In 1944, Dandy introduced the frontolateral craniotomy for the treatment of anterior circulation aneurysms, forming the basis of the classical pterional craniotomy. Kempe, Shepard, and Swain further developed this procedure and was greatly improved and popularized by Yasargil. Because of its versatility, this approach is widely used for approaching lesions in the circulation circle of Willis and the parasellar regions as well as the frontal and temporal lobes. Although brain retraction is a commonly used technique in neurosurgery, it leads to postoperative complications; the main complication is facial paralysis caused by damage to the temporal branch of the facial nerve, which is manifested by the disappearance of forehead wrinkles and eyebrow drooping; at the same time, nerve damage leads to muscle atrophy . In a study evaluating masticatory function and facial nerve recovery after pterional approach surgery, 37.5% of patients had difficulty chewing hard food after surgery, and 25% of patients still had pain when chewing hard food 1 year after surgery . Pterional craniotomy requires complete dissection of the temporal muscles and often unnecessarily exposes large areas of the cortex. The damage to normal tissues during surgery may seriously affect the daily life and social life of patients after surgery . In the minimally invasive, personalized, patient-centered treatment process, we need to consider procedures that can reduce postoperative complications.
New surgical techniques have been proposed to reduce the exposure of pterional craniotomy, reduce hospitalization and operative times, reduce tissue trauma, create a comfortable postoperative period, lower costs, and improve esthetic and functional outcomes . Figueiredo et al. confirmed that the surgical exposure area and the approach angles gradually increased with the progression of the Sylvian fissure dissection toward the pars triangularis at the level of the anterior ascending ramus, and further dissection did not increase the exposure . Keyhole surgery is also a way to minimize damage to normal tissue. Keyhole approaches commonly used as alternatives to pterional approach include superciliary keyhole approach, supraorbital keyhole approach, and mini-pterional keyhole approach. The study has shown that the incidence of postoperative temporal atrophy was significantly lower in the mini-pterional group than in the pterional group during aneurysm surgery . Despite facial wounds, the superciliary keyhole approach provided a higher level of patient satisfaction than the pterional approach . Compared with the pterional approach group, the operative time and intraoperative blood loss in the supraorbital keyhole approach group were significantly shortened . These keyhole approaches are suitable for tumor located at the anterior cranial fossa without significant temporal extension. Keyhole approaches mentioned above are mainly applicable to extracerebral lesions and meningiomas, while endoscopic operation or endoscopic assistance is often required for intracerebral lesions. In mini-temporal craniotomy, the temporal lobe exposure will be larger than that of approached above to better expose both the temporal lobe and the Sylvian fissure region when approaching the arterial circle of Willis, which makes the en bloc resection of the temporal lobe tumors possible; however, the temporal lobe and middle cranial fossa tumor cannot be fully exposed by the above keyhole incision.
To protect arteries and nerves in the temporal region, it is necessary to dissect the muscle and periosteum together during the separation of the temporalis. Before surgeons began to intentionally protect the temporal branch of the facial nerve during craniotomy, frontalis muscle palsy occurred in 30% of patients who underwent scalp flap subgaleal elevation with separate temporalis separately elevation . The loose areolar tissue between the galea and the superficial layer of temporal fascia is where the temporal branches to the frontalis muscle run. Thus, the interfascial-subpericranial and subfascial-subpericranial techniques can retain innervation of the frontalis muscle . The hairline at the temple is also comsidered a marker, and the area behind it is safe to dissect . In the mini-temporal incision design, the frontal end of the incision never surpasses the hairline at the level of temporal line, and a one-layer skin-galea-muscle flap is detached from the cranium, effectively avoiding the injuries of facial nerve. Because the mini-temporal incision is usually small, the surgical bone window is completely located underneath the temporalis muscle, allowing it to be completely repositioned postoperatively. The cranium is usually milled in one piece with no extra bone removal, and the cranium can be restored intactly. Mini-temporal craniotomy does not extend to the frontal side of the skull, so the frontal sinus will not be invaded, reducing the possibility of postoperative cerebrospinal fluid leakage and infection. Mini-temporal incisions require less hair to be shaved, so fewer holes are required to be drilled and fewer temporalis to be separated.
With the promotion of the concept of minimally invasive surgery, the protection of brain tissue in the surgical field has become a consensus, but the protection of other tissues along the surgical path should be further promoted. Long-term postoperative pain during mastication may lead to a a dental professional than a neurosurgeon. In addition, patients may use hair to shield the atrophy of the temporalis muscle, believing that atrophy and pain are a necessary price to pay for a successful surgery. Recent articles point out that while traditional pterional may lead to a range of cosmetic and functional problems, few studies have focused on cosmetic outcomes and patient satisfaction; only 10 studies (26.31%) involved patient satisfaction with esthetics, and only 7 studies (18.42%) reported cosmetic outcomes as the primary outcome . Even the questionnaire-based postoperative assessment for cosmetic outcomes and patient satisfaction was just recently discussed in an article . Therefore, minimally invasive approaches like the mini-temporal approach have become very important. According to the previous surgical experience of our center, mini-temporal approach was used in tumor resection of temporal area, which greatly reduced the impact of normal skin, muscle, bone, and cortex during craniotomy and limited the surgical trauma to the tumor area, truly reflecting the minimally invasive concept.
Naturally, mini-temporal apporach has limitations. First, bone window size is limited, and it requires the surgeons to adjust the microscope to find the best angles. Second, when deep bony drilling in the surgical field is required, when brain edema or hematoma high intracranial occurs, or when fully dissection of the sylvian fissure is required for aneurysms, the mini-temporal approach does not provide the same convenience and safety as the classical pterional approach. Therefore, the choice between mini-temporal and classical pterional approaches should be based on the anatomical positions and clinical/ radiological features of the lesions.