Interhemispheric Transcallosal Transchoroidal Approach

Interhemispheric Transcallosal Transchoroidal Approach

Key points

1. The transchoroidal approach is a versatile approach to access lesions situated within the third ventricle predominantly behind the foramen of Monro.

2. The anatomy of the bridging veins should be studied to plan a safe and adequate craniotomy.

3. Neuronavigation could be helpful in estimating the positions of the venous structures in the approach and the ideal trajectory to the lesion in order to perform an adequate placed callosotomy.

4. The anatomy of the lesion in relation to the anatomy of the deep venous system, namely the septal, thalamostriate vein and internal cerebral veins should be carefully analyzed on the pre-operative MRI.

5. The pre-operative MRI along with DTI should be analyzed to estimate the displacement of important projection fibers in relation to the lesion.

6. Great respect needs to be given to all the venous structures and any sacrifice of a vein should be made with caution.

7. The complications related to the thalamostriate vein and its branches occur much less frequently when compared to the subchoroidal approach.

8. The thalamo-geniculate and thalamo-perforating arteries should be carefully preserved during perilesional dissection.

9. Post-resection external ventricular drainage can be helpful in avoiding early postoperative hydrocephalus.

10. In cases of diencephalic-mesencephalic lesions, steroids could be helpful in reducing edema in the early postoperative period 1).

It is a subtype of Interhemispheric approach.

This approach consists of opening the taenia fornicis of the choroidal fissure in the body of the lateral ventricle and approaching the third ventriclebetween the two internal cerebral veins. This route allows further posterior enlargement of the foramen of Monro without sacrificing any neural structures. When necessary, the anterior septal vein can be sacrificed.

Twenty adult cadaveric brains and four adult cadaveric heads were studied, using a magnification ranging from 3 times to 40 times, after perfusion of the arteries and veins with colored latex.

The choroidal fissure is a natural cleft between the thalamus and the fornix, and it is identified by following the choroid plexus in the lateral ventricle. The choroid plexus in the body of the lateral ventricle originates from the tela choroidea of the roof of the third ventricle and is apparently attached to the fornix by the taenia fornicis and to the thalamus by the taenia choroidea. The taenia is actually the ependyma that covers the internal wall of the ventricular cavity and the choroid plexus.

An understanding of the choroidal fissure is fundamental for use of the transchoroidal approach. Unlike transforaminal, subchoroidal, subforniceal, and interforniceal approaches to the third ventricle, which sacrifice some neural or vascular structures, the transchoroidal approach follows a natural route, and certainly it is one of the options to be considered when entry into the third ventricle is required 2).

see Transtemporal transchoroidal fissure approach

Ito et al demonstrate an interhemispheric transchoroidal approach for third ventricular teratoma resection. Interhemispheric dissection exposed the corpus callosum at a length of about 2 cm. A callosotomy was made to enter into the right lateral ventricle. After septal vein ligation, dissection was made of the space between the right fornix and right internal cerebral vein (ICV); thus bilateral fornix and left ICV would be retracted to the left; right choroid plexus, right ICV to the right. By this transchoroidal approach, the foramen of Monro was extended posteriorly, providing enough of a surgical corridor to resect a posteriorly located third ventricular tumor. The video can be found here: 3).

Interhemispheric transcallosal route for resection of anterior third ventricular lesions

Peker HO, Aydin I, Dinc C, Baskaya MK. Microsurgical Resection of Thalamic Astrocytomas Via Anterior Interhemispheric Transcallosal Transchoroidal Approach: Demonstrating of Technique: 3-Dimensional Operative Video. Oper Neurosurg (Hagerstown). 2018 May 1;14(5):595. doi: 10.1093/ons/opx196. PubMed PMID: 28961966.



Cossu, G., González-López, P. & Daniel, R.T. Acta Neurochir (2019).

Wen HT, Rhoton AL Jr, de Oliveira E. Transchoroidal approach to the third ventricle: an anatomic study of the choroidal fissure and its clinical application. Neurosurgery. 1998 Jun;42(6):1205-17; discussion 1217-9. PubMed PMID: 9632178.

Ito Y, Inoue T, Tamura A, Tsutsumi K. Interhemispheric transchoroidal approach to resect third ventricular teratoma. Neurosurg Focus. 2016 Jan;40 Video Suppl 1:2016.1.FocusVid.15401. doi: 10.3171/2016.1.FocusVid.15401. PubMed PMID: 26722682.

Cerebral cavernous malformation treatment

Cerebral cavernous malformation treatment

see Intracranial cavernous malformation surgery.

There have been few comparative studys of microsurgical excision vs conservative treatment of cerebral cavernous malformations (CCM) and none of them has reliably demonstrated a statistically and clinically significant difference.

A prospective, population-based study to identify and independently validate definite cerebral cavernous malformation diagnoses first made in 1999-2003 in Scottish adult residents, used multiple sources of prospective follow-up to assess adults’ dependence and to identify and independently validate outcome events.

Moultrie et al., used univariate and multivariable survival analyses to test the influence of CCM excision on outcome, adjusted for prognostic factors and baseline imbalances.

Of 134 adults, 25 underwent CCM excision; these adults were younger (34 vs 43 years at diagnosis, p = 0.004) and more likely to present with symptomatic intracranial hemorrhage or focal neurological deficit than adults managed conservatively (48% vs 26%; odds ratio 2.7, 95% confidence interval [CI] 1.1-6.5). During 5 years of follow-up, CCM excision was associated with a deterioration to an Oxford Handicap Scale score 2-6 sustained over at least 2 successive years (adjusted hazard ratio [HR] 2.2, 95% CI 1.1-4.3) and the occurrence of symptomatic intracranial hemorrhage or new focal neurologic deficit (adjusted HR 3.6, 95% CI 1.3-10.0).

CCM excision was associated with worse outcomes over 5 years compared to conservative management. Long-term follow-up will determine whether this difference is sustained over patients’ lifetimes. Meanwhile, a randomized controlled trial appears justified.

CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that CCM excision worsens short-term disability scores and increases the risk of symptomatic intracranial hemorrhage and new focal neurologic deficits 1).

Antithrombotic therapy use is associated with a lower risk of intracranial haemorrhage or focal neurological deficit from cerebral cavernous malformations than avoidance of antithrombotic therapy. These findings provide reassurance about safety for clinical practice and require further investigation in a randomised controlled trial 2).



Moultrie F, Horne MA, Josephson CB, Hall JM, Counsell CE, Bhattacharya JJ, Papanastassiou V, Sellar RJ, Warlow CP, Murray GD, Al-Shahi Salman R; Scottish Audit of Intracranial Vascular Malformations (SAIVMs) steering committee and collaborators. Outcome after surgical or conservative management of cerebral cavernous malformations. Neurology. 2014 Aug 12;83(7):582-9. doi: 10.1212/WNL.0000000000000684. Epub 2014 Jul 3. PubMed PMID: 24994841.

Zuurbier SM, Hickman CR, Tolias CS, Rinkel LA, Leyrer R, Flemming KD, Bervini D, Lanzino G, Wityk RJ, Schneble HM, Sure U, Al-Shahi Salman R; Scottish Audit of Intracranial Vascular Malformations Steering Committee. Long-term antithrombotic therapy and risk of intracranial haemorrhage from cerebral cavernous malformations: a population-based cohort study, systematic review, and meta-analysis. Lancet Neurol. 2019 Aug 6. pii: S1474-4422(19)30231-5. doi: 10.1016/S1474-4422(19)30231-5. [Epub ahead of print] PubMed PMID: 31401075.

Cystic craniopharyngioma

Cystic craniopharyngioma

Cystic craniopharyngiomas comprise more than 90% of the craniopharyngiomas.


Intracystic treatment options for cystic craniopharyngioma provide data suggestive of durable cyst shrinkage and benefit beyond a pure volume reduction due to repeated fluid aspirations. The effect however is limited to the cystic craniopharyngioma portion without an effect on the solid component. There are multiple challenges relating to technical practicalities: Multicystic occurrence may limit treatment to one cyst only and therefore this approach does not provide the clinical benefit as wished. The thickness of the cyst wall may not allow successful penetration of the scope/catheter into the cyst and different catheter designs make the correct intracystic positioning of the catheter and its holes difficult. Intraoperative ultrasound and computed tomography (CT) have aided to confirm the correct catheter position; however, volume changes during subsequent treatment may influence the intracystic catheter tip location.

Hence the prospect of a minimally invasive intervention – such as an endoscopic insertion of a catheter with a subcutaneous Ommaya reservoir – and subsequent instillation of substances inducing shrinkage of the craniopharyngioma cyst(s), seems a promising strategy 1).

Intracystic bleomycin

A search in electronic databases CENTRAL (2014, Issue 1), MEDLINE/PubMed (from 1966 to March 2014) and EMBASE/Ovid (from 1980 to March 2014) with pre-specified terms, Reference lists of relevant articles and reviews, conference proceedings (International Society for Paediatric Oncology 2005-2013) and ongoing trial databases (Register of the National Institute of Health and International Standard Randomised Controlled Trial Number (ISRCTN) register) in May 2014.

Randomized controlled trials (RCTs), quasi-randomized trials or controlled clinical trials (CCTs) comparing intracystic bleomycin and other treatments for cystic craniopharyngiomas in children (from birth to 18 years).

Two review authors independently performed the data extraction and ‘Risk of bias’ assessment. They used risk ratio (RR) for binary data and mean difference (MD) for continuous data. We planned that if one of the treatment groups experienced no events and there was only one study available for the outcome, we would use the Fischer’s exact test.

Zheng et al. could not identify any studies in which the only difference between the treatment groups was the use of intracystic bleomycin. They did identify a RCT comparing intracystic bleomycin with intracystic phosphorus 32 (n = 7 children). The trial had a high risk of bias. Survival could not be evaluated. There was no evidence of a significant difference between the treatment groups in cyst reduction (MD -0.15, 95% confidence interval (CI) -0.69 to 0.39, P value = 0.59), neurological status (Fisher’s exact P value = 0.429), 3rd nerve paralysis (Fischer’s exact P value = 1.00), fever (RR 2.92, 95% CI 0.73 to 11.70, P value = 0.13) or total adverse effects (RR 1.75, 95% CI 0.68 to 4.53, P value = 0.25). There was a significant difference in favour of the (32)P group for the occurrence of headache and vomiting (Fischer’s exact P value = 0.029 for both outcomes).

Since they identified no RCTs, quasi-randomised trials or CCTs of the treatment of cystic craniopharyngiomas in children in which only the use of intracystic bleomycin differed between the treatment groups, no definitive conclusions could be made about the effects of intracystic bleomycin in these patients. Only one low-power RCT comparing intracystic bleomycin with intracystic (32)P treatment was available, but no definitive conclusions can be made about the effectiveness of these agents in children with cystic craniopharyngiomas. Based on the currently available evidence, we are not able to give recommendations for the use of intracystic bleomycin in the treatment of cystic craniopharyngiomas in children. High-quality RCTs are needed 2).


Radioactive phosphorus 32 (P32) has been used as brachytherapy for craniopharyngiomas with the hope of providing local control of enlarging tumor cysts. Brachytherapy has commonly been used as an adjunct to the standard treatment of surgery and external beam radiation (EBR). Historically, multimodal treatment, including EBR, has shown tumor control rates as high as 70% at 10 years after treatment. However, EBR is associated with significant long-term risks, including visual deficits, endocrine dysfunction, and cognitive decline. Theoretically, brachytherapy may provide focused local radiation that controls or shrinks a symptomatic cyst without exposing the patient to the risks of EBR.

Ansari et al reviewed their experiences with craniopharyngioma patients treated with P32 brachytherapy as the primary treatment without EBR. The authors reviewed these patients’ records to evaluate whether this strategy effectively controls tumor growth, thus avoiding the need for further surgery or EBR.

Ansari et al performed a retrospective review of pediatric patients treated for craniopharyngioma between 1997 and 2004. This was the time period during which the authors’ institution had a relatively high use of P32 for treatment of cystic craniopharyngioma. All patients who had surgery and injection of P32 without EBR were identified. The patient records were analyzed for complications, cyst control, need for further surgery, and need for future EBR.

Thirty-eight patients were treated for craniopharyngioma during the study period. Nine patients (23.7%) were identified who had surgery (resection or biopsy) with P32 brachytherapy but without initial EBR. These 9 patients represented the study group. For 1 patient (11.1%), there was a complication with the brachytherapy procedure. Five patients (55.5%) required subsequent surgery. Seven patients (77.7%) required subsequent EBR for tumor growth. The mean time between the injection of P32 and subsequent treatment was 1.67 ± 1.50 years (mean ± SD).

In this small but focused population, P32 treatment provided limited local control for cyst growth. Brachytherapy alone did not reliably avert the need for subsequent surgery or EBR 3).

Case series

11 non-consecutive adult cystic craniopharyngiomas (7 recurrent lesions) have been treated with Ommaya Reservoir System (ORS), in two neurosurgical centers. ORS was placed in nine cases using minimally invasive procedures: six burr hole endoscopic insertion and three navigated electromagnetic placement; in the remaining two patients, the Ommaya reservoir was used as a shunt to prevent cyst recollection during a transcranial approach.

The main presenting symptoms were visual impairment (75%), cognitive and behavioral disorders (66.7%), hypopituitarism (38%), headache (30.8%) and hypothalamic obesity (8%). The median follow-up period was 41.4 months. In all patients, the visual function and intracranial hypertension improved after decompression. Local tumor control was accomplished in eight patients (72.7%), without the need of adjuvant treatments. The endoscopic vision carried similar rates of tumor control than the stereotaxy (75% vs 66.7%).

In selected patients, tailored procedures are required to achieve long-term tumor control and as well limit surgery-related morbidity. ORS could represent a safe and effective treatment option for cystic craniopharyngiomas, providing also reduced surgical related morbidity especially in recurrent lesions and in patients nonsuitable for radical surgery 4).



Bartels U, Laperriere N, Bouffet E, Drake J. Intracystic therapies for cystic craniopharyngioma in childhood. Front Endocrinol (Lausanne). 2012 Mar 27;3:39. doi: 10.3389/fendo.2012.00039. eCollection 2012. PubMed PMID: 22654864; PubMed Central PMCID: PMC3356106.

Zheng J, Fang Y, Cai BW, Zhang H, Liu W, Wu B, Xu JG, You C. Intracystic bleomycin for cystic craniopharyngiomas in children. Cochrane Database Syst Rev. 2014 Sep 19;9:CD008890. doi: 10.1002/14651858.CD008890.pub3. Review. PubMed PMID: 25233847.

Ansari SF, Moore RJ, Boaz JC, Fulkerson DH. Efficacy of phosphorus-32 brachytherapy without external-beam radiation for long-term tumor control in patients with craniopharyngioma. J Neurosurg Pediatr. 2016 Apr;17(4):439-45. doi: 10.3171/2015.8.PEDS15317. Epub 2015 Dec 18. PubMed PMID: 26684761.

Frio F, Solari D, Cavallo LM, Cappabianca P, Raverot G, Jouanneau E. OMMAYA RESERVOIR SYSTEM FOR THE TREATMENT OF CYSTIC CRANIOPHARYNGIOMAS: SURGICAL RESULTS IN A SERIES OF 11 ADULT PATIENTS AND REVIEW OF THE LITERATURE. World Neurosurg. 2019 Aug 7. pii: S1878-8750(19)32133-3. doi: 10.1016/j.wneu.2019.07.217. [Epub ahead of print] PubMed PMID: 31400528.
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