Full-Endoscopic Surgery for Hypothalamic Hamartoma Resection

Summary

Hypothalamic hamartomas are rare, non-neoplastic congenital malformations mainly arising from the inferior hypothalamus or tuber cinereum. Surgical treatment is one of the most effective options, and the surgical approach must be precisely determined for each patient. Here, we describe the full-endoscopic technique for resecting hypothalamic hamartomas.

Abstract

Hypothalamic hamartomas (HH) are rare developmental anomalies of the inferior hypothalamus that often cause refractory epilepsy, including gelastic seizures. Surgical resection is an effective method to treat drug-resistant epilepsy and endocrinopathy in a suitable patient group. Open surgery, endoscopic surgery, ablative procedures, and stereotactic radiosurgery can be utilized. In this study, we aimed to describe the full-endoscopic approach for HH resection. The technique involves the use of an intraoperative ultrasonography (USG) system, a 30° rigid endoscope system that has an outside diameter of 2.7 mm with two working channels, a stylet that has an outer diameter of 3.8 mm, a monopolar coagulation electrode, a fiberoptic light guide, and the endovision system. Microforceps and monopolar electrocautery are the two main surgical instruments for HH removal. The protocol is easy to apply after a particular learning curve has been passed and shorter than open surgical approaches. It leads to less blood loss. Full-endoscopic surgery for HH is a minimally invasive technique that can be applied safely and effectively with good seizure and endocrinological outcomes. It provides low surgical site pain and early mobilization.

Introduction

Hypothalamic hamartomas (HHs) are non-neoplastic, heterotrophic tissues that contain neuronal and glial tissue in an abnormal distribution. Incidence rates of HHs are 1 in 50,000-1,000,000 people with male predominance¹. HHs present different clinical symptoms, such as precocious puberty, cognitive impairment, behavioral changes, and various types of seizures, most characteristically, gelastic seizures. Mostly gelastic seizures, as well as other seizure types, are extremely refractory to antiepileptic drugs (AEDs)^2,3.

Based on their morphology and relation to the hypothalamus, there are several classifications for HHs. The symptoms and the severity depend mainly on the size, location, attachment type, and degree of hypothalamic displacement. Seizures and behavioral, cognitive, and hormonal problems mostly originate from sessile HHs. Pedunculated HHs mainly cause precocious puberty^4,5,6.

Seizures can be controlled surgically either by resection or disconnection of the lesion. Most favorable outcomes were obtained from near-total or total resections⁴. The main goal is to prevent the spreading of the epileptic burst and thus stop secondary generalized seizures. Open surgery, either pterional, transcallosal, or transventricular approach, leads to good surgical outcomes; however, the complication rate is high, up to 30%. Laser and radiofrequency thermocoagulation-based disconnection surgeries, stereotactic radiosurgery, and focused ultrasound are also described as alternatives to open surgery. The treatment approach should be selected individually since the hypothalamic area, and close structures are critical^5,6,7.

The possibility that an endoscopic approach could achieve HH resection was first described in 2003⁸. Other authors have also shown the feasibility of endoscopic resection and disconnection surgeries for HH. These studies led us to believe that, especially in sessile intrahypothalamic HHs, a full-endoscopic approach is feasible^7,9,10,11. Surgical indications are mainly medically intractable gelastic seizures, neurobehavioral deterioration, and intractable endocrinopathy. Potential risk factors for surgery are mainly memory loss, endocrinopathy, behavioral and cognitive problems, and vision loss. With recent technological advancements in neuroendoscopy and surgical instruments, this study aimed to describe our technique of full-endoscopic approach for HH resection^3,12,13.

CASE PRESENTATION:
A 15-year-old boy was born at term by normal vaginal delivery. The patient had first seizures 7 years ago. Perinatal history was unremarkable. First seizures were characterized by gelastic seizures; however, after 2 years, the seizures changed character, becoming tonic type. The seizure frequency was 9-10 times per day. Neurological examination revealed moderate mental retardation and no neurological deficit. From the beginning of the seizures, the patient was administered carbamazepine, valproic acid, phenobarbital, lamotrigine, levetiracetam, and clobazam in different combinations. But there was no improvement in his condition. Magnetic resonance imaging (MRI) revealed a hamartoma of the right hypothalamus. A routine scalp electroencephalography (EEG) showed active epileptogenic focus in the right frontocentral and temporal regions. During video-EEG, 10 seizures were recorded. The electrographic discharge showed a right-sided origin. Ictal and interictal single-photon emission computed tomography (SPECT) and positron emission tomography (PET) were noncontributory. Neuropsychological tests (NPT) were not performed, as the patient was not cooperative. The patient did not have endocrinological issues such as precocious puberty, and all hormonal parameters were within normal range. Since the patient had medically intractable seizures and moderate mental retardation, surgical resection of the HH was decided.

The patient did not have any complications after surgery, nor did he experience diabetes insipidus (DI) or any other endocrinopathies. The ophthalmological exam was normal, and there was no central hyperphagia or fever. The patient was discharged on postoperative Day 5. In the 25^th month after surgery, he was followed up seizure-free, Engel class 1. A control MRI 2 years postoperatively showed no recurrence of the HH. The patient and his relatives stated that the patient had a better educational level and cognition; however, testing regarding neurocognition was not applied.

Protocol

The study protocol was approved by the institutional review board of Istanbul University Faculty of Medicine. Informed consent was obtained from patients for this study. 1. Preoperative procedures NOTE: Preoperative evaluation is similar to any other medically intractable epilepsy patient. Routine scalp electroencephalography (EEG) monitoring and video-EEG monitoring, interictal and ictal single photon emission computed tomography (SPECT), magnetic re…

Representative Results

An example of a patient treated by a full-endoscopic approach for HH resection has been presented. The preoperative MRI, intraoperative endoscopic view, and postoperative MRI have been shown in Figure 1, Figure 2, and Figure 3. There was minimal blood loss during the procedure, so it could not be measured. The procedure is short for a surgeon experienced in neuroendoscopy. For the represented case, the operation dur…

Discussion

In 2003, Delalande classified HHs into four subtypes. Type 1 HHs are small peduncular lesions attached to the tuber cinereum, type 2 HHs are lesions protruding to the third ventricle, type 3 lesions are the combination of type 1 and type 2 HHs, and type 4 HHs are large lesions with a broad attachment to both mammillary bodies and hypothalamus and have an extension to the interpeduncular cistern⁸. Depending on the location of the HH, various open surgery approaches have been described. For HHs near…

Materials

Burr-hole probe of intraoperative ultrasound system	Hitachi	UST-52114P	Aloka Linear UST-52114P, Frequency Range: 8 – 3 MH, Scan Angle: 90° FOV
Fiberoptic light guide	RiwoSpine	806635231	80663523 fiber light cable Ø 3.5 mm, TL 2.3 m, 8095.09 adaptor endoscope side, 8095.07 adaptor projector side
Intraoperative Ultrasound system	Hitachi		Hitachi Arietta 70, Tokyo, Japan
Microforceps	RiwoSpine	89240.3023
Monopolar-coagulating electrode	RiwoSpine	8922095000
Rigid neuroendoscope	Karl Storz	8921092051	30° Hopkins pediatric telescope, outside diameter 2.7 mm
Sheath for the telescope	Karl Storz	892209510	3.8 mm outside diameter with two working channels