Acute Spontaneous Paradoxical Herniation After Large Cerebral Meningioma Resection and Decompressive Craniectomy: A Case Report and Systematic Review of the Literature

Abstract

BACKGROUND AND IMPORTANCE:

Paradoxical herniation (PH) is a rare but life-threatening complication after decompressive hemicraniectomy (DHC) performed to treat refractory intracranial hypertension. Although most cases occur subacutely or after cerebrospinal fluid (CSF) diversion, acute presentations without preceding CSF manipulation are uncommon and may be underrecognized.

CLINICAL PRESENTATION:

We report the case of a 45-year-old woman who developed acute PH after undergoing DHC for severe vasogenic edema after resection of a parieto-occipital meningioma. After initial postoperative neurological improvement, she experienced rapid neurological deterioration. Imaging demonstrated cerebellar tonsillar herniation and brain shift away from the craniectomy site, consistent with PH. Trendelenburg positioning resulted in prompt neurological improvement, confirming the diagnosis. We additionally performed a systematic review of reported cases of PH after tumor resection.

CONCLUSION:

PH should be considered in patients with fluctuating or worsening neurological status after DHC, even in the absence of prior CSF diversion. Early recognition is critical, as standard intracranial pressure-lowering therapies may exacerbate herniation. Management requires immediate cessation of such therapies, initiation of intracranial pressure-augmenting measures, and prompt cranioplasty as definitive treatment.

ABBREVIATIONS:

DHC

decompressive hemicraniectomy

PH

paradoxical herniation.

A rare but serious complication of decompressive hemicraniectomy (DHC) is paradoxical herniation (PH), defined as downward herniation of supratentorial contents with brainstem compression and neurological deterioration.^1,2 PH represents the most severe form of the syndrome of the trephined or sunken skin flap syndrome.³

After DHC, removal of the cranial vault converts the intracranial compartment to an open system, allowing atmospheric pressure to act directly on the brain.^4,5 This predisposes to inward deformation and downward herniation. PH may present with a concave scalp deformity and symptoms including headache, focal deficits, cognitive impairment and altered level of consciousness.⁴ These findings likely reflect disrupted cerebrospinal fluid (CSF) dynamics and atmospheric pressure transmission through the cranial defect.^4,5

PH commonly occurs in the subacute or chronic period and is frequently precipitated by CSF diversion procedures.⁶ Acute presentations are uncommon and may complicate diagnosis.^7-9 We report a case of acute spontaneous PH after DHC performed for cerebral edema after resection of a parieto-occipital meningioma. This case underscores that PH can occur abruptly after DHC without preceding CSF diversion. Prompt diagnosis is critical, as standard intracranial pressure (ICP)-lowering therapies may worsen herniation. A systematic review of reported cases of PH after tumor resection is provided.

CLINICAL PRESENTATION

A 45-year-old woman presented with headache without focal neurological deficits. MRI showed a large right-sided parieto-occipital extra-axial mass with vasogenic edema and subfalcine and transtentorial herniation (Figure 1A). Neurological examination was normal. She underwent a craniotomy for maximal safe resection and duroplasty. A small anteromedial remnant was intentionally left because of infiltrative features (Figure 1B). Pathology confirmed a World Health Organization grade 2 atypical meningioma. Her complex clinical course is summarized in Figure 2.

FIGURE 1.

A, Preoperative MRI demonstrates a large right-sided extra-axial dural-based parieto-occipital lesion with maximal measurements of 6.7 × 4.5 cm in the axial plane, exerting significant mass effect with midline shift of 1.2 cm. B, Postoperative MRI demonstrating gross total resection.

FIGURE 2.

Descriptive timeline of clinical events and associated radiographic findings. DHC, decompressive hemicraniectomy; POD, postoperative day.

On postoperative day (POD) 3, she developed acute confusion. Imaging demonstrated worsening edema, increased midline shift, and a thin subdural collection (Figure 3). Rapid neurological deterioration ensued, progressing to flexion posturing, no eye opening, and incoherent sounds. Pupils became 3mm and nonreactive bilaterally. Emergent right-sided DHC was performed that day. Immediate post-DHC imaging showed improved mass effect and reduced midline shift (Figure 4). Over subsequent days, her level of consciousness fluctuated, and pupils became asymmetric. Computed tomography performed POD5 from her DHC demonstrated recurrent midline shift with tonsillar herniation (Figure 5A and 5B), prompting the clinical diagnosis of elevated ICP. Electroencephalography, MRI, and magnetic resonance venography showed no evidence of seizure, infarction, or venous thrombosis (Figure 5C and 5D). Despite hyperosmolar therapy, her neurological status continued to decline.

FIGURE 3.

Computed tomography head conducted on postoperative day 3 shows increasing mass effect from the surgical cavity and a right frontal convexity subdural collection causing a 1.4 cm midline shift.

FIGURE 4.

Status post-decompressive hemicraniectomy showing improved mass effect and reduction of midline shift.

FIGURE 5.

A, CT head performed postoperative day 5 post-DHC demonstrating tonsillar herniation. B, CT imaging performed on postoperative day 5 from DHC demonstrating worsening midline shift and mass effect, as well as improvement in pneumocephalus compared with earlier CT performed post-DHC. C, Unremarkable magnetic resonance venogram performed after post decompressive hemicraniectomy deterioration. Cortical or sinus venous thrombosis was high on our differential diagnosis at that time. D, Expected postoperative diffusion-weighted imaging changes were noted on MRI. No additional changes were noted, making cortical venous or arterial infarct less likely. CT, computed tomography; DHC, decompressive hemicraniectomy.

PH was suspected on POD7 from her DHC despite a normal appearing flap, and Trendelenburg positioning produced neurological improvement within 2 hours, confirming the diagnosis. Urgent right-sided cranioplasty resulted in neurological recovery and resolution of tonsillar herniation (Figure 6A and 6B). At discharge (6 weeks postoperatively), midline shift was significantly reduced (Figure 7), and the patient was ambulatory and independent. At 6 months, she had returned to baseline function and resumed work. At 5 years, she remains neurologically intact with no tumor recurrence.

FIGURE 6.

A, Comparison of mass effect and tonsil descent pre- and postcranioplasty. Before cranioplasty, there is crowding of the posterior fossa. B, Postcranioplasty, there is improvement in overall mass effect and decreased crowding of the posterior fossa with reduced tonsillar descent.

FIGURE 7.

Postoperative week 6 from cranioplasty, a computed tomography scan of the brain showed near-resolution of the midline shift.

This case report was conducted in accordance with institutional policy. Institutional Research Ethics Board approval was not required for this retrospective, deidentified case report. Written informed consent was not obtained per institutional policy.

DISCUSSION

PH is a rare neurosurgical emergency postulated to result from an imbalance between extracranial and ICPs after DHC.⁵ Removal of the cranial vault converts the intracranial compartment to an open system, permitting atmospheric pressure to act directly on the brain and predisposing to downward herniation.^4-6 In this setting, reduction in CSF pressure because of altered CSF dynamics may further accentuate the extracranial-intracranial gradient.^7-12 This mechanism is consistent with the characteristic concave scalp deformity. In addition, reductions in cerebral blood flow (CBF) have been demonstrated after DHC, which may further lower intracranial blood volume and ICP, exacerbating the extracranial-ICP gradient.^13,14 Restoration of CBF after cranioplasty parallels clinical recovery, which may support its contributory role.^13,14

To contextualize this presentation, we conducted a systematic review in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.¹⁵ MEDLINE, EMBASE, Cochrane CENTRAL, and Web of Science were searched using terms related to PH, syndrome of the trephined, and intracranial tumors (Supplemental Digital Content 1, Search Strategy, http://links.lww.com/NS9/A114). Studies describing PH after tumor resection were included. Screening and data extraction were performed independently by 2 reviewers (C.V., B.S.K.), and methodological quality was assessed using Murad tool for case reports/series¹⁶ and Risk Of Bias In Non-randomized Studies of Interventions for observational studies.¹⁷

Twelve articles met inclusion criteria, comprising 86 patients (Supplemental Digital Content 2, Figure 1, http://links.lww.com/NS9/A115; Table).^12,18-28 Most tumors were meningioma,^12,18-28 with isolated cases of craniopharyngioma,¹² oligodendroglioma,¹² or metastasis.²⁸ Indications for craniectomy included vasogenic edema,^18,25 osseous tumor infiltration,²⁴ venous infarction,²³ and postoperative infection.²⁵ CSF diversion preceded neurological deterioration in half of studies (6/12).^{12,18,20,21,25,28} Time to deterioration ranged from 1 day to several years.^{18-21,23-25,28} Temporizing treatments included Trendelenburg positioning,^21,23 supine positioning,^18,22 intravenous fluids,¹⁸ and discontinuation of ICP-lowering or CSF diversion therapies. Cranioplasty was the definitive treatment in nearly all cases.^12,18-28

TABLE.

Previously Reported Cases of Paradoxical Herniation After Craniectomy Procedures Performed in the Setting of Tumor Resection

Authors	Year	Age (y)	Sex	Tumor type	Location	Treatment of initial presentation	CSF diversion/CSF leak	Time to deterioration from index surgery	Treatment of paradoxical herniation	Outcome
Amaral et al18	2024	48	F	Meningioma	Left fronto-orbital	Tumor resection followed by craniectomy because of postoperative swelling with midline shift	LD PO to reduce risk of CSF leak	3 d	Supine position, IVF, cranioplasty a 1 mo PO	Improved, discharged to rehabilitation at 34 d PO
Santander et al19	2022	Mean 51.7	53% F	1/17 reported cases was tumor etiology	NR	NR	NR	Mean 19 d	Cranioplasty	94.11% of patients improved PO
Sahoo et al20	2021	37	F	Meningioma	Parasagittal	Resection of tumor with craniectomy	Thecoperitoneal shunt for bulging brain through craniectomy defect	48 h	Cranioplasty	Deceased from PO infection and sepsis
Tarr et al21	2020	38.4 ± 12.3	40% F	32% meningioma	NR	NR	10% had VP shunt	4.5 ± 1.1 mo (2.4-7.2)	Trendelenburg, cranioplasty	95% improvement, 70% complete resolution of symptoms
Narro-Donate et al22	2015	56	F	Meningioma	Olfactory groove	Resection of tumor with craniectomy	NR	NR	Supine position, cranioplasty	NR
Ziyal et al23	2005	70	M	Meningioma	Parasagittal	Resection of tumor complicated by bilateral venous infarction requiring craniectomy	NR	1 mo	Trendelenburg	Improved
Kumar et al24	2004	45	F	Meningioma	Right frontoparietal	Resection with craniectomy because of tumor infiltration	NR	37 d	Cranioplasty	Improved
Schiffer et al25	1997	44	M	Meningioma	Parietal	Resection with craniectomy because of brain edema	NR
		44	F	Meningioma	Right temporoparietal	Resection with craniectomy	NR	7 y	Cranioplasty	Improved
		68	F	Meningioma	Right frontoparietal meningioma	Resection with craniotomy, subsequent craniectomy for infection	Serial LPs	4 mo	Cranioplasty	Improved, mild residual deficits PO
		51	M	Meningioma	Right frontotemporal	Resection with craniotomy, subsequent craniectomy for infection	VP shunt	NR	Cranioplasty and VP shunt	Improved to preoperative baseline
		47	F	Meningioma	Left parasagittal	Resection with craniectomy	NR	NR	Cranioplasty	Improved with residual deficits
Fodstad et al26	1984	Mean 47 (range 22-74)	42.5% F	32.5% meningioma	NR	NR	NR	NR	Cranioplasty 3-51 mo, mean 15 mo	NR
Stula et al27	1982	Range 18-72	NR	11.1% meningioma	Parafalcine	NR	NR	NR	Cranioplasty	Improved
Yamaura et al12	1977	Mean 40 (range 5-69)	42.4% F	Meningioma	NR	Resection with craniectomy	NR	NR	Cranioplasty 12-18 mo	Stable PO (no deficits)
				Meningioma	NR	Resection with craniectomy	NR	NR	Cranioplasty 12-18 mo	Improved
				Meningioma	NR	Resection with craniectomy	NR	NR	Cranioplasty 12-18 mo	Stable PO (minimal deficit)
				Meningioma	NR	Resection with craniectomy	NR	NR	Cranioplasty 12-18 mo	Improved
				Meningioma	NR	Resection with craniectomy	NR	NR	Cranioplasty 12-18 mo	Improved
				Meningioma	NR	Resection with craniectomy	NR	NR	Cranioplasty 12-18 mo	Improved
				Meningioma	NR	Resection with craniectomy	NR	NR	Cranioplasty 12-18 mo	Improved
				Meningioma	NR	Resection with craniectomy	NR	NR	Cranioplasty 12-18 mo	Improved
				Meningioma	NR	Resection with craniectomy	NR	NR	Cranioplasty 12-18 mo	Improved
				Meningioma	NR	Resection with craniectomy	NR	NR	Cranioplasty 12-18 mo	Stable PO (moderate deficit)
				Meningioma	NR	Resection with craniectomy	NR	NR	Cranioplasty 12-18 mo	Stable PO (severe deficit)
				Craniopharyngioma	NR	Resection with craniectomy	NR	NR	Cranioplasty 12-18 mo	Stable PO (no deficit)
				Oligodendroglioma	NR	Resection with craniectomy	NR	NR	Cranioplasty 12-18 mo	Improved
Guido et al28	1976	70	M	Meningioma	NR	Resection	LD preoperatively	3 d	Supine position, epidural blood patch	Improved
		47	M	Metastasis	NR	Resection	LD preoperatively	12-24 h	Epidural blood patch	Return to baseline

CSF, cerebrospinal fluid; F, female; IVF, intravenous fluids; LD, lumbar drain; LP, lumbar puncture; M, male; NR, not reported; PO, postoperatively; VP shunt, ventriculoperitoneal shunt.

Risk-of-bias assessments revealed substantial methodological limitations (Supplemental Digital Content 2, Figures 2 and 3, http://links.lww.com/NS9/A115). Case reports and series^{18,20,22-25,27,28} demonstrated low risk of bias across domains of selection, ascertainment, and reporting, with occasional uncertainty in causality.¹⁶ Observational studies^12,19,21,26 exhibited serious to critical risk of bias across multiple domains, including confounding, participant selection, deviations from intended interventions, missing data, and outcome measurement.¹⁷ This underscores the rarity of tumor-associated PH and the absence of high-level evidence to guide management.

Our case demonstrates several distinguishing features. As mentioned, PH commonly occurs in the subacute or chronic period after craniectomy,^12,18-28 and is frequently precipitated by CSF diversion procedures, including lumbar puncture, lumbar drainage, or ventriculoperitoneal shunting.^{12,18,20,21,25,28} Although early presentations within 14 days have been reported, these cases were uniformly associated with CSF diversion.^18,20,28 By contrast, our patient developed acute PH within days of DHC in the absence of preceding CSF manipulation. This presentation initially mimicked worsening cerebral edema, and ICP-lowering therapies were administered. In such cases, consideration of ICP monitoring may be helpful in raising suspicion for PH. In this case, continued neurological decline despite hyperosmolar treatment prompted reconsideration of the diagnosis. Rapid improvement with the Trendelenburg positioning supported PH, and urgent cranioplasty resulted in immediate neurological recovery.

We suspect that alterations in CSF and CBF dynamics related to the resection of a large atypical meningioma played a central role. Reduced CBF has been observed preoperatively in patients with large meningiomas,²⁹ and we hypothesize that these changes were amplified after DHC, further destabilizing ICP homeostasis. The absence of clinical or radiographic features of intracranial hypotension preoperatively made an occult CSF leak unlikely.

Recognition of PH is critical because therapies aimed at lowering ICP may exacerbate herniation. Once PH is suspected, therapies aimed at lowering ICP must be halted. Instead, measures to raise ICP, such as Trendelenburg positioning and intravenous fluids, should be implemented. Clinical improvement with temporary measures supports the diagnosis. Epidural blood patching may be considered when a CSF leak is suspected.^28,30-33 Definitive management requires cranioplasty, which restores the cranial vault, mitigates extracranial pressure effects, and reestablishes normal CBF and CSF dynamics.^4,6,9,34-36

CONCLUSION

PH is a rare but life-threatening condition after DHC. Although typically subacute or associated with CSF diversion, acute presentations without prior CSF manipulation can occur. PH should be considered in patients with fluctuating neurological status after DHC, as delayed recognition may be fatal. Management requires immediate cessation of ICP-lowering therapies and initiation of ICP-augmenting measures. Definitive treatment is prompt cranioplasty.

Supplementary Material

neuopen-7-e000250-s001.docx ^{(15.8KB, docx)}

neuopen-7-e000250-s002.pdf ^{(775.4KB, pdf)}

Funding

This study did not receive any funding or financial support.

Disclosures

Michael M. H. Yang received funding from Stryker Canada. Mark G. Hamilton is a consultant to Integra LifeSciences and has received honoraria and travel support for educational activities, he is a consultant to Grasshopper Health. The other authors have no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article.

Supplemental Digital Content

Supplemental Digital Content 1: Appendix A (paradoxical herniation search strategy).

Supplemental Digital Content 2: Figure 1. Prisma-P flow diagram for systematic reviews illustrating study identification, screening, eligibility and inclusion for the systematic review of paradoxical herniation after intracranial tumor resection. Figure 2. Risk-of-bias assessment for included case reports and case series using the Murad et al tool, evaluating selection, ascertainment, causality, and reporting domains. Most studies demonstrated low risk of bias, with occasional uncertainty in causality. Figure 3. Risk-of-bias assessment for observational studies using the ROBINS-I tool. Included studies demonstrated serious to critical risk of bias across multiple domains including confounding, participant selection, missing data and outcome measurement.