This Week in Neurosurgery — Sep 16, 2026

Welcome to This Week in Neurosurgery. This week we're covering 10 notable papers spanning cerebrospinal fluid diversion and hydrocephalus, cerebrovascular and aneurysm strategy, degenerative spine surgery, and a cluster of evidence-quality questions running from thromboprophylaxis after head injury to how our guidelines themselves get written. Let's dive in.

We'll start with cerebrospinal fluid disorders, where a major review and a feasibility study approach the same problem from opposite ends. JAMA published a comprehensive review of idiopathic normal pressure hydrocephalus by Maroufi and colleagues that is worth reading even if you shunt these patients weekly [1]. The headline epidemiology is a reminder of how much disease is out there — roughly one to four percent of adults over 65, rising to six to eight percent of those over 80. Gait disturbance is the earliest and most consistent feature, present in the large majority of patients, with urinary dysfunction and an attentional, processing-speed pattern of cognitive impairment following. The practical emphasis is on selection rather than diagnosis: ventricular enlargement on magnetic resonance imaging is necessary but does not reliably predict who will respond to surgery. The review endorses large-volume lumbar puncture with removal of 30 to 50 millilitres of cerebrospinal fluid, assessed by objective gait measures within hours, and reserves extended lumbar drainage of 200 to 300 millilitres over several days for patients with high clinical suspicion but a negative or equivocal tap. The outcome figures are encouraging — roughly three quarters of shunted patients gain gait velocity, with cognitive and urinary improvement in around half to two thirds — but overdrainage or underdrainage affects up to three in ten, and shunt malfunction around one in six. Early referral matters, because shorter symptom duration predicts better outcome.

On the endovascular side of cerebrospinal fluid diversion, Neurosurgery published a morphometric candidacy study from Vajipayajula and colleagues looking at whether patients with idiopathic intracranial hypertension are anatomically suitable for transvenous endovascular shunting with the eShunt device, which is deployed from the inferior petrosal sinus into the cerebellopontine angle cistern [2]. In 84 patients imaged after venous sinus stenting, feasibility ranged from about 43 percent under the most stringent cistern-depth criterion to just over four fifths of patients under the most permissive one. One finding is immediately clinically usable: patients with cerebellar tonsillar descent had significantly smaller cerebellopontine angle cisterns and were essentially excluded. This is anatomy, not outcomes — no device was implanted — but it tells you that a substantial share of your stenting population could plausibly be eligible if trials support the technology.

Turning to aneurysm surgery, two papers argue that anatomy should drive strategy rather than habit. In Operative Neurosurgery, Chen and colleagues report 46 posterior inferior cerebellar artery aneurysms treated endovascularly with a segment-based algorithm — proximal lesions coiled or stent-assisted coiled with parent artery preservation in every case, while two thirds of distal aneurysms were managed with deliberate parent artery occlusion [3]. Most of these were ruptured. Complete occlusion immediately was achieved in about two thirds and rose to nearly all aneurysms at follow-up with no recurrences, and about three quarters of patients reached a modified Rankin score of zero to two. The cost is real, though: intraprocedural ischaemic events in roughly one in eleven patients, including one fatal in-stent thrombosis, and every patient with postprocedural infarction had an unfavourable outcome.

Mirroring that logic on the open side, World Neurosurgery carried a study from Mohsen and colleagues proposing a three-dimensional morphometric framework for posteriorly directed anterior communicating artery aneurysms [4]. Across 21 patients, they used the inter-A2 ratio, the coronal alignment of the A2 segments, and aneurysm height to choose between pterional and interhemispheric routes. The pterional approach was their default, used in 15 cases, because it lets the clip sit parallel to the anterior communicating complex; the interhemispheric route was reserved for high-riding aneurysms, a small inter-A2 ratio, or A2 segments lying in the same coronal plane. Complete occlusion was achieved in 18 of 21, with three small stable dog-ear residuals. It's a small single-centre series, but the message — that two-dimensional projection classification underdescribes the obstacles you'll actually meet — is a sound one.

In degenerative spine, two World Neurosurgery papers speak to the promise and the hazard of minimally invasive approaches. Centofanti and colleagues retrospectively compared 419 patients undergoing one or two-level lumbar fusion at a single academic centre, and found that reoperation for adjacent segment disease was roughly halved with minimally invasive fusion compared with open surgery — about nine percent versus nineteen percent over a mean follow-up near three years [5]. In the smaller subset of just over a hundred patients with two-year patient-reported outcomes, the minimally invasive group also reported better quality of life and substantially less disability, with Oswestry scores around 13 compared with 25. This is retrospective and the outcomes subset is small and likely selected, so treat it as supportive rather than definitive — but it is consistent with the facet-preservation rationale.

The counterweight comes from Lee and colleagues, who reviewed 1,011 oblique lumbar interbody fusions and identified nine cases, just under one percent, of contralateral nerve root injury [6]. The mechanisms are instructive: cage malposition in three, remnant disc rupture in four, and — newly described — facet synovial rupture in two patients with marked facet hypertrophy and subluxation. These presented with severe pain and motor deficits, and some required reoperation. The takeaway for the operating surgeon is to respect intraoperative cage margins, and to keep contralateral pathology in mind when a patient wakes with new radicular deficit on the side you weren't working on.

Finally, a group of papers about the strength of our evidence. The one most likely to change an order set comes from Neurosurgery, where Raccagni and colleagues pooled twelve retrospective studies comparing low-molecular-weight heparin with unfractionated heparin for thromboprophylaxis in adult traumatic brain injury [7]. Low-molecular-weight heparin was associated with roughly a 40 percent lower risk of venous thromboembolism, with consistent reductions in deep vein thrombosis and pulmonary embolism. Critically, the bleeding signal went the same direction rather than the opposite one — intracranial haemorrhage progression was about 30 percent lower, and delayed craniectomy and in-hospital mortality were also lower, although certainty for those last two outcomes was very low. Certainty was moderate for venous thromboembolism and pulmonary embolism. All twelve studies were retrospective, so confounding by indication is the obvious worry — sicker, higher-bleeding-risk patients may well have been given unfractionated heparin — but nothing here supports a bleeding penalty for low-molecular-weight heparin in appropriately selected patients.

Also in Neurosurgery, Mikkelsen and colleagues systematically reviewed asleep versus awake subthalamic deep brain stimulation for Parkinson's disease and found no significant difference in levodopa equivalent dose reduction or in quality of life on the Parkinson's Disease Questionnaire [8]. That quantitative comparison rests on only two randomised trials, and the authors argue that asleep and awake each cover a heterogeneous range of techniques, so this is an absence of demonstrated difference rather than proof of equivalence. On tumours, World Neurosurgery published a 92-patient Vancouver series of spheno-orbital meningiomas from Wang and colleagues, in which adjuvant radiotherapy was independently associated with better progression-free survival — five-year progression-free survival around 81 percent versus 65 percent — despite being given to tumours with more vascular encasement, optic apparatus involvement and cavernous sinus infiltration [9]. Median overall survival exceeded fifteen years, underlining the need for genuinely long-term surveillance. And rounding out the theme, Neurosurgery published an update on the Congress of Neurological Surgeons guidelines methodology from Koutsouras and colleagues, benchmarked against other specialty societies, adding patient representatives to task forces, a second librarian-led literature search before publication, annual surveillance of published guidelines, and a rapid-response pathway for high-impact new evidence [10].

If you only have time for one paper this week, make it the traumatic brain injury thromboprophylaxis meta-analysis in Neurosurgery [7]. It addresses a decision you make on almost every head injury admission, and it points consistently in one direction for both clot and bleeding outcomes.

Here are the key takeaways from this week in Neurosurgery. Low-molecular-weight heparin outperformed unfractionated heparin on both thrombotic and haemorrhagic outcomes after traumatic brain injury, though the evidence is entirely retrospective. In suspected normal pressure hydrocephalus, imaging does not predict shunt response — objective gait testing after high-volume cerebrospinal fluid removal does, and earlier referral means better outcomes. Anatomy should dictate aneurysm strategy, whether that means parent artery occlusion for distal posterior inferior cerebellar artery lesions or choosing an interhemispheric route for a high-riding anterior communicating aneurysm. Minimally invasive lumbar fusion was associated with about half the rate of reoperation for adjacent segment disease, but oblique interbody fusion carries a small, specific risk of contralateral root injury with three identifiable mechanisms. And asleep versus awake subthalamic stimulation still shows no demonstrated difference in efficacy or quality of life — on evidence thin enough that the question remains genuinely open.

That's your roundup for This Week in Neurosurgery. The full transcript and references are available on the episode page in your AudioScholar library. This is an AI-curated summary — for clinical decisions, always consult primary sources and current guidelines. See you next week.

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This is an automated summary generated by artificial intelligence, which can make mistakes. Always review the original source materials.