Letter to the Editor: CSF leak in transsphenoidal surgery

TO THE EDITOR: We read with great interest the article by Mehta and Oldfield2 (Mehta GU, Oldfield EH: Prevention of intraoperative cerebrospinal fluid leaks by lumbar cerebrospinal fluid drainage during surgery for pituitary macroadenomas. J Neurosurg 116:1299–1303, June 2012). The authors investigated the role of lumbar drainage in transsphenoidal surgery, comparing the results of 114 operations without an intraoperative CSF drain to 44 cases in which a lumbar subarachnoid catheter was placed before surgery to drain CSF at the time of tumor removal. The intraoperative CSF leak rate was significantly lower when the spinal drain was used; the postoperative CSF leak rate was the same (5%) in the both groups. The authors’ conclusion is that intraoperative CSF drainage is useful, low risk, and obviates the need for sellar repair by lowering the intraoperative incidence of CSF leakage. The article is of great interest because it provides new data to add to the ongoing discussion on the use of CSF drainage in transsphenoidal surgery. Most advocates stress the usefulness of lowering intracranial pressure (ICP) to allow a definitive sealing of the subarachnoid space; opponents underline the possible risks of lumbar drainage and the lack of clear indications for it. The authors support its use because it lowers the incidence of intraoperative CSF leaks and therefore diminishes the need of sellar reconstruction. Examining the article’s data, though, this conclusion does not seem to be supported; furthermore, some data, which would add even more value to the paper, are missing. The most important clinical outcome reported by Mehta and Oldfield is that the rate of postoperative CSF leak does not decrease in the group with intraoperative drainage compared to the group without it; the rate was 5% in both groups. This might have two possible explanations: 1) the evidence of intraoperative CSF leaks in patients with lumbar drain is underestimated because of CSF diversion during surgery; 2) although the incidence of intraoperative CSF leaks is really lower, some other factors lead to postoperative leakage. The authors do not dwell on sellar packing, but they report that sellar reconstruction was performed less frequently when CSF diversion was used intraoperatively. Could this be the reason for the postoperative CSF leak? In Fig. 1 of their paper, the authors depict the physiopathogenesis of low-flow CSF leaks in transsphenoidal surgery: the removal of a macroadenoma leads to the descent of the suprasellar arachnoid, which then “weeps.” If sellar reconstruction is not performed in these cases, one could assume that a Valsalva maneuver (e.g., during extubation, coughing, or sneezing) might breach the arachnoid that is not supported. We could then interpret the reported data as support for sellar reconstruction rather than for CSF diversion (Fig. 1). This was indeed the case in our clinical practice: When we were not systematically using sellar packing with the endoscopic approach, we observed a postoperative CSF leak in a patient in whom no intraoperative CSF leakage occurred; postoperatively, the patient developed pneumonia, with persistent coughing, and subsequent evidence of a CSF leak. In other words, if the incidence of postoperative CSF leakage is the same regardless of whether we use an intra-

Letter to the Editor: Early noninvasive brain stimulation after severe TBI

In vitro and in vivo effect of human lactoferrin on glioblastoma growth

Human lactoferrin (HLF) is a natural protein with antitumor activity. The aim of this study was to investigate the effects of HLF alone and in combination with temozolomide (TMZ), a conventional chemotherapeutic, on human glioblastoma (GBM) cells.

Purely endoscopic resection of a choroid plexus papilloma of the third ventricle: case report

The authors report an illustrative case of a purely endoscopic surgical approach to successfully remove a solid choroid plexus papilloma of the third ventricle in an infant. A 10-week-old male infant first presented with transient episodes of forced downward gaze, divergent macrocephaly, a tense anterior fontanel, diastasis of the cranial sutures, and papilledema. Brain MRI revealed a small, multilobulated contrast-enhancing mass situated within the posterior third ventricle, with resultant obstructive hydrocephalus. A purely endoscopic removal of the tumor was performed through a single right frontal bur hole. Intraoperatively, a unique vascular tributary was recognized coming from the tela choroidea and was controlled with coagulation and sharp dissection. Postoperative MRI confirmed complete tumor removal, and the tumor was classified as a choroid plexus papilloma. There has been no evidence of tumor recurrence over 42 months of follow-up. With this case report the authors intended to show that endoscopic surgery can be an additional tool to consider when planning a choroid plexus tumor approach. It seems to be of particular interest in selected cases in which there are concerns about the patient's total blood volume, as in infants with potential hemorrhagic tumors and when it is possible to preoperatively identify a single vascular pedicle that can be approached early in the surgery.

Prophylactic nimodipine treatment for cochlear and facial nerve preservation after vestibular schwannoma surgery: a randomized multicenter Phase III trial

A pilot study of prophylactic nimodipine and hydroxyethyl starch treatment showed a beneficial effect on facial and cochlear nerve preservation following vestibular schwannoma (VS) surgery. A prospective Phase III trial was undertaken to confirm these results.

Parkinson’s disease outcomes after intraoperative CT-guided “asleep” deep brain stimulation in the globus pallidus internus

Recent studies show that deep brain stimulation can be performed safely and accurately without microelectrode recording ortest stimulation but with the patient under general anesthesia. The procedure couples techniques for direct anatomical targeting on MRI with intraoperative imaging to verify stereotactic accuracy. However, few authors have examined the clinical outcomes of Parkinson's disease (PD) patients after this procedure. The purpose of this study was to evaluate PD outcomes following "asleep" deep brain stimulation in the globus pallidus internus (GPi).

Rescue N-butyl-2 cyanoacrylate embolectomy using a Solitaire FR device after venous glue migration during arteriovenous malformation embolization: technical note

One of the procedural risks in arteriovenous malformation (AVM) embolization is possible migration of the embolic agent into the venous drainage with an incomplete nidus occlusion, which may lead to severe hemorrhagic complications. This report presents the case of a 29-year-old man who presented with a deep intraparenchymal hematoma on the left side secondary to the spontaneous rupture of a claustral AVM. Upon resorption of the hematoma, the patient underwent an initial therapeutic session of N-butyl-2 cyanoacrylate endovascular embolization, with the purpose of reducing the AVM volume and flow before performing Gamma Knife radiosurgery. After glue injection into one of the arterial feeders, the control angiography showed a partial migration of the glue cast into the straight sinus, with most of the nidus still visible. Because of the bleeding risk due to possible venous hypertension, it was decided to try to retrieve the glue from the vein by using a stent retriever via jugular access. This maneuver allowed a nearly complete removal of the glue cast, thereby restoring normal venous flow drainage. The patient showed no clinical worsening after the procedure. To the authors' knowledge, this is the first report of the use of the Solitaire FR device as a rescue glue retriever. This method should be considered by physicians in cases of unintended glue migration into the venous circulation during AVM embolization.

The far-lateral approach: destruction of the condyle does not necessarily result in clinically evident craniovertebral junction instability

OBJECT Far-lateral or extreme-lateral approaches to the skull base allow access to the lateral and anterior portion of the lower posterior fossa and foramen magnum. These approaches include a certain extent of resection of the condyle, which potentially results in craniocervical junction instability. However, it is debated what extent of condyle resection is safe and at what extent of condyle resection an occipitocervical fusion should be recommended. The authors reviewed cases of condyle resection/destruction with regard to necessity of occipitocervical fusion. METHODS The authors conducted a retrospective analysis of all patients in whom a far- or extreme-lateral approach including condyle resection of various extents was performed between January 2007 and December 2014. RESULTS Twenty-one consecutive patients who had undergone a unilateral far- or extreme-lateral approach including condyle resection were identified. There were 10 male and 11 female patients with a median age of 61 years (range 22-83 years). The extent of condyle resection was 25% or less in 15 cases, 50% in 1 case, and greater than 75% in 5 cases. None of the patients who underwent condyle resection of 50% or less was placed in a collar postoperatively or developed neck pain. Two of the patients with condyle resection of greater than 75% were placed in a semirigid collar for a period of 3 months postoperatively and remained free of pain after this period. At last follow-up none of the cases showed any clear sign of radiological or clinical instability. CONCLUSIONS The unilateral resection or destruction of the condyle does not necessarily result in craniocervical instability. No evident instability was encountered even in the 5 patients who underwent removal of more than 75% of the condyle. The far- or extreme-lateral approach may be safer than generally accepted with regard to craniocervical instability as generally considered and may not compel fusion in all cases with condylar resection of more than 75%.

Intraoperative high-resolution ultrasound and contrast-enhanced ultrasound of peripheral nerve tumors and tumorlike lesions

The diagnostic workup and surgical therapy for peripheral nerve tumors and tumorlike lesions are challenging. Magnetic resonance imaging is the standard diagnostic tool in the preoperative workup. However, even with advanced pulse sequences such as diffusion tensor imaging for MR neurography, the ability to differentiate tumor entities based on histological features remains limited. In particular, rare tumor entities different from schwannomas and neurofibromas are difficult to anticipate before surgical exploration and histological confirmation. High-resolution ultrasound (HRU) has become another important tool in the preoperative evaluation of peripheral nerves. Ongoing software and technical developments with transducers of up to 17-18 MHz enable high spatial resolution with tissue-differentiating properties. Unfortunately, high-frequency ultrasound provides low tissue penetration. The authors developed a setting in which intraoperative HRU was used and in which the direct sterile contact between the ultrasound transducer and the surgically exposed nerve pathology was enabled to increase structural resolution and contrast. In a case-guided fashion, the authors report the sonographic characteristics of rare tumor entities shown by intraoperative HRU and contrast-enhanced ultrasound.

Oral Presentations 2014 AANS Annual Scientific Meeting San Francisco, California • April 5–9, 2014Published online June 1, 2015; DOI: 10.3171/2015.6.JNS.AANS2014abstracts