Pontine-mesencephalic cavernomas: indications for surgery and operative results

Long-term outcomes after surgery for brainstem cavernous malformations: analysis of 46 consecutive cases

OBJECTIVE

The objective of this study was to evaluate the long-term outcomes after resection of brainstem cavernous malformations (BSCMs) and to assess the usefulness of the Lawton grading system in these cases.

METHODS

This retrospective study analyzed 46 consecutive patients with BSCMs operated on between July 1990 and December 2020. Outcomes at the last follow-up were defined as favorable (modified Rankin Scale [mRS] score 0-2) or unfavorable (mRS score > 2).

RESULTS

The study cohort comprised 24 men (52%) and 22 women (48%), ranging in age from 8 to 78 years old (median 37 years). In 19 patients (41%), the preoperative mRS score was > 2. All patients had hemorrhagic BSCM. There were 12 (26%) mesencephalic, 19 (41%) pontine, 7 (15%) medullary, and 8 (17%) cerebellar peduncle lesions, with a maximal diameter ranging from 5 to 40 mm (median 15 mm). In total, 24 BSCMs (52%) had bilateral extension crossing the brainstem midline. Lawton grades of 0, I, II, III, IV, V, and VI were defined in 3 (7%), 2 (4%), 10 (22%), 11 (24%), 8 (17%), 7 (15%), and 5 (11%) cases, respectively. Total resection of BSCMs was attained in 43 patients (93%). There were no perioperative deaths. Excluding the 3 most recent cases, the length of follow-up ranged from 56 to 365 months. The majority of patients demonstrated good functional recovery, but regress of the preexisting oculomotor nerve deficit was usually incomplete. No new hemorrhagic events were noted after total resection of BSCMs. In 42 patients (91%), the mRS score at the time of last follow-up was ≤ 2 (favorable outcome), and in 18 (39%), it was 0 (absence of neurological symptoms). Forty-four patients (96%) demonstrated clinical improvement and 2 (4%) had no changes compared with the preoperative period. Multivariate analysis revealed that only lower Lawton grade had a statistically significant independent association (p = 0.0280) with favorable long-term outcome. The area under the receiver operating characteristic curve for prediction of favorable outcome with 7 available Lawton grades of BSCM was 0.93.

CONCLUSIONS

Resection of hemorrhagic BSCMs by an experienced neurosurgeon may be performed safely and effectively, even in severely disabled patients. In the authors' experience, preexisting oculomotor nerve palsy represents the main cause of permanent postoperative neurological morbidity. The Lawton grading system effectively predicts long-term outcome after surgery.

The brainstem and its neurosurgical history

Brainstem is one of the most complex structures of the human body, and has the most complex intracranial anatomy, which makes surgery at this level the most difficult. Due to its hidden position, the brainstem became known later by anatomists, and moreover, brainstem surgery cannot be understood without knowing the evolution of ideas in neuroanatomy, neuropathology, and neuroscience. Starting from the first attempts at identifying brainstem anatomy in prehistory and antiquity, the history of brainstem discoveries and approach may be divided into four periods: macroscopic anatomy, microscopic anatomy and neurophysiology, posterior fossa surgery, and brainstem surgery. From the first trepanning of the posterior fossa and later finger surgery, to the occurrence of safe entry zones, this paper aims to review how neuroanatomy and brainstem surgery were understood historically, and how the surgical technique evolved from Galen of Pergamon up to the twenty-first century.

Impact of Timing of Intervention Among 397 Consecutively Treated Brainstem Cavernous Malformations

BACKGROUND

Surgical resection of brainstem cavernous malformations (BSCMs) is challenging, and patient selection and timing of intervention remain controversial.

OBJECTIVE

To evaluate the impact of surgical timing and predictors of neurological outcome after surgical resection of BSCMs.

METHODS

Consecutive adult patients (≥18 years) with BSCMs undergoing surgical resection between 1985 and 2014 by the senior author (RFS) were retrospectively reviewed. Patient demographics, lesion characteristics, imaging results, surgical approach, and perioperative and long-term neurological morbidity were analyzed.

RESULTS

Data were analyzed for a total of 397 adult patients (160, 40% male). On univariate analysis, a greater proportion of patients treated within 6 weeks of hemorrhage had an improved Glasgow Outcome Scale score (P = .06). On logistic regression analysis, patients treated within 6 weeks of hemorrhage experienced improved clinical outcomes (odds ratio = 1.73; 95% confidence interval = 1.06-2.83; P = .03).

CONCLUSIONS

Although BSCM surgery is associated with significant perioperative morbidity and mortality, favorable long-term hemorrhage rates and symptom resolution can be achieved in a carefully selected group of patients. Overall, patients treated acutely, within 6 weeks, benefited the most from surgical intervention.

The lateral infratrigeminal transpontine window to deep pontine lesions

OBJECT

Surgery of brainstem lesions is increasingly performed despite the fact that surgical indications and techniques continue to be debated. The deep pons, in particular, continues to be a critical area in which the specific risks related to different surgical strategies continue to be examined. With the intention of bringing new knowledge into this important arena, the authors systematically examined the results of brainstem surgeries that have been performed through the lateral infratrigeminal transpontine window.

METHODS

Between 1990 and 2013, 29 consecutive patients underwent surgery through this window for either biopsy sampling or for removal of a deep pontine lesion. All of this work was performed at the Department of Neurosurgery of the Istituto Nazionale Neurologico "Carlo Besta", in Milan, Italy. A retrospective analysis of the findings was conducted with the intention of bringing further clarity to this important surgical strategy.

RESULTS

The lateral infratrigeminal transpontine window was exposed through 4 different approaches: 1) classic retrosigmoid (15 cases), 2) minimally invasive keyhole retrosigmoid (10 cases), 3) translabyrinthine (1 case), and 4) combined petrosal (3 cases). No deaths occurred during the entire clinical study. The surgical complications that were observed included hydrocephalus (2 cases) and CSF leakage (1 case). In 6 (20.7%) of 29 patients the authors encountered new neurological deficits during the immediate postoperative period. All 6 of these patients had undergone lesion removal. In only 2 of these 6 patients were permanent sequelae observed at 3 months follow-up. These findings show that 93% of the patients studied did not report any permanent worsening of their neurological condition after this surgical intervention.

CONCLUSIONS

This retrospective study supports the idea that the lateral infratrigeminal transpontine window is both a low-risk and safe corridor for either biopsy sampling or for removal of deep pontine lesions.

Brainstem Cavernous Malformations

BACKGROUND:

Once considered inoperable lesions in inviolable territory, brainstem cavernous malformations (BSCM) are now surgically curable with acceptable operative morbidity. Recommending surgery is a difficult decision that would be facilitated by a grading system designed specifically for BSCMs that predicted surgical outcomes.

OBJECTIVE:

Informed by our efforts to develop a supplementary grading system for arteriovenous malformations, we hypothesized that a similar system might predict long-term outcomes and guide clinical decision-making.

METHODS:

A consecutive, single-surgeon series of 104 patients was used to assess preoperative clinical and imaging predictors of microsurgical outcomes. Univariable logistic regression identified predictors and a multivariable logistic regression model tested the association of the combined predictors with final modified Rankin Scale scores. A grading system assigned points for lesion size, location crossing the brainstem's midpoint, presence of developmental venous anomaly, age, and time from last hemorrhage to surgery.

RESULTS:

Average maximal diameter of BSCMs was 19.5 mm; 50% crossed the axial midpoint; 54.8% had developmental venous anomalies; mean age was 42.1 years; and median time from last hemorrhage to surgery was 60 days. One patient died (0.96%), and 15 patients (14.4%) experienced worsened cranial nerve or motor dysfunction, of which 10 increased their modified Rankin Scale scores (9.6%). BSCM grades ranged from 0 to 7 points and predicted outcomes with high accuracy (receiver operating characteristic = 0.86, 95% confidence interval: 0.78-0.94).

CONCLUSION:

Rather than developing a grading system for all cerebral cavernous malformations that is weak with BSCMs, we propose a system for the patients who need it most. The BSCM grading system differentiates patients who might expect favorable surgical outcomes and offers guidance to neurosurgeons forced to select these patients.

Surgical management of pediatric brainstem cavernous malformations

OBJECT

The goal of this study was to evaluate surgical outcomes of pediatric brainstem cavernous malformations (CMs) and identify the risk factors associated with postoperative full recovery and rebleeding.

METHODS

The clinical charts and radiographs from a series of 52 pediatric patients (37 male and 15 female; mean age 12.2 years; range 1-17 years) who underwent surgery for brainstem CMs between 1996 and 2011 were reviewed. Follow-up evaluation measures were obtained retrospectively. Neurological function was evaluated using the modified Rankin Scale (mRS) score.

RESULTS

The lesion locations among the 52 patients included the midbrain (n = 7, 13.5%), pons (n = 38, 73.1%), and medulla (n = 7, 13.5%). The mean duration of symptoms was 18.5 months, and the preoperative annual hemorrhage and rebleeding rates were 12.3% and 32.5% per patient-year, respectively. The mean lesion size was 2.1 cm. Gross-total resection without surgery-related death was achieved in 49 patients (94.2%). Immediate postoperative reduced neurological function was observed in 17 patients (32.7%). Surgical morbidities developed in 25 patients (48.1%) and remained in 11 patients (21.2%) after 7.9 years of follow-up. The mean mRS scores at admission, discharge after surgery, 3 and 6 months postsurgery, and recent evaluation were 2.0, 2.3, 2.0, 1.5, and 1.0, respectively. The postoperative mRS scores at 6 months (p < 0.001) and on recent evaluation (p < 0.001) were significantly lower than those at admission. Postoperative rebleeding occurred in 2 patients, and the postoperative annual rebleeding rate was 0.5% per patient-year. By the most recent evaluation, 10 patients (19.2%) had achieved full recovery and all patients were either improved (n = 32, 61.5%) or unchanged (n = 20, 38.5%). The adverse predictors for full recovery included age ≥ 12 years (HR 0.230, p = 0.021), ≥ 2 preoperative hemorrhages (HR 0.124, p = 0.048), and poor preoperative status (HR 0.197, p = 0.040). An HR < 1 predicted poor complete recoveries. The single risk factor predicting postoperative rebleeding was incomplete resection (χ2 = 4.340, p = 0.037).

CONCLUSIONS

Fair outcomes for pediatric brainstem CMs could be obtained through surgery, but only a few patients achieved full recovery. Thus, to minimize surgical morbidity, surgical planning must be tailored to individual patients in all cases in which an operation is warranted. Complete resection must be attempted to reduce the risk of postoperative rebleeding. The predictors associated with complete postoperative recovery were referential for determining treatment.

Cavernous malformation of brainstem, thalamus, and basal ganglia: a series of 176 patients

BACKGROUND

Cavernous malformations (CMs) in deep locations account for 9% to 35% of brain malformations and are surgically challenging.

OBJECTIVE

To study the clinical features and outcomes following surgery for deep CMs and the complication of hypertrophic olivary degeneration (HOD).

METHODS

Clinical records, radiological findings, operative details, and complications of 176 patients with deep CMs were reviewed retrospectively.

RESULTS

Of 176 patients with 179 CMs, 136 CMs were in the brainstem, 27 in the basal ganglia, and 16 in the thalamus. Cranial nerve deficits (51.1%), hemiparesis (40.9%), numbness (34.7%), and cerebellar symptoms (38.6%) presented most commonly. Hemorrhage presented in 172 patients (70 single, 102 multiple). The annual retrospective hemorrhage rate was 5.1% (assuming CMs are congenital with uniform hemorrhage risk throughout life); the rebleed rate was 31.5%/patient per year. Surgical approach depended on the proximity of the CM to the pial or ependymal surface. Postoperatively, 121 patients (68.8%) had no new neurological deficits. Follow-up occurred in 170 patients. Delayed postoperative HOD developed in 9/134 (6.7%) patients with brainstem CMs. HOD occurred predominantly following surgery for pontine CMs (9/10 patients). Three patients with HOD had palatal myoclonus, nystagmus, and oscillopsia, whereas 1 patient each had limb tremor and hemiballismus. At follow-up, 105 patients (61.8%) improved, 44 (25.9%) were unchanged, and 19 (11.2%) worsened neurologically. Good preoperative modified Rankin Score (98.2% vs 54.5%, P = .001) and single hemorrhage (89% vs 77.3%, P < .05) were predictive of good long-term outcome.

CONCLUSION

Symptomatic deep CMs can be resected with acceptable morbidity and outcomes. Good preoperative modified Rankin Score and single hemorrhage are predictors of good long-term outcome.

Surgery of brainstem cavernous malformations

BACKGROUND

Cavernomas are vascular hamartomas made up of thin-walled, grossly dilated blood vessels lined with endothelium. Between 4 and 35 % (mean 15 %) of cerebral cavernomas are located in the brainstem making resection of these lesions one of the most challenging tasks in neurosurgery.

METHODS

Patients with cavernomas within the brainstem or deep supratentorial structures were chosen from our prospectively collected database of operated patients with brain cavernomas. The timespan of treatment was between January 1998 and June 2012. Primary outcome was defined as percentage of patients with favourable outcome (Glasgow Outcome Scale (GOS) 4 or 5) at 1 year. Secondary outcome was defined as operation-related morbidity and mortality (drop at least 1 point on GOS at 1 year).

RESULTS

A total of 37 patients underwent surgery. The mean age was 34.7 ± 11.7 years. The male to female ratio was 19:16. Thirty-two patients had a solitary lesion and 12 patients harboured multiple lesions. The Glasgow outcome score 4 or 5 was achieved after 34 operations (89.5 %). The mean follow-up was 39 months. We experienced two early post-operative deaths (5.3 %) and decrease in the Glasgow outcome scale postoperatively in 4 patients (10.5 %).

CONCLUSIONS

• Favourable outcome was achieved in 89.5 % of cases. • Although M&M appears to be relatively high, surgery is method of choice for surgically accessible lesion which has bled for the first time due to reported high rebleed rate and high probability of poor outcome after cavernoma rebleed. • Radiosurgery should be reserved for those lesions which are deemed unresectable and where surgical intervention is considered favourable to observation alone.

Symptomatic cavernous malformations of the brainstem: functional outcome after microsurgical resection

Brainstem cavernous malformations are associated with a considerable risk of hemorrhage and subsequent morbidity. This study provides a detailed work-up of clinical and radiological outcome as well as identification of prognostic factors in patients who had suffered from symptomatic hemorrhages. Patients who had undergone surgery of symptomatic BSCMs were evaluated pre- and postoperatively both neurologically and neuroradiologically supplemented by telephone interviews. Additionally, patients were scored according to the Scandinavian Stroke Scale. Multiple uni- and multivariate analyses of possible clinical and radiological prognostic factors were conducted. The study population comprised 35 patients. Mean age at operation was 39.3 ± 13.0 years with microsurgical resection of a total of 37 different BSCMs between 2002 and 2011. Median clinical follow-up was 44.0 months (range 8-116 months). Postoperative MRI showed eventually complete resection of all BSCMs. Postoperative overall outcome revealed complete resolution of neurological symptoms for 5/35 patients, 14/35 improved and 9/35 remained unchanged. 7/35 suffered from a postoperative new and permanent neurological deficit, mostly affecting the facial nerve or hemipareses with mild impairment. Pre- and postoperative Scandinavian Stroke Scale scores were 11.0 ± 2.4 and 11.4 ± 2.2 (p = 0.55). None of the analyzed factors were found to significantly correlate with patients' clinical outcome. Complete resection of brainstem cavernous malformations can be achieved with an acceptable risk for long-term morbidity and surgery-related new deficits (~20 %). Neurological outcome is mainly determined within the first 6 months after surgery. Surgical treatment of brainstem cavernous malformations is recommended in symptomatic patients, in whom the lesion is accessible for surgery.

Surgical management of brainstem cavernous malformations

Bleeding from brainstem cavernomas may cause severe deficits due to the absence of non-eloquent nervous tissue and the presence of several ascending and descending white matter tracts and nerve nuclei. Surgical removal of these lesions presents a challenge to the most surgeons. The authors present their experience with the surgical treatment of 43 patients with brainstem cavernomas. Important aspects of microsurgical anatomy are reviewed. The surgical management, with special focus on new intraoperative technologies as well as controversies on indications and timing of surgery are presented. According to several published studies the outcome of brainstem cavernomas treated conservatively is poor. In our experience, surgical resection remains the treatment of choice if there was previous hemorrhage and the lesion reaches the surface of brainstem. These procedures should be performed by experienced neurosurgeons in referral centers employing all the currently available technology.

Modern management of brainstem cavernous malformations

Over the last 2 decades, there have been dramatic advancements in our understanding of and the ability to treat brainstem cavernous malformations (BCMs). Once thought untreatable, BCMs are now being more aggressively and safely treated microsurgically as a result of advances in monitoring and imaging technologies, as well as refinement of surgical techniques. BCMs deemed inoperable are being treated with radiosurgery, and experience with dosing and targeting has improved the safety of this treatment modality as well. Much work remains to be done, and prospective randomized trials would undoubtedly further existing knowledge.

Surgical management of brainstem cavernomas: selection of approaches and microsurgical techniques

This study reviewed surgical experience with brainstem cavernomas in an attempt to define optimal surgical approaches and risks associated with surgical management. Clinical courses were retrospectively reviewed for 36 consecutive patients (12 men, 24 women; mean age, 42 years) who underwent microsurgical resection of brainstem cavernomas between 1996 and 2006. Medical records, surgical records, and neuroimaging examinations were evaluated. All 36 patients presented with > or =1 hemorrhage from the cavernomas and preoperatively displayed some neurological symptoms. Surgical approach was midline suboccipital for 16 pontine and/or medullary cavernomas under the floor of the fourth ventricle, retrosigmoid for 10 lateral mesencephalic, pontine, and/or medullary cavernomas, occipital transtentorial for 2 thalamomesencephalic and 3 mesencephalic cavernomas, combined petrosal for 2 pontine cavernomas, and other for 3 cavernomas. Complete resection according to postoperative magnetic resonance imaging was achieved in 33 of 36 patients. No mortality was encountered in this study. New neurological deficit occurred in the early postoperative period for 18 patients, but was transient in 15 of these. Neurological state as of final follow-up was improved in 16 patients (44%), unchanged in 17 (47%), and worsened in 3 (8%) compared with preoperatively. In conclusion, symptomatic brainstem cavernomas should be considered for surgical treatment. Careful selection of the optimal operative approach and a meticulous microsurgical technique are mandatory.

Brain stem cavernous malformations

We retrospectively reviewed the clinical experience of 30 patients with brain stem cavernous malformations (BSCM) treated operatively and non-operatively at our hospital between 1983 and 2005 to elucidate the natural history of BSCM and the factors that affect surgical outcome. Inpatient charts, imaging studies, operative records, and follow-up results were evaluated. The average follow up was 48.5 months. Twenty-two patients (73.3%) received surgical extirpation and of these 86.4% improved or stabilized and 13.6% deteriorated with permanent or severe morbidity. There was no mortality. Size, preoperative status, and surgical timing were factors related to surgical outcome. In the non-operative group, 50% of the patients were the same or better, 25% deteriorated, and 25% died. With appropriate patient selection, resection of BSCM can be achieved with acceptable morbidity compared with the ominous natural history of these lesions.

Hemiparkinsonism due to a pontomesencephalic cavernoma: improvement after resection. Case report

Cavernous angiomas of the upper brainstem causing hemiparkinsonism are very rare. Due to their difficult-to-reach localization, brainstem cavernomas, in particular those in anterior locations, continue to present a therapeutic challenge. The authors report on a 16-year-old boy with a pontomesencephalic cavernoma who developed hemiparkinsonism and hemiparesis after hemorrhage. After complete surgical removal of the pontomesencephalic cavernoma via a pterional transsylvian approach, his symptoms resolved. Although pontomesencephalic cavernomas occupying the ventral portion of the brainstem are regarded as problematic for resection, the pterional transsylvian approach provides an excellent route for removal of cavernomas that are in contact with the ventral surface of the midbrain in the interpeduncular cistern. Surgical removal of this type of lesion is recommended because resolution of clinical symptoms, including hemiparkinsonism, can be achieved.

Does conservative management for brain stem cavernomas have better long-term outcome?

There has been a controversy in the last 15 years on the correct management of brain stem cavernomas. We have reviewed our experience of the last 10 years in a single Institution and reviewed related literature published in the last 15 years. We recorded the demographics, clinical presentation, rebleeding episodes, incidence of neurological events and outcome assessed by recording the change of the modified Rankin scale in 21 cases. Univariate analysis was applied to test the effect of demographics, and presentation on the incidence and timing of rebleeding, chance of having a new neurological event, the number of subsequent neurological events and outcomes. Six cases were treated with surgery and 15 cases were managed conservatively. We obtained follow-up data in 20 patients (95%). Mean follow-up period was 79.7 months (range: 6-244, median 70 months). There were 0.05 rebleeding events per patient-year and 0.1 episodes of neurological deterioration per patient-year. No mortality was noted in either the surgical or the non-surgical group. Three of the six surgical cases had a reoperation. The outcome was improved in one patient, unchanged in 1, and worse in 3 surgical patients. In the case of conservative management the outcome was improved in two patients, unchanged in five patients, and worse in eight patients. Outcome was worse in the case of multiple cavernomas (p = 0.012). Our findings suggest that conservative management may be appropriate in individual cases when compared with surgery, but this difference was not statistically significant enough in order to support a change in practice. The natural history of brain stem cavernomas appears more benign than previously thought.

Post-operative remnants of brainstem cavernomas: incidence, risk factors and management

INTRODUCTION

The risk of leaving a remnant after surgery for a cavernous malformation in the brainstem is generally not stressed enough, even though such remnants appear to have a high risk of re-bleeding. At least 40% of known cavernoma remnants after surgery have further bleeding episodes. A retrospective analysis of 30 patients with brainstem cavernoma who underwent surgery is presented, focusing on incidence, risk factors and management of post-surgical residuals. The sites were, medulla in three patients, pons-medulla in four, pons in 16, pons-midbrain in four and midbrain in three. All 30 patients came to our clinical observation with at least one episode of acute-onset neurological deficit and all were operated in the sub-acute phase. Only one patient had a worse stable outcome than the pre-surgical state, and 29 did better or were stable. All patients had a brain MRI scan within 72 h after surgery to confirm that complete removal had been achieved. In three, although the surgical cavity and its border appeared clean at the end of surgery, with no lesion remaining, post-operative MRI detected a residuum. These three patients were re-operated, but one had a further bleed prior to excision.

MATERIALS AND METHODS

In our series, the surgical finding of a multi-lobular cavernoma (as opposed to the more frequent finding of a discrete lesion with a thick capsule), with a thin wall and satellite nodules separated by a thin layer of apparently intact white matter, was common (seven patients). This group included the three patients with evidence of residuum on post-operative MRI. In our experience, the surgical finding of a multi-lobular cavernoma carries a higher risk of residuum and post-surgical re-bleeding.

CONCLUSION

Immediate post-operative brain MRI scans are therefore strongly recommended for their detection, especially in this group of patients, and if a residual is detected early re-intervention is less risky than the natural history.

Surgical treatment of ventral mesencephalic cavernoma

The treatment of an intrinsic midbrain tumour has always been controversial due to the precarious nature of its location. We report a rare example of a cavernoma located in the ventral mesencephalon and presented clinically as Holmes' tremor. In order to access this vital portion of midbrain, we chose a fronto-temporal trans-sylvian route via an orbito-zygomatic craniotomy. The cavernoma was removed en bloc with a longitudinal pial incision between the fronto-pontine fibers and the pyramidal tracts in the peduncle. After the operation, the tremor dramatically disappeared. Through a review and analysis of the literature, we discuss the surgical strategy for management of an anterior midbrain cavernoma. With an optimal surgical approach, fairly safe entry zones on the anterior face of the rostral brainstem may be accessible, which makes it possible for successful resection of a ventral mesencephalic cavernoma without postoperative complications.

Cavernomes du tronc cérébral: l'expérience chirurgicale du centre hospitalier Sainte-Anne

BACKGROUND AND PURPOSE

No standard treatment for brainstem cavernoma has been established because of the lack of sufficient data about the natural history of these lesions in a highly functional location with potential difficult surgical accessibility.

METHODS

We present a series of 82 brainstem cavernomas managed at the Sainte-Anne Hospital. Surgery was undertaken for 25 with stereotactic biopsy for 9 and direct surgery for 19 (3 after biopsy).

RESULTS

Surgical outcome was good or fair for 17 patients. Two patients worsened and one died. Biopsy results were disappointing with high morbidity (4 patients with 2 permanent deficits). Histological diagnostic was possible for all biopsies.

CONCLUSION

In light of these results, an active surgical attitude could be proposed for cavernomas in an accessible locations which have produced at least one previous hemorrhage. Stereotactic biopsies for suspect brainstem cavernoma must be avoided.

Surgery for mesencephalic cavernoma: case report

BACKGROUND

Intrinsic midbrain tumor has been one of the most challenging therapeutic tasks in neurosurgery because of its prognosis and risks associated with surgical procedures. We encountered a rare case of cavernoma located in the anterior-mesencephalic region presented as parkinsonism tremor.

CASE DESCRIPTION

A 42-year-old woman had a resting tremor for 10 years. This tremor involved the left shoulder and the proximal and distal limb, which was exacerbated by any attempted movement and became grossly uncontrollable. She showed a partial right ophthalmoplegia with mydriasis. Her right upper and lower extremities had normal strength, but her left extremities had three-fifth strength. Her sensation was intact. Magnetic resonance imaging demonstrated a popcorn-like rounded lesion in the right ventral midbrain adjacent to the medial cerebral peduncle. To access this anterior-medial portion of the midbrain, we chose a frontotemporal transsylvian route via an orbitozygomatic craniotomy. With a longitudinal pial incision between the frontopontine fibers and the pyramidal tracts in the peduncle, the cavernoma was totally removed en bloc. After the operation, the tremor dramatically disappeared. The muscle strength of her left lower extremity improved to four fifths, whereas the upper extremity was still the same. The preoperative left oculomotor palsy seemed to have no improvement.

CONCLUSIONS

Clinically manifested cavernoma due to repeated hemorrhage needs surgical intervention. With an optimal surgical approach, fairly safe entry zones on the anterior face of the rostral brainstem may be accessible, which provides a successful resection of a mesencephalic cavernoma without postoperative complications.

Intraoperative rupture of brainstem cavernous malformation

✓Although cavernous malformations (CMs) are an important cause of intracranial hemorrhage, the natural history of these lesions is controversial. Both retrospective and prospective studies undertaken to define risk factors for hemorrhage from CMs have consistently identified the location of a lesion as a factor that has a significant impact on the rate of rupture, and brainstem CMs consistently have a higher rate of symptomatic hemorrhage than those at other locations. The mechanism underlying this disparity in rupture rates, however, remains obscure. Most authors attribute the difference, at least partially, to the sensitivity of the brainstem to hemorrhage. Regardless, the specific factors that cause a given CM to rupture are unknown.

The authors report their first encounter with an intraoperative rupture of a CM in the brainstem. This case underscores the risks encountered during the surgical approach to brainstem CMs and may provide insight into the pathophysiological mechanisms underlying the rupture of these lesions.

Anterior transpetrosal approach for pontine cavernous angioma--case report

A 58-year-old male patient presented with headache and unsteady gait. Magnetic resonance imaging revealed hemorrhage from a pontine cavernous angioma. The patient experienced stepwise aggravation of symptoms due to repeated hemorrhages. We decided to surgically remove the pontine cavernous angioma through an anterior transpetrosal approach, since the angioma and hematoma were located near the ventrolateral surface of the pons. The brain stem was incised at a site caudal to the trigeminal nerve and the hematoma and angioma were totally removed. No additional neurological deficits were observed following surgery. Brain stem cavernous angiomas are usually removed via a trans-fourth ventricle or lateral suboccipital approach. However, these approaches may not be appropriate if the angioma is located ventrally to the pons. We propose that the anterior transpetrosal approach is the method of choice for ventrally located pontine cavernous angioma.

Multiple cavernomas of brain presenting with simultaneous hemorrhage in two lesions: a case report

BACKGROUND

Cavernomas are rare vascular lesions of the brain that can bleed. However, the risk of bleeding is lower than that of aneurysms or arteriovenous malformations. In selected cases, bleeding cavernomas require surgical management. Presented here is a case of multiple cavernomas of the brain with simultaneous bleeding in two different lesions, along with its management. Although multiple cavernomas have been described in the literature, simultaneous bleeding in two different lesions is rare.

CASE DESCRIPTION

A 52-year-old woman presented with difficulty maintaining balance, double vision, and slurred speech. She had had multiple surgeries for cavernous angioma of the brain in the past. Examination and investigations revealed two cavernomas, one in the dorsal midbrain region and one in the left occipital region. Her clinical condition deteriorated suddenly, and further evaluation revealed bleeding in both the cavernomas. The lesion in the midbrain was removed surgically. Since the lesion was in the posterior midbrain, a posterior interhemispheric approach was used with the help of frameless stereotactic navigation. Total excision was achieved. The lesion in the occipital lobe was not operated on. The patient had an uneventful recovery. It was planned to observe the progress of the occipital cavernoma by serial magnetic resonance imaging scans.

CONCLUSION

Although there may be simultaneous bleeding in two or even more lesions, surgical treatment should be undertaken for the lesions jeopardizing critical structures or exerting mass effects. Additionally, it was discovered that frameless stereotactic navigation was of immense help in delineating the lesion and for safe excision of the lesion in critical areas.

Surgical management of brainstem cavernomas

OBJECT

A careful retrospective analysis of 36 cases was performed to evaluate the pre- and postoperative rates of morbidity that occur in patients with brainstem cavernous angiomas.

METHODS

The authors evaluated immediate postoperative and follow-up outcomes with regard to clinical findings, the incidence of preoperative hemorrhage(s), location and size of the lesions, and the timing of the surgical procedure after the last hemorrhagic event. Specifically. the following parameters were analyzed: 1) number of hemorrhages; 2) the precise brainstem location (pontomesencephalic, pons, and medulla oblongata); 3) pre- and postoperative cranial nerve status; 4) pre- and postoperative motor and sensory deficits; 5) size (volume) of the lesions; and 6) pre- and postoperative Karnofsky Performance Scale (KPS) scores. Multiple hemorrhages were observed in 16 patients, particularly in those with pontomesencephalic cavernous angiomas (75%). The mean preoperative KPS score was 70.3 +/- 16.3 (+/- standard deviation). Twenty-six patients (72.2%) presented with cranial nerve impairment, 13 (36.1%) with motor deficits, and 17 (47.2%) with sensory disturbance. Volume of the lesions ranged from 0.18 to 18.18 cm3 (mean 4.75 cm3). Postoperative complications included new cranial nerve deficits in 17 patients, motor deficits in three, and new sensory disturbances in 12 patients. In a mean follow-up period of 21.5 months, KPS scores were 80 to 100 in 22 patients. Timing of surgery (posthemorrhage) and multiple hemorrhages did not influence the long-term results. Higher preoperative KPS scores and smaller-volume lesions, however, were factors associated with a better final outcome (p < 0.05). Major morbidity was related mainly to preoperative status and less to surgical treatment. The incidence of new postoperative cranial nerve deficits was clearly lower than that demonstrated preoperatively because of the brainstem hemorrhages.

CONCLUSIONS

Based on these findings, resection of brainstem cavernomas is the treatment of choice in the majority of these cases because of the high incidence of morbidity related to one or often several brainstem hemorrhages.

Microsurgical resection of brainstem, thalamic, and basal ganglia angiographically occult vascular malformations

OBJECTIVE

To evaluate the clinical results for patients who underwent resection of angiographically occult vascular malformations (AOVMs) of the brainstem, thalamus, or basal ganglia, successfully resected after it exhibited rebleeding and presented to a pial surface.

METHODS

Between January 1990 and May 1998, 56 patients with 57 deep AOVMs underwent 63 operations, at Stanford University Medical Center, to treat AOVMs of the brainstem (42 AOVMs), thalamus (5 AOVMs), or basal ganglia (10 AOVMs). The surgical approach was suboccipital midline (27 operations), far lateral suboccipital (10 operations), transsylvian (9 operations), interhemispheric transcallosal or infracallosal (8 operations), infratentorial supracerebellar (6 operations), or subtemporal (3 operations). Four patients experienced recurrent bleeding from the same lesion after surgical resection, requiring a second operation. One patient required a planned second operation, using a different approach, to completely resect the lesion, and one patient underwent two surgical procedures to resect two separate brainstem AOVMs. One patient initially underwent exploration but not resection of her AOVM, because it did not present to a pial or ependymal surface. The AOVM was successfully resected after it exhibited rebleeding and presented to a pial surface.

RESULTS

The immediate outcomes after surgery were unchanged for 31 patients (55%), worsened for 16 (29%), and improved for 9 (16%). The long-term outcomes were unchanged for 24 patients (43%), compared with their presenting grade, worse for 3 (5%), and improved for 29 (52%). Patients who had undergone previous radiotherapy or radiosurgery to treat these lesions experienced more difficult postoperative courses, and radiation necrosis was observed for two patients.

CONCLUSION

AOVMs of the brainstem, thalamus, and basal ganglia can be safely removed, with a long-term neurological morbidity rate of only 5% and a complete lesion resection rate of 93% after the initial planned resection. The use of cranial base surgical approaches and intraoperative electrophysiological monitoring contributes to successful clinical outcomes.

Intraoperative electrical stimulation for identification of cranial nerve nuclei

The purpose of this study was to evaluate the feasibility and usefulness of cranial nerve nuclei monitoring during resection of brainstem cavernous malformations. Eleven patients with brainstem cavernous malformations underwent resection of their malformations utilizing cranial nerve nuclei monitoring. Cranial nerves V and VII were monitored by placing electrodes in muscle groups innervated by these nerves and recording manipulation-induced neurotonic discharges and triggered electromyographic (EMG) activity, after electrical stimulation of the corresponding brainstem nuclei. Seven of 11 procedures (64%) with cranial nerve nuclei monitoring were noted to have cranial nerve nuclei activity corresponding to manipulation of the nuclei. The cavernous malformation was completely resected in 5 of 7 cases with cranial nerve nuclei activity and in all 4 cases without activity. In the remaining 2 cases, the cavernous malformation was not resected due to the proximity of the monitored cranial nerve nuclei to the cavernous malformation and to increasing neurotonic activity as the cavernous malformation was approached. None of the 11 patients had new permanent postoperative deficits corresponding to the cranial nerve nuclei monitored; 1 patient had a transient partial facial palsy lasting 2 days. Preliminary results indicate that cranial nerve nuclei monitoring proves useful in preserving neurologic function and reducing surgical morbidity during resection of brainstem cavernous malformations, particularly indicating when lesion resection places these nuclei at risk.

The stereotactic volumetric information: its role in two-step resection of brainstem and thalamic giant tumor. Report of three cases and technical note

BACKGROUND

A compact intracerebral tumoral lesion is usually considered to be completely resectable. Nevertheless, radical resection of a huge lesion located in a critical area may damage the surrounding compressed brain tissue. In cases with a good prognosis, a two-step removal appears to be a safer strategy.

METHODS

In three cases, two with huge brain stem lesions and one with a thalamic lesion, a two-step volumetric stereotactic resection was planned. This strategy allowed us to evaluate the amount of tumor to be removed during the first procedure and to have, during the second operation, an exact definition of the reduced mass with regard to the scar tissue and postoperative adhesions. Furthermore, we avoided significant shifting of the cerebral structures during both procedures.

RESULTS

There was a very good final recovery in the cases with brain stem lesions and a minimal deficit in the patient with the thalamic lesion. The patient with a mesencephalic lesion remained comatose for almost 2 days after the first procedure, confirming our fears about too radical a one-step resection.

CONCLUSIONS

We think that by using current techniques, it is possible to remove a well circumscribed lesion regardless of its position. This is probably easier with giant lesions where a safe trajectory can be planned. In these cases, with lesions located in very critical areas but with a good prognosis, a two-step resection appears to be a good option.

Surgical management of brain-stem cavernomas

We present a series of seven patients who were operated on for symptomatic brain-stem cavernomas. The following approaches were used: medial suboccipital (N = 4), lateral suboccipital (N = 1), subtemporal-transtentorial (N = 1), and frontal transcortical-transventricular-subchorioidal-trans velum interpositum (N = 1). Intraoperative motor (N = 4) and somatosensory (N = 1) evoked potential monitoring revealed temporary changes in 3 patients. Immediately postoperatively, the following additional deficits were observed in 6 patients: oculomotor nerve paresis (N = 2), abducens nerve paresis (N = 3), facial nerve paresis (N = 2), deafness (N = 1), and increased ataxia (N = 3). One patient died due to septic complications not related to surgery. After a mean observation time of 2 years, 2 patients had improved, 3 were unchanged, and 1 patient deteriorated as compared to his preoperative status. In conclusion, surgical treatment of brain-stem cavernomas, although carrying a significant risk of temporary neurological deterioration is recommended in symptomatic patients in whom the cavernoma seems to reach the surface of the brain-stem. Intraoperative functional topographic mapping and monitoring have proven useful tools lowering the surgical risks in these patients.

Intracranial cavernous malformations: lesion behavior and management strategies

Intracranial cavernous malformations are vascular anomalies consisting of endothelium-lined caverns filled with blood at various stages of thrombosis and organization and separated by a collagenous stroma devoid of mature vessel wall elements. They occur in an estimated 0.45 to 0.9% of the population, with male and female patients equally affected and all ages represented. They commonly manifest as seizures, gross intracranial hemorrhage, and focal neurological deficits. Lesions are frequently multiple in the same patient, and 10 to 30% are associated with familial clustering. Several reports have documented a dynamic clinical-radiological lesion behavior with de novo lesion genesis, intralesional and perilesional hemorrhage, and corresponding fluctuations in lesion size. Hemorrhagic risk and neurological disability seem to be related to multiple factors, including lesion location, age, gender, state of reproductive cycle, and previous hemorrhage. Lesions may behave aggressively with repetitive hemorrhages and cumulative disability or may remain quiescent for many years. Management strategies include expectant follow-up in patients with asymptomatic or inaccessible lesions, excision of symptomatic and accessible lesions, and radiosurgery of progressively symptomatic lesions in inoperable locations. Relevant disease-specific outcome parameters are proposed to guide clinical decisions and future research. Prospective, stratified, hypothesis-driven studies using rigorous epidemiological methods must be undertaken to delineate patient and lesion factors influencing clinical aggressiveness. Biological studies are essential to uncover strategies to predict and modify lesion behavior.