lidocaine and bupivacaine, around the nerves supplying the scalp. This nerve block numbs the skin and bone, allowing the surgeon to make the incision and remove the bone flap without pain. Conscious sedation, or Monitored Anesthesia Care (MAC), is also used during the most stimulating parts of the surgery, such as the initial opening and final closing. Medications like propofol or dexmedetomidine are infused to maintain relaxation, control anxiety, and reduce awareness of the surrounding activity.
What the Patient Experiences While Awake
Patients often describe feeling pressure, vibration, and unusual sounds, but not sharp pain. While the surgical team works on the skull, the patient hears the loud mechanical sounds of the drill and suction. They may feel the physical sensation of pushing or pulling on the tissue, which is perceived as pressure, even though the local anesthetic prevents pain. The most distinctive part of the experience is functional brain mapping, which requires the patient to be awake. During mapping, the surgeon uses a low-level electrical current to stimulate the exposed brain. The patient performs tasks, such as talking, counting, or moving a limb, and reports any changes. This direct communication ensures the tumor is removed while preserving vital functions. If a patient reports discomfort or anxiety, the anesthesiologist immediately adjusts the sedation or administers medication, giving the patient a sense of control.
Recovery and Post-Operative Management
Once the surgery is complete, the patient is fully awakened for transfer to the recovery unit. Post-operative pain is expected and managed aggressively. This pain originates from the surgical incision site, muscle manipulation, and the bone flap, all of which contain pain receptors. Pain management uses a multimodal approach, combining local and systemic medications. This includes non-opioid medications and, when necessary, intravenous or oral opioids, to keep the patient comfortable while allowing for continuous neurological monitoring. Post-craniotomy pain is common and generally moderate, often reporting low scores immediately following the procedure due to residual local anesthesia. Patients are closely monitored, and the hospital stay is typically short, focusing on safe pain control before discharge.