A Unique Pediatric Case of Intratumoral Hemorrhage in a Sporadic Vestibular Schwannoma.

Vestibular schwannomas (VSs) are tumors that commonly occur in the eighth cranial nerve. They are usually associated with type 2 neurofibromatosis. They are uncommon in children, and sporadic cases of pediatric VS are even rarer. In general, VSs are benign lesions with less than 1% chance of intratumoral hemorrhage. Adult cases of hemorrhage in VS are well documented. We present the first pediatric case of intratumoral hemorrhage in VS in the absence of any features of NF in an 11-year-old child who complained of holocranial headache and sensorineural hearing loss in the left ear. We further discuss the pathogenesis and clinical features, and review the literature of intratumoral hemorrhage in patients of VS. Copyright:

Introduction

Vestibular schwannomas (VSs) are benign, encapsulated tumors arising from the peripheral nerve sheath of superior division of vestibulocochlear nerve. They are generally seen in adults and are rare in children (0.9%–2.08% of all unilateral acoustic neurinomas). Although a majority of VS in adults are sporadic, only 5% cases are associated with neurofibromatosis type 2 (NF2). However, most cases in the pediatric age group are associated with NF2 and sporadic cases are rare.[1] Patients with VS usually present with sensorineural hearing loss (98%), tinnitus (70%), disequilibrium or vertigo (67%), and headache (32%). Hemorrhage is uncommon in VS: only less than 50 cases have been reported in the literature with almost all belonging to the adult age group.[2345] In addition, only four cases of repeated intratumoral hemorrhage (ITH) have been reported and their occurrence has also been found exclusively in adolescents and adults.[6] Such patients present with a sudden onset of headache, nausea, vomiting, and vertigo. Less common symptoms include altered sensorium, diplopia, ataxia, gait disturbance, and facial hypesthesia[78] that are associated with a poor prognosis. However, no pediatric case of ITH in VS has ever been reported in the past. We hence present the first pediatric case of ITH in VS that had a good postsurgical outcome.

Case Report

An 11-year-old boy presented to the emergency room complaining of holocranial headache and vomiting since the evening before. Few hours before the onset of his symptoms, he was playing in the playground and suffered a minor trauma. He was treated by the family physician with medications that provided symptomatic relief. However, he experienced a recurrence of the headache the next morning along with difficulty in walking because of loss of balance with a tendency to fall on his left side, for which he was referred to our institute. On examination, he was found conscious, oriented, and had normal vital parameters. Cranial nerve examination revealed no abnormalities except sensorineural deafness in the left ear. Cerebellar signs such as heel–knee test, finger nose test, and dysdiadochokinesia were positive on the left side. Power, tone, and sensations were normal in both upper and lower limbs. Babinski sign was positive on both sides. Funduscopy examination revealed bilateral mild papilledema. Audiometric testing confirmed left-sided moderate grade sensorineural deafness. Computed tomography (CT) scan of the brain showed a well-defined lesion in the left cerebellopontine angle with central hypodensity and peripheral enhancement [Figure 1A]. Magnetic resonance imaging (MRI) of the brain revealed a 3.5 × 4.2 × 3cm sized extra-axial mass lesion in the left cerebellopontine angle, which was well defined, heterogeneously enhancing on contrast. Lesion appeared homogenous hyperintense on Fluid-attenuated inversion recovery (FLAIR) sequences [Figure 1B] and heterogeneous hyperintense on T1-weighted images [Figure 1C] with central hypointensity. The lesion was extending laterally into the internal auditory meatus and compressing the fourth ventricle medially.

Figure 1

Post contrast CT scan of the brain showing heterogeneous enhancing mass lesion in left cerebellopontine (CP) angle (A). MRI brain images showing a 3.5 × 4.2 × 3cm size left CP angle mass lesion, which appeared homogenous hyperintense on Fluid-attenuated inversion recovery sequences (B) and heterogeneous hyperintense on T1-weighted images (C) with central hypointensity. Postoperative CT scan showing complete excision of lesion (D). Postoperative MRI showing complete excision of lesion on T1-weighted images (E) and on post contrast study (F)

He underwent left retro mastoid suboccipital craniectomy in the lateral position. The dura was opened vertically near the lateral margin of the craniectomy. Cerebellum was found to be full and tense. By gently retracting the cerebellum upward and medially, the left cerebellomedullary cistern was opened and the cerebrospinal fluid was drained slowly till complete relaxation of the cerebellum was achieved. On gently retracting the cerebellum medially, a grayish red tumor capsule was visualized. On opening the tumor capsule, a gush of hemorrhagic fluid under pressure was drained out. The solid component of the tumor was excised with microsurgical techniques. The internal auditory meatus was drilled and the part of the tumor extending into the meatus was also excised after identifying and preserving the facial nerve at its anterosuperior location. Complete excision of the tumor was ensured and hemostasis was confirmed. The dura was closed watertight and the closure was carried out in layers.

Postoperatively, his headache and vomiting subsided immediately and his walking improved. He had House–Brackmann grade 3 facial weakness, which improved to grade 5 at the end of 4 weeks. Histopathological examination of the specimen showed Antoni A and B cells with areas of hemorrhage within the tumor [Figure 2]. Immediate postoperative CT scan showed complete excision of lesion [Figure 1D]. Postoperative MRI showed complete excision of lesion on T1 weighted images [Figure 1E] and on post contrast study [Figure 1F]. At 1-year follow-up, the patient was completely asymptomatic with normal left facial nerve function.

Figure 2

Photomicrograph showing Antoni A and Antoni B cells with evidence of ITH

Discussion

VSs are benign tumors that commonly affect the eighth cranial nerve and hence are most commonly found in the cerebellopontine angle.[5] They have a strong association with NF2, which is an autosomal-dominant disorder. These tumors are more common in adults and are specifically most prevalent in the fifth and sixth decade of life. Their prevalence in children less than 9 years of age is less and is estimated to account for 0.9% of all acoustic schwannomas. Very rarely however, VS may occur sporadically in a child without any features of NF2.[14] Acoustic schwannomas associated with NF-2 account for 2%–4% of all acoustic schwannomas with the mean patient age being younger than that of sporadic schwannomas.[2] Sporadic VS usually presents with sensorineural hearing loss (98%), tinnitus (70%), disequilibrium or vertigo (67%), and headache (32%).[789] Unlike in adults, the early symptoms of VS are easily neglected in children. Hence in children, the tumors are often identified by the more overt signs caused by the space occupying nature of the tumor, which include headache, vomiting, and loss of balance. This delay in diagnosis of months to years is the reason for the large size of such tumors in children.[1]

In intracranial tumors, hemorrhage is reported to be approximately 1.4%–10% and is more common in malignant and highly vascular lesions such as high-grade glioma, metastatic tumor, melanoma, and pituitary tumors.[31011] In slow-growing benign tumors such as meningioma, VS, and low-grade glioma, such hemorrhage is rare. In VS, hemorrhage is reported in <1% of the patients. Since the initial report of ITH in VS by McCoyd et al.[12] in 1974, more than 50 cases of hemorrhagic VS have been reported in the literature in the form of case reports and case series.[2] Our sporadic case of an 11-year-old boy is one of its kind as this is the only pediatric case reported with ITH in an acoustic schwannoma. ITH causes a sudden increase in the size of the tumor. The most common presenting symptoms are sudden-onset headache, nausea, vomiting, and vertigo.[3] The less common symptoms may include altered sensorium, diplopia, ataxia, gait disturbance, and facial hypesthesia.[78]

Although several mechanisms have been proposed, the exact etiology of ITH in VS is unknown. It has been widely postulated that tumor-induced angiogenesis produces arterial walls lacking media, which predisposes this vasculature to rupture. Occlusion of intratumoral vessels and necrosis of distal vessels are other mechanisms of ITH. High mindbomb homolog (MIB) index reflects rapid tumor growth due to high tumor doubling rate. Occasionally ITH associated with high MIB index and rapid growth of tumor is blamed for ITH.[13] ITH is not always associated with rapid growth rate.[14]

In adults, several predisposing factors for tumoral bleeding have been noted in acoustic schwannoma such as the mean tumor diameter (a mean diameter of 3.7cm is associated with hemorrhage),[8] cystic VS,[15] anticoagulation,[8] previous history of stereotactic radiation,[16] minor trauma,[17] strenuous exercise, or even severe effort.[14] Increased vascularity, thinning of tumor-associated vasculature, and mixed Antoni A and B cellularity are histopathologic characteristics of hemorrhagic VS that have been suggested to correlate with hemorrhage.[31819]

Treatment options for cases of VS include observation, radiation therapy, and surgical resection. The treatment approach of a VS presenting with ITH has not been clearly defined. Because of the limited number of reported cases available in literature at present, each case needs to be approached individually. Surgical excision is the best option available.[2021] Prognosis of these patients after surgical excision is good. However, ITH in adult VS is associated with significant morbidity and mortality. The reported incidence of facial nerve palsy and mortality is much higher in all cases of VS compared to that of patients with hemorrhagic VS.[17] As sporadic VSs in pediatric population are rare, decision for the best treatment options is complicated.[22] They can be best treated by microsurgical resection with good clinical outcome. Equally good long-term results can be achieved by radiation therapy. However, ITH in sporadic case of pediatric VS should be best treated with microsurgical excision.

Conclusion

Although unilateral VSs in children are rare, they do occur in the absence of features of NF. ITH in VS has been reported multiple times in the adult population, but no such pediatric documentation exists. However, in view of our case, such a possibility exists. Pathologic microvasculature within VS predisposes ITH following minor trauma. ITH in VS potentially increases the risk of neurologic deficit, especially hearing loss and facial dysfunction, hence demanding special attention to ensure good surgical outcome. Such a good clinical outcome including facial preservation can be achieved with microsurgical excision.

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Conflicts of interest

There are no conflicts of interest.