Different strategies in the management of thalamic space-occupying lesions

Introduction

Thalamic space-occupying lesions (SOL) are considered challenging for microsurgical removal. Unfortunately, the pathological features of lesions occurring in the thalamic region are different with a wide variation in clinical behavior and outcome. Although microsurgery is still the gold standard in the management of these lesions through different approaches, questions remain whether surgery is feasible and safe in these patients and what are the alternatives? It is well known that stereotactic techniques may be favorable especially in cystic, small, multiple lesions and in combination with adjuvant therapy. Transventricular endoscopic approach is also an alternative technique to combine tumor biopsy and treatment of hydrocephalus.

Aim of the study

The identification of the different procedures for the management of thalamic SOL in respect to the age of the patient, the clinical condition, and the site of the lesion as well as its extent and pathology.

Patients and methods

This prospective study included 35 patients having thalamic lesions with a mean age of 27 years old who were treated with different approaches including microsurgical, stereotactic, and endoscopic approaches. The clinical outcome was assessed as the same, improved, deteriorated, or died in comparison to the initial clinical status, while the radiological control was measured as no gross residual, residual < 10% and residual > 10%. Chi-square test was used to test the association between two categorical variables.

Results

Thirty-five patients were included in this study, 20 were males and 15 were females. Eight cases were children, and 27 cases were adults. The most common clinical presentation was contralateral hemiparesis. The most common pathology was pilocytic astrocytoma. Radiological studies showed that the total thalamic type was the most common topographic variant and that 10 cases had hydrocephalus treated with CSF diversion procedures. For the definitive lesion, 2 cases underwent endoscopic biopsy and cystoventriculostomy and 18 cases had stereotactic technique in the form of biopsy, aspiration, and ommaya reservoir application, while 15 cases had microsurgery through different approaches with stereotactic technique preceding surgery in 2 of them.

Conclusion

The main factors involved in choosing the appropriate approach included nature of the lesion (solid or cystic, multiplicity), suspected pathological type, and diffusion tensor imaging. Abscesses are best treated with stereotaxy, while non-neoplastic cystic lesions (other than abscesses) related to the ventricles are best treated with endoscopy. For the remaining pathologies, maximum surgical removal is the best management. Best lesion control was provided by microsurgery.

Trial registration

ISRCTN 1380 registered 6/11/2018

Testing the Reliability of BOLD-fMRI Motor Mapping in Patients with Cerebral Arteriovenous Malformations by Electric Cortical Stimulation and Surgery Outcomes

OBJECTIVE

To test the reliability of blood oxygenation level-dependent functional magnetic resonance imaging (fMRI) in the primary hand motor cortex (M1) among patients with arteriovenous malformations (AVMs) by electric cortical stimulation (ECS) and surgery outcomes.

METHODS

Forty-three patients with AVMs involving/adjacent to M1 underwent blood oxygen level-dependent fMRI (BOLD-fMRI) with repetitive finger-to-thumb opposition movements. The generated image sets were processed on the iPlan 3.0 workstation. A site-by-site comparison between the fMRI and ECS maps was performed with the aid of neuronavigation. Surgical outcomes were analyzed as the change between preoperative and postoperative muscle strength (MS). Finally, fMRI sensitivity was calculated, and correlations of lesion-to-activation distances (LAD) and surgery outcomes were analyzed.

RESULTS

The highest activation location was found in the ipsilateral M1in 40 patients (93%). The highest activation relocated in the contralateral M1area in one patient (2.3%). No motor activation was found in the other 2 (4.7%) patients. ECS results were positive in 34 patients (85%, 34/40). The fMRI sensitivity was calculated as 85%. In total, 18 patients (41.9%) had worsened MS 1 week after surgery. Eight patients (18.6%) suffered from permanent muscle strength deterioration 6 months later. Moreover, an LAD ≤5 mm was significantly associated with permanent MS deterioration (P = 0.039).

CONCLUSION

BOLD-fMRI exhibits high sensitivity in motor mapping in patients with AVMs. LAD ≤5 mm may be associated with permanent MS deterioration in patients with AVM close to the motor cortex.

Gamma Knife surgery for basal ganglia and thalamic arteriovenous malformations

Object

Gamma Knife surgery (GKS) has emerged as the treatment of choice for small- to medium-sized cerebral arteriovenous malformations (AVMs) in deep locations. The present study aims to investigate the outcomes of GKS for AVMs in the basal ganglia and thalamus.

Methods

Between 1989 and 2007, 85 patients with AVMs in the basal ganglia and 97 in the thalamus underwent GKS and were followed up for more than 2 years. The nidus volumes ranged from 0.1 to 29.4 cm3 (mean 3.4 cm3). The mean margin dose at the initial GKS was 21.3 Gy (range 10–28 Gy). Thirty-six patients underwent repeat GKS for residual AVMs at a median 4 years after initial GKS. The mean margin dose at repeat GKS was 21.1 Gy (range 7.5–27 Gy).

Results

Following a single GKS, total obliteration of the nidus was confirmed on angiograms in 91 patients (50%). In 12 patients (6.6%) a subtotal obliteration was achieved. No flow voids were observed on MR imaging in 14 patients (7.7%). Following single or repeat GKS, total obliteration was angiographically confirmed in 106 patients (58.2%) and subtotal obliteration in 8 patients (4.4%). No flow voids on MR imaging were observed in 18 patients (9.9%). The overall obliteration rates following one or multiple GKSs based on MR imaging or angiography was 68%. A small nidus volume, high margin dose, low number of isocenters, and no history of embolization were significantly associated with an increased rate of obliteration. Twenty-one patients experienced 25 episodes of hemorrhage in 850 risk-years following GKS, yielding an annual hemorrhage rate of 2.9%. Four patients died in this series: 2 due to complications of hemorrhage and 2 due to unrelated diseases. Permanent neurological deficits caused by radiation were noted in 9 patients (4.9%).

Conclusions

Gamma Knife surgery offers a reasonable chance of obliterating basal ganglia and thalamic AVMs and does so with a low risk of complications. It is an optimal treatment option in patients for whom the anticipated risk of microsurgery is too high.