Brandon D. Liebelt

Incidence, Etiology and Outcomes of Hyponatremia after Transsphenoidal Surgery: Experience with 344 Consecutive Patients at a Single Tertiary Center

Hyponatremia is often seen after transsphenoidal surgery and is a source of considerable economic burden and patient-related morbidity and mortality. We performed a retrospective review of 344 patients who underwent transsphenoidal surgery at our institution between 2006 and 2012. Postoperative hyponatremia was seen in 18.0% of patients at a mean of 3.9 days postoperatively. Hyponatremia was most commonly mild (51.6%) and clinically asymptomatic (93.8%). SIADH was the primary cause of hyponatremia in the majority of cases (n = 44, 71.0%), followed by cerebral salt wasting (n = 15, 24.2%) and desmopressin over-administration (n = 3, 4.8%). The incidence of postoperative hyponatremia was significantly higher in patients with cardiac, renal and/or thyroid disease (p = 0.0034, Objective Risk (OR) = 2.60) and in female patients (p = 0.011, OR = 2.18) or patients undergoing post-operative cerebrospinal fluid drainage (p = 0.0006). Treatment with hypertonic saline (OR = −2.4, p = 0.10) and sodium chloride tablets (OR = −1.57, p = 0.45) was associated with a non-significant trend toward faster resolution of hyponatremia. The use of fluid restriction and diuretics should be de-emphasized in the treatment of post-transsphenoidal hyponatremia, as they have not been shown to significantly alter the time-course to the restoration of sodium balance.

Therapeutic targets in subependymoma

Subependymomas are usually treated with surgical resection; however, no standard, defined alternative medical therapy is recommended for patients who are not surgical candidates, owing to a paucity of molecular, immunological, and genetic characterization. To address this, an ex vivo functional analysis of the immune microenvironment in subependymoma was conducted, a subependymoma cytokine/chemokine microarray was constructed for the evaluation of operational immune and molecular pathways, and a subependymoma cell line was derived and used to test a variety of cytotoxic agents that target operational pathways identified in subependymoma. We found that immune effectors are detectable within the microenvironment of subependymoma; however, marked immune suppression is not observed. The subependymoma tissue microarrays demonstrated tumor expression of p53, MDM2, HIF-1α, topoisomerase II-β, p-STAT3, and nucleolin, but not EGFRvIII, EphA2, IL-13RA2, CMV, CTLA-4, FoxP3, PD-1, PD-L1, EGFR, PDGF-α, PDGF-β, PDGFR-α, PDGFR-β, PTEN, IGFBP2, PI3K, MDM4, IDH1, mTOR, or Jak2. A topoisomerase inhibitor (WP744, IC50=0.83 μM) and a p-STAT3/HIF-1α inhibitor (WP1066, IC50=3.15 μM) demonstrated a growth inhibition of the subependymoma cell proliferation. Cumulatively, these data suggest that those agents that interfere with oncogenes operational in subependymoma may have clinical impact.

Sellar Floor Reconstruction with the Medpor Implant Versus Autologous Bone After Transnasal Transsphenoidal Surgery: Outcome in 200 Consecutive Patients.

OBJECTIVE The Medpor porous polyethylene implant provides benefits to perform sellar floor reconstruction when indicated. This material has been used for cranioplasty and reconstruction of skull base defects and facial fractures. We present the most extensive use of this implant for sellar floor reconstruction and document the safety and benefits provided by this unique implant. METHODS The medical charts for 200 consecutive patients undergoing endonasal transsphenoidal surgery from April 2008 through December 2011 were reviewed. Material used for sellar floor reconstruction, pathologic diagnosis, immediate inpatient complications, and long-term complications were documented and analyzed. Outpatient follow-up was documented for a minimum of 1-year duration, extending in some patients up to 5 years. RESULTS Of the 200 consecutive patients, 136 received sellar floor cranioplasty using the Medpor implant. Postoperative complications included 6 complaints of sinus irritation or drainage, 1 postoperative cerebrospinal fluid leak requiring operative re-exploration, 1 event of tension pneumocephalus requiring operative decompression, 1 case of aseptic meningitis, 1 subdural hematoma, and 1 case of epistaxis. The incidence of these complications did not differ from the autologous nasal bone group in a statistically significant manner. CONCLUSIONS Sellar floor reconstruction remains an important part of transsphenoidal surgery to prevent postoperative complications. Various autologous and synthetic options are available to reconstruct the sellar floor, and the Medpor implant is a safe and effective option. The complication rate after surgery is equivalent to or less frequent than other methods of reconstruction and the implant is readily incorporated into host tissue after implantation, minimizing infectious risk.

Superior Petrosal Vein Sacrifice During Microvascular Decompression: Perioperative Complication Rates and Comparison with Venous Preservation

OBJECTIVE To investigate potential effect of sacrifice of the superior petrosal vein (SPV) on postoperative complications after microvascular decompression (MVD). METHODS Retrospective review of 98 consecutive patients undergoing MVD of cranial nerve V was performed. Frequency of division of the SPV during surgery was recorded, and postoperative complications and imaging were recorded and analyzed. In patients with complications, the specific anatomic variation of the superior petrosal venous complex was noted. RESULTS Of 98 patients undergoing MVD, 83 (84.7%) had sacrifice of the SPV at the time of surgery, 12 (12.2%) had the SPV preserved, and 3 (3.1%) were revision operations. Four patients (4.8%) had complications deemed to be attributable to venous insufficiency or congestion. These included sigmoid sinus thrombosis with coincident cerebellar hemorrhage, midbrain and pontine infarction, hemiparesis with midbrain and pontine edema, and facial paresis with ischemia in the middle cerebellar peduncle. None of the patients with preserved SPV were symptomatic or had imaging changes consistent with venous congestion. CONCLUSIONS Sacrifice of the SPV is often performed during MVD. This is associated with a complication rate that is significant in frequency and severity compared with preserving the vein. SPV sacrifice should be limited to cases where it is deemed absolutely necessary for successful cranial nerve decompression.

Epithelioid glioblastoma presenting as massive intracerebral hemorrhage: Case report and review of the literature

Background: Glioblastoma multiforme (GBM) is a malignant transformation of glial tissue, which presents as intradural, intraaxial lesions with heterogenous contrast enhancement and mass effect. Intratumoral hemorrhage is a common finding in GBM although it is frequently asymptomatic. Massive, symptomatic, intratumoral hemorrhage is uncommon and poses a diagnostic challenge. Case Description: Here we discuss a case of GBM, which initially presented as massive, symptomatic intracerebral hemorrhage with underlying mass. Due to size of the hemorrhage and poor neurological status the patient was taken to the operating room for evacuation of this hematoma. On pathology, the mass was found to be epithelioid glioblastoma. Conclusion: Identification and diagnosis of GBM is generally straightforward. In certain circumstances, the presentation of GBM can vary from the routine. The above case demonstrates how pitfalls in diagnosis can be avoided in order to initiate appropriate therapy.

The Anterior Subcallosal Approach to Third Ventricular and Suprasellar Lesions: Anatomical Description and Technical Note

BACKGROUND Surgical access to the third ventricle is challenging, given the depth of the operative field and close proximity of vital neural structures that must be traversed. For anterior third ventricular lesions, approach options include anterior transcallosal or transcortical, subfrontal, frontotemporal, or endonasal. The subcallosal approach, a translamina terminalis approach, is unique in that the surgical corridor is just below the corpus callosum, minimizes retraction and preserves corpus callosum integrity. Case examples are provided, and an anatomical study delineating the dimensions of the surgical corridor is performed. METHODS Two latex-injected cadaver heads were used to describe the subcallosal corridor. A magnetic resonance imaging scan was obtained and registered with neuronavigation for correlative anatomical illustration. Depth, dimensions, and cross-sectional area were measured for the subcommunicating and supracommunicating corridors. RESULTS The surgical depth for anterior transcallosal, subcallosal, and subfrontal approaches was 7.5 cm, 7.7 cm, and 7.6 cm respectively. The average corridor dimensions for the subcallosal approach were 14.75 × 6.63 mm compared with 8.88 × 5.38 mm for the subcommunicating corridor. Cross-sectional area of the subcommunicating corridor was 30.62 mm(2) compared with 80.42 mm(2) for supracommunicating. This was easily enlarged to 156.62 mm(2) with gentle retraction. CONCLUSIONS The anterior subcallosal approach is a safe approach for lesions of the third ventricle that avoids splitting the corpus callosum and resecting unnecessary brain and minimizes brain retraction. This corridor is superior to the traditional subfrontal approach in terms of working space and compares favorably to the anterior transcallosal approach without disrupting the corpus callosum.

Spinal Schwannoma and Meningioma Mimicking a Single Mass at the Craniocervical Junction Subsequent to Remote Radiation Therapy for Acne Vulgaris

BACKGROUND Schwannomas and meningiomas are relatively common tumors of the nervous system. They have been reported in the literature as existing concurrently as a single mass, but very rarely have they been shown to present at the craniocervical junction. CASE DESCRIPTION We present a rare and interesting case of a patient previously treated with radiation therapy for acne vulgaris and who presented to us with a concurrent schwannoma and meningioma of the craniocervical junction mimicking a single mass. CONCLUSIONS These tumors can be solitary or mixed masses, and are known to be associated with certain disease processes such as long-term sequelae of radiation therapy and neurofibromatosis type 2. The precise mechanism behind the formation of these tumors is unknown; however, molecular cues in the tumor microenvironment may play a role.

Herniated Discs of the Spine

The spine is divided into three main segments: the cervical spine, thoracic spine, and lumbar spine. There are seven cervical, twelve thoracic, and five lumbar vertebrate, and an intervertebral disc lies between each adjacent vertebrae. The sacrum and coccyx (pelvic area) do not contain discs. The vertebrae sit on top of one another like a stack of blocks with the intervertebral discs lying in between to function as a cushion and allow movement at each level. The spinal cord runs through the spinal canal, ending at L1. Spinal nerves exit the cord between each vertebrae. The spinal nerves in the lumbar spine come down from the spinal cord like a horse’s tail (cauda equina). Herniated discs can contact either the spinal cord or nerves and irritate them, producing symptoms of pain, numbness, or weakness.