Arachnoid cyst presenting as a neurosurgical emergency: a case report

Introduction

Arachnoid cysts are intra-arachnoid lesions filled with cerebrospinal fluid. They account for ~1% of all intracranial mass lesions and are non-neoplastic collections of cerebrospinal fluid within an anomalous arachnoid enclosure.

Case presentation

The authors report a 35-year-old Arabian male who presented to the ER with a history of sudden loss of consciousness, anisocoria, and right hemiparesis. Contrast tomography showed a large frontoparietotemporal cyst (7.7×5.8×5.4) with uncal herniation and a midline shift of 12 mm. An emergency left FTP craniotomy with an excision of the cyst was performed.

Discussion

Arachnoid cysts can be categorized as primary or secondary, arising congenitally or due to factors like trauma, infection, or neoplasia. It can rupture, leading to internal bleeding, causing symptoms such as headaches, seizures, and neurological decline. Rapid diagnosis is vital, with cranial computed tomography scans preferred for emergencies. Treatment options include surgical intervention like craniotomy, fenestration, or cyst peritoneal shunts. For uncal herniation, surgery can be successful and results depends on the amount of herniation.

Conclusion

Although benign, the arachnoid cysts led to uncal herniation when they become 'tension' cysts. A high level of suspicion is crucial for early recognition of the condition. Timely intervention has shown positive recovery outcomes.

Is decompressive craniectomy necessary in malignant posterior reversible encephalopathy syndrome with brain edema caused uncal herniation? A case report of reversible coma without surgical decompression

BACKGROUND

Posterior reversible encephalopathy syndrome (PRES) is considered a benign entity and is usually reversible with only medical management, but persistent neurologic deficits and disability or death can occur without adequate treatment. Favorable outcomes have been associated with surgical decompression in malignant-type PRES in which hemorrhagic transformation or brain stem compression has developed.

CASE DESCRIPTION

Here we report a case of malignant PRES in a 61-year-old female of Asian descent in which the disease rapidly progressed to coma and a near-fatal condition with uncal herniation caused by severe brain edema; however, this patient achieved a dramatic recovery without surgical decompression.

CONCLUSION

After reviewing previous reports regarding malignant PRES, we propose that hemorrhagic transformation is a crucial indicator for surgical decompression and an important prognostic factor in malignant PRES.

Near-Infrared Spectroscopy-Guided Hyperventilation for Transient Intracranial Pressure Control during Anesthesia Induction in a Patient with Impending Uncal Herniation

Near-infrared spectroscopy (NIRS) is known to determine the adequacy of regional cerebral oxygen supply. NIRS values during anesthetic induction depends upon various factors such as anesthetic agents, inspired oxygen fraction, blood carbon dioxide levels and systemic blood pressure. Also high intracranial pressure (ICP) can lead to reduced NIRS values, secondary to increased cerebral vascular resistance induced decrease in cerebral blood flow. However optimal hyperventilation instituted as a bridge to definitive ICP management is difficult to ascertain as hypocapnia due to poorly titrated hyperventilation can potentially worsen ICP. Here we describe a novel application of NIRS-guided hyperventilation during anesthesia induction in a brain tumor patient with raised ICP features and impending uncal herniation as suggested by computed tomography (CT) scan, with ipsilateral baseline reduced NIRS values. These ipsilateral NIRS values further reduced significantly during anesthesia induction even before profound bradycardia occurred, which promptly improved to baseline following hyperventilation.

Delayed Hemiparkinsonism Associated with Kernohan's Notch in a Patient with a Ruptured Arteriovenous Malformation

A 24-year-old female patient was admitted for a right frontal intracranial hematoma with an uncal herniation due to a ruptured arteriovenous malformation and therefore underwent emergency surgery. Neuroimaging revealed left-sided midbrain notching against the tentorium, indicating Kernohan's notch phenomenon. She denied experiencing any short-term neurological deficits but right-sided delayed hemiparkinsonism developed 18 months later. Dopamine transporter tracer uptake was severely reduced in the left striatum, suggesting nigrostriatal degeneration secondary to Kernohan's notch. Uncal herniations are potentially fatal, but surgery can save the patient's life and improve the functional outcomes. Clinicians should therefore be aware of delayed hemiparkinsonism as a rare complication of Kernohan's notch phenomenon.

Uncal herniation in a fully conscious patient-The sliding uncus syndrome

Uncal herniation is accompanied by a decreased level of consciousness. We describe a patient who remained fully alert despite the uncal herniation. The computed tomography (CT) scans allowed us to visualize the uncus and its spatial relation to the cerebral peduncle. We describe the sliding uncus syndrome.

Unilateral pupillary mydriasis from nebulized ipratropium bromide: A false sign of brain herniation in the intensive care unit

Although there are many causes of anisocoria in the intensive care setting, the development of unilateral mydriasis in patients with intracranial hemorrhage or tumor is a neurological emergency, as it may herald the onset of uncal herniation. We describe two patients with a hemiparesis from neurosurgical disorder who subsequently developed a fixed and dilated pupil. The pupillary abnormality was caused by nebulized ipratropium bromide in both cases, and resolved when the medication was discontinued. Nebulized ipratropium may leak from the mask into ipsilateral eye and cause mydriasis in patients with facial weakness. This benign cause of anisocoria in the intensive care setting is distinguished from uncal herniation by the laterality of neurologic findings, and lack of mental status change, ptosis, and extraocular movement impairment.