Entrapment of the temporal horn (ETH) is a rare pathologic condition. It is a kind of focal hydrocephalus caused by obstruction of flow pathway of cerebrospinal fluid. It is caused by various conditions, but ETH secondary to postoperative gamma-knife radiosurgery (GKS) is extremely rare.

A 52-year old previously healthy woman underwent resection of a large intraventricular meningioma. A small fragment of residual tumor with no obvious enlargement of the temporal horn was observed 3 mo after surgery, and she was referred for GKS. Two months after GKS, she complained of headache and progressive paralysis of the left limb. Magnetic resonance imaging revealed enlargement of the temporal horn. There was a second procedure to resect the residual tumor 8 mo after GKS. After the second procedure, she recovered smoothly. As of the date of this writing, she has remained in good condition.

This case reminds us that ETH should be considered in the treatment of intraventricular meningiomas, especially before GKS.

Entrapment of the temporal horn (ETH) is characterized by dilation of the temporal horn of the lateral ventricle, caused by cerebrospinal fluid (CSF) obstruction at the trigone level. It is secondary to several pathological conditions, including infection[1], intraventricular hematoma[2], parasitic infection[3], arteriovenous malformation[4], and intraventricular tumors[5]. Most reported cases of ETH were secondary to these pathological conditions. However, gamma-knife radiosurgery (GKS) also can lead to ETH, although this situation has been rarely reported. Here we report the first case of ETH secondary to postoperative GKS.

She underwent intraventricular meningioma resection under general anesthesia via a transcortical approach. A small piece of tumor remained during the operation because of unstable vital signs. Postoperative pathological diagnosis confirmed meningioma. The patient recovered smoothly after surgery and symptoms disappeared gradually. A follow-up at 3 mo after surgery revealed residual tumor. She was in good condition at the time. She was then referred for GKS. Radiosurgery was performed with 32 Gy of five central points and a marginal dose of 16 Gy to 50% isodose curve, which lasted 2325 s. Two months after GKS, she developed a headache and progressive paralysis of the left limb. Follow-up magnetic resonance imaging revealed progressive expansion of the ventricular temporal horn. She then underwent a second operation 11 mo after the first procedure. At the second operation, the residual tumor was resected completely and the choroid plexus was coagulated (Figure 2).

Open in New Tab   Full Size Figure   Download Figure

Figure 2 Entrapment of the temporal horn secondary to postoperative gamma-knife radiosurgery in intraventricular meningioma. A: Pathology after first operation. Microscopically, the tumor cells were spindle-shaped and bundle-shaped with slightly larger and darker nuclei, and the diagnosis was meningioma; B: Pathology after second operation. Microscopically, the tumor cells were patchy, densely arranged, and slightly atypical, with massive necrosis and hemorrhage locally. The diagnosis was atypical meningioma.

After the second operation, she recovered rapidly with disappearance of headache and hemiparesis. She has remained well until the most recent follow-up 9 mo after the second surgery (Figure 3).

Open in New Tab   Full Size Figure   Download Figure

Figure 3 Timeline showing events starting from the onset of symptoms until ultimate outcome.

Recently, ETH after operation of the trigone meningioma has been brought into focus, which was seldom discovered before. As the development of imaging plays an important role in neurosurgery[6,7], dilation of the ventricle can be monitored by CT and MRI. In fact, dilation of the temporal horn of the lateral ventricle is not rare after surgery for intraventricular lesions[8], especially for trigone meningioma[9]. However, most are asymptomatic or can be treated with conservative therapy. Only few cases require surgical intervention because of progressive intracranial hypertension and mass effect caused by dilated temporal horn. Several factors were reported to be related to the occurrence of postoperative ETH, including meningitis after surgery, neurologic deficits after operation, and inappropriate ventricular drainage[5]. In our case, a large trigon meningioma was resected. None of the factors mentioned above were present in our case. Despite a small residual piece of tumor, no substantial dilation of the temporal horn occurred 3 mo after surgery. Nevertheless, two months after GKS, she suffered from headache and gradual symptom worsening. In our case, no high-risk factor related with ETH was observed; therefore, we speculated that ETH in our case was secondary to radiation damage induced by GKS. Radiation led to brain damage, including to the ventricular wall; this may have led to occlusion of CSF flow. Radiation-associated ETH was reported in only a girl with a diffuse parietoccipital AVM who underwent GKS[10]. GKS also can cause tumor edema and increase tumor volume, leading to ETH. To the best of our knowledge, ETH secondary to GKS in trigone meningioma has not been reported previously.

There are many methods to manage ETH, including V-P shunt[2], endoscopic temporal ventriculocisternostomy[11,12], frontal-to-temporal horn shunt[13], and temporal horn to prepontine cistern shunt[14]. In this case, resection of residual tumor was performed, and the patient recovered smoothly thereafter.

In conclusion, to the best of our knowledge, this is the first case of ETH after GKS in an intraventricular meningioma. This case reminds us that ETH should be considered when treating intraventricular meningiomas, especially before GKS.