Cavernous malformation (CM) accounts for about 20% of intracranial cavernous hemangiomas [1], which mostly occur in the pontine brain and are associated with high surgical risk due to their deep location adjacent to important nuclei, conduction tracts and vascular structures. In recent years, with the development of neuroimaging, neuronavigation, neurophysiological monitoring and microneurosurgery techniques, the success rate of surgery has improved significantly. From February 2004 to June 2008, 12 cases of pontocerebral cavernous hemangioma were treated in our department, and we would like to discuss their surgical indications and surgical approaches with our preliminary surgical experience. 1. Clinical data 1.1 General data 8 male cases and 4 female cases. Age 21-49 years old, average 35 years old. All patients had one or more hemorrhages, mainly manifested as dizziness and headache in 9 cases, recurrent hemianesthesia in 6 cases, choking in 3 cases, hemiplegia in 2 cases, facial palsy in 3 cases, diplopia in 1 case. 8 cases had a slow onset with progressive worsening of symptoms, and 2 cases had an acute onset with formation of fourth ventricular hematoma. The duration of the disease ranged from 10 days to 3 months, with an average of 2.3 months. 1.2 Neuroimaging All 12 patients underwent cranial CT and MRI, 3 had digital subtraction angiography (DSA) and 4 had magnetic resonance angiography (MRA), with high signal in T1- and T2-weighted phases or mixed signal in T2-weighted phases, with ring-shaped and irregular low-signal areas around and within the area, and iron-containing heme deposits with clear borders. Solid portions can be seen, with inconspicuous enhancement and CT manifestations of hemorrhage or hematoma (Figure A, B, C). The maximum diameter of the lesion was 1.5 cm-4 cm. 11 cases were located in the dorsal part of the pontine brain and 1 case was located in the ventral part of the pontine brain. The lesions were left-sided in 5 cases and right-sided in 7 cases. 1.3 Surgical approach In the 11 cases with CM located dorsal to the pontocerebrum, a suboccipital median transverse rhombic fossa approach was used. The incision was made from 2 cm above the external occipital ridge along the midline down to the spinous process of the second cervical vertebra, and the base of the fourth ventricle was exposed through the medullary fissure of the cerebellum, and the cerebellar earth was incised if necessary. A slightly raised striated structure, the medullary stripe, can be identified during surgery and is the demarcation between the pontine and medulla oblongata. Above the medullary striae, the lesion markers were searched for. In this group of patients, the lesions had yellow or yellow-brown areas on the surface, more than 2 mm from the central sulcus, avoiding injury to the medial longitudinal bundle, selecting the thinnest longitudinal incision, entering the hematoma cavity, aspirating the hematoma to obtain an operating space, and carefully excising the lesion along its periphery. For CM located ventral to the pontocerebrum, a posterior suboccipital sigmoid sinus approach is used, with an inverted “L”-shaped incision behind the suboccipital auricle. During the operation, cerebrospinal fluid is first released from the cerebellar medullary pool, the cerebellar hemispheres are gently pulled to expose the V, VII, VIII and posterior group of cranial nerves, and the lesion is excised by passing through the nerve gap and making a longitudinal incision through the yellowish pontocerebral tissue. For the small blood supply arteries and reflux veins around the lesion, they should be cut off after weak electrocoagulation, and constantly flushed with water to cool down and avoid thermal injury, and a small amount of bleeding from the trauma surface can be compressed with hemostatic gauze to stop bleeding and avoid extensive electrocoagulation. 2. Results All 12 patients had total microscopic excision of the lesion, and the postoperative pathology was confirmed as CM. microscopic examination showed that it consisted of irregular sinusoidal or cellular vascular lumen with a diameter of more than 1 mm, accompanied by thrombosis and mechanization. The vessel wall was composed of a thin fibrous outer membrane and a glassy collagen matrix. Smooth muscle and elastin fibers are absent. The lesion was surrounded by a layer of glial tissue rich in iron-containing heme phagocytes. Among the 12 patients, clinical symptoms improved in 6 cases after surgery, and dizziness, headache and recurrent hemianesthesia disappeared, and hemiparesis was reduced; 3 patients who had recovered normal before surgery did not develop new symptoms after surgery; facial palsy worsened in 1 case after surgery; 1 case had limited abduction of the affected eye after surgery; 1 case developed dyspnea and mild consciousness impairment on the third day after surgery, and improved after ventilator-assisted breathing with tracheal intubation, and stabilized two days later The ventilator was discontinued and the tracheal intubation was withdrawn. 5 hours later, the patient again developed dyspnea and impaired consciousness with high body temperature, unequal pupils bilaterally, gastrointestinal bleeding and decreased blood pressure, and died after resuscitation. Three months after surgery, MRI review was obtained in 9 cases, and no lesions were seen, and brainstem tissue imaging was well repaired. 3, Discussion Because of the high surgical risk of brainstem CM, the indication for surgery should be determined with full consideration of its natural history, weighing the risks and benefits.Kupersmith et al [2] reported that the annual bleeding and rebleeding rates of 37 cases of brainstem CM were about 2.4% and 5.1%.Porter et al [3] summarized 100 cases of brainstem CM and concluded that after hemangioma bleeding, rebleeding was more likely to occur, with annual bleeding Ferroli et al [4] reported 52 cases, with annual bleeding and rebleeding rates of 3.8% and 34.7%, respectively; Wang Loyal et al [5] reported 137 cases, with annual bleeding and rebleeding rates of 6% and 60%, respectively. Because of the high rate of rebleeding in brainstem CM, an important indication for surgical treatment of pontine CM is focal hemorrhage. Furthermore, Ferroli et al [4] mentioned that despite the traditional view that the increase in lesion volume is not related to mitosis of endothelial cells, studies have shown that endothelial cells in CM are always in a proliferative cycle. Therefore, Ferroli et al. were cautious about conservative treatment, arguing that bleeding in brainstem CM is not the only indication for surgery, and that it should be managed aggressively, weighing the pros and cons according to the patient’s specific situation. In fact, most brainstem CM is suitable for surgical treatment because of repeated intratumoral hemorrhage, which has gradually broken down to the cortical surface and is partially visible to the naked eye. All 12 cases in this group had one or more hemorrhages, among which 2 cases of acute hemorrhage had one case in which a hematoma was formed during the second hemorrhage, with an interval of more than 20 days between the second hemorrhage. The rest had recurrent or progressive worsening of clinical symptoms. From the intraoperative view, the tumors were located on the surface of the brainstem up to about 2 mm deep, and some of them had protruded into the floor of the four ventricles. Our group followed the following surgical indications: (1) progressive focal neurological dysfunction; (2) intratumoral hemorrhage causing clinical neurological dysfunction; (3) lesions close to the surface of the brainstem (usually within 3 mm); and (4) significant occupying effect due to internal hemorrhage of the lesion. The timing of surgery is an important factor in the degree of postoperative neurological recovery of the patient. According to Wang Loyal [5], emergency surgery is required for those with impaired consciousness and imaging studies showing a tense hematoma. In cases of symptomatic hemorrhage and MRI showing an occupying effect, surgery should be performed as early as possible, when the hematoma is not fully mechanized and the surrounding tissues are still mildly vitreous and fibrotic, and the surgery is easy to perform and effective. Steinberg et al [7] suggested that surgery should be performed around 4 weeks after bleeding from the lesion, so that the hematoma has started to liquefy and can be easily absorbed. zausinger et al [8] reported that the average interval between the first bleeding and surgery was 9 months, and most of the patients in this group showed short-term clinical improvement after surgery, thanks to the decompression effect of surgical removal of the liquefied blood, thus suggesting that Surgical treatment is more beneficial in the subacute phase. Two cases in this group had an acute onset, one with a hematoma formed at the first bleeding, which was pathologically confirmed as CM postoperatively, and one with a hematoma formed at the second bleeding, which was more than 20 days apart. In both cases, emergency surgery was performed within 24 hours, and intraoperatively, it was found that after removing the hematoma, the space for resection of CM became larger and the field of view became clearer, which was conducive to the protection of important tissues and blood vessels. 10 cases had a disease duration of 10 days to 3 months, and intraoperatively, we found that the lesion was clearly defined and easier to resect. Therefore, we believe that those with bleeding lesions that are indicated for surgery should be operated as early as possible because early removal of the hematoma has the following advantages: the presence of the hematoma facilitates identification and can provide a pathway for surgery; expansion of the space after removal of the hematoma facilitates operation; removal of the hematoma and release of compression can block secondary damage to the brainstem by the hematoma and its harmful derivatives; avoid rebleeding; and avoid mechanization of the hematoma that makes surgery more difficult. Most operators choose the approach based on the relationship between the hemangioma and the ventricular canal surface of the brainstem or the soft membrane surface of the brainstem, and Brown et al [9] described the “two-point approach” to determine the best approach, in which the line between the center of the hemangioma and the closest point of the hemangioma to the brainstem surface, extending outward, is the best approach. Tanriover et al [10] concluded that the difference between the two approaches lies in the exposure of the lateral saphenous fossa and Luschka’s foramen, and that the transcerebellar medullary fossa approach allows for full exposure of the lateral saphenous fossa and Luschka’s foramen without incising the cerebellum. The transcerebellar medullary fissure approach fully exposes the lateral saphenous fossa and Luschka foramen without incising the cerebellum; incising the cerebellar earthworms can cause the earthworm part of the fissure syndrome. In our 11 cases, we used a transcerebellar medullary approach or only a small incision of the cerebellar earthworms (within 1 cm), and no postoperative manifestations of earthworm fracture syndrome were observed. The upper and lower triangle of the facial colliculus is a safe area to enter the brainstem, and the facial colliculus, central colliculus, medulla and cerebellar horn are used as anatomical landmarks. Incision of the brainstem in these two regions avoids damage to the facial nerve fibers and abducens nuclei and reduces postoperative complications. The medial border of the two triangles mentioned above is 2 mm lateral to the median sulcus, with the aim of avoiding damage to the medial longitudinal tract [11]. Only if the lesion is located ventral or postero-lateral, a posterior approach to the inferior temporal or suboccipital ethmoid sinus is used. There was only one case in our group. the CM had no envelope but was well-defined and it was surrounded by a yellow-stained glial hyperplastic band, which was a good marker to find the location of the lesion. The hematoma cavity formed after CM hemorrhage in the pontocerebrum becomes a natural barrier and surgical access to the lesion boundary and pontocerebral tissue, and surgery should strictly follow this interface to avoid pontocerebral injury and residual lesions. Such cases can be excised completely, not in pieces, as the latter is prone to hemorrhage and residual Pontocerebral CM is prone to limb function, respiratory function and cerebral neurological dysfunction after surgery. The most serious and dangerous complication is respiratory dysfunction, and a case of death in this group was considered to be caused by respiratory dysfunction due to postoperative edema, and death was caused by discontinuing the ventilator after reintubation and premature extubation. Therefore, close postoperative monitoring and timely and adequate ventilator treatment are very important. Most of the other symptoms, such as eye movement disorders, can be recovered by systematic neurological rehabilitation, and one case of adductor nerve palsy and facial palsy aggravation in this group recovered gradually. In conclusion, the correct selection of surgical indications and surgical access and the removal of pontocerebral CM by microsurgical techniques are safe and effective.