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Information for Patients, Parents and Treating Doctors about Surgical Treatment of Hypothalamic Hamartomas in Children with Gelastic Epilepsy

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Dr. A. Simon Harvey Director, Children's Epilepsy Program

Assoc. Prof. Jeffrey Rosenfeld Director, Department of Neurosurgery

Elizabeth Grimmer Epilepsy Nurse Specialist, Children's Epilepsy Program

Royal Children's Hospital, Melbourne, Australia

Hypothalamic hamartomas (HH) may cause epileptic seizures, precocious puberty, learning difficulties and behaviour problems. Epileptic seizures are frequently of a gelastic (laughing) type but many children have additional tonic, tonic-clonic, absence and complex partial seizures. Seizures in children with HH are invariably resistant to medication and many children exhibit a gradual deterioration in seizure control and their general abilities over time.

Recent studies using ictal SPECT scans and intracranial EEG recordings have demonstrated that seizures in patients with HH arise from within the hamartoma. For this reason, a variety of surgical treatments directed at the HH have been employed recently in children and adults with refractory epilepsy . These include partial resection via a transsylvian or subtemporal approach, radiofrequency thermocoagulation via an open or stereotactic approach, stereotactic radiosurgery (gamma knife), and our complete resection or disconnection via a transcallosal-transventricular approach.

In contrast to HH causing isolated precocious puberty, which are often pedunculated lesions which are accessible to standard neurosurgical approaches from beneath the surface of the brain, HH causing gelastic epilepsy usually sit within the 3rd ventricle and involve the hypothalamus proper. Complete resection, ablation or disconnection of the HH is probably necessary to eliminate seizures and halt the neurological deterioration that often accompanies seizures. We believe that partial resection of HH via below, cortical resection and corpus callosotomy are ineffective treatments. Stereotactic ablative techniques, such as radiofrequency thermocoagulation and radiosurgery, hold promise but concerns exists about the accuracy of these techniques, the ability to completely destroy the HH, "collateral damage" to adjacent normal structures, and long-term side effects.

We have used a novel interhemispheric, transcallosal, interforniceal, transventricular approach to the HH in 6 children with gelastic epilepsy. This technique has been presented and favourably received at international epilepsy and neurosurgical meetings , and the results of surgery have been submitted for publication in an international neurosurgical journal now that we have significant experience and follow-up with the technique. The operative approach is similar to that used in 3rd ventricular surgery for other lesions, employing frameless MR stereotactic navigation and microsurgical operative techniques. The main advantage of this approach is that it allows direct visualisation of the HH within the 3rd ventricle and either complete resection or disconnection from hypothalamus proper (the walls and floor of the 3rd ventricle). Potential risks include injury to the fornices, mamillary bodies, hypothalamus proper, optic nerves and cranial nerves leading to memory, visual and endocrine problems. However, we believe that these risks are significantly lower than with standard approaches from below.

In the 5 operated children with follow-up from 3-31 months (average 18 months), seizures have been eliminated, medications have been reduced, behaviour and learning have improved, and no complications have occurred. Postoperative MRI scans in these 5 patients showed 96-100% resection of the HH.

Suitability for this surgical approach can be readily judged from review of the MRI scans, most importantly the coronal and sagittal projections. The preoperative workup entails a week in hospital for detailed neurological, neurosurgical, neuropsychological, endocrinological, ophthalmological, MRI, EEG and SPECT evaluations. The operation lasts approximately 3-5 hours, depending on the ease of access to the 3rd ventricle and the size and attachment of the HH. Postoperatively, children may have transient diabetes insipidus (water balance problems). Children stay in hospital for 6-10 days recovering from surgery. MRI, opthalmological, EEG and endocrine assessments are performed 10-14 days postoperatively, following which interstate or international patients can usually return home.

The Royal Children's Hospital is the largest, tertiary paediatric hospital in the southern hemisphere with specialist paediatric neurologists, neurosurgeons, anaesthetists and nurses.

Selected References

Arita K, Kurisu K, Iida K, Hanaya R, Akimitsu T, Hibino S, Pant B, Hamasaki M, Shinagawa S. Subsidence of seizure induced by stereotactic radiation in a patient with hypothalamic hamartoma. J Neurosurg 1998;89:645-8.

Cascino GD, Andermann F, Berkovic SF, Kuzniecky RI, Sharbrough FW, Keene DL, Bladin PF, Kelly PJ, Olivier A, Feindel W. Gelastic seizures and hypothalamic hamartomas: Evaluation of patients undergoing chronic intracranial EEG monitoring and outcome of surgical treatment. Neurology 1993;43:747-50.

Kuzniecky R, Guthrie B, Mountz J, Bebin M, Faught E, Gilliam F, Liu H-G. Intrinsic epileptogenesis of hypothalamic hamartomas in gelastic epilepsy. Ann Neurol 1997;42:60-7.

Nishio S, Morioka T, Fukui M, Goto Y. Surgical treatment of intractable seizures due to hypothalamic hamartoma. Epilepsia 1994;35:514-9.

Valdueza JM, Cristante L, Dammann O, Bentele K, et al.. Hypothalamic hamartomas: with special reference to gelastic epilepsy and surgery. Neurosurgery 1994;34:949-58.

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