Giant Hypothalamic Hamartoma
A giant hypothalamic hamartoma (GHH) is a rare congenital malformation only reported in a few cases in the literature and is often associated with precocious puberty, gelastic seizures, or less commonly, Pallister-Hall syndrome. Persistent syndrome of inappropriate antidiuretic hormone secretion (SIADH) is very rare in infancy, and most patients with GHH do not develop persistent SIADH, usually only transient electrolyte disturbances postoperatively. Previous cases of GHH have not been associated with persistent derangements in antidiuretic hormone levels 1).
Treatment
Giant HH is an exceptionally difficult neurological disease. Primary hypofractionated GKRS may be an alternative approach as mono/multitherapy with promising results and minimal complication 2).
Although the exploration of epileptic activity and the extent of ablation are limited by the number of SEEG electrodes for the complete disconnection. One-stage high-density focal stereo-array SEEG-guided radiofrequency was safe and effective for treating pediatric giant HH patients. It can be an alternative method to treat giant HHs where LITT is unavailable 3).
Stereotactic radiofrequency thermocoagulation (SRT) provided minimal invasiveness and excellent seizure outcomes even in patients with giant HHs 4).
Cases
A 7-month-old male infant presented to our hospital with a history of an intracranial cystic lesion diagnosed at 23 weeks gestational age (GA), later impressed as a solid-cystic mass at 37 weeks GA by ultrasound prenatally. Postnatal MRI after birth showed a large mass with a dorsal cyst occupying the hypothalamus, causing hydrocephalus and brainstem compression. The patient started to have subtle seizures on the seventh day after birth and eventually developed dacrystic seizures. Hyponatremia with persistent SIADH was observed at 3 months of age before surgery. He received long-term oral sodium supplementation, polytherapy of anti-epileptic medications, ventriculocystostomy for progressive enlargement of the cystic cavity, and later surgical treatment for disconnection and partial resection which confirmed a histological diagnosis of hypothalamic hamartoma.
Conclusion: In this case study, we present a novel association of GHH with persistent SIADH and a rare presentation of a cystic component at the dorsal part of the tumor. Clinicians should be aware of this potential endocrine derangement and provide emergent treatment 5).
Three pediatric patients (age range 17-65 mo) underwent primary hypofractionated GKRS in 2-3 consecutive days with an interfraction interval of 24 h. All patients had precocious puberty and were on GnRH analog. Frame-based GKRS was done with 8.1-9.2 Gy radiation per fraction at 50% isodose in 2-3 fractions targeting the entire hamartoma volume. The mean target volume was 5.67 cc (4.45-7.39 cc). The authors followed these patients for clinical and endocrinological assessment at every 6 mo interval while the repeat MRI has done at 6 mo and then annually. The seizure outcome analysis was done using the Engel Epilepsy Surgery Outcome Scale.
At a mean follow up of 27 mo (24-30 mo), 2 patients became Engel class 3 while one achieved Engel class 1 control. 2 patients showed halted pubertal growth with no additional hormonal aberration. 2 patients showed significant volumetric reduction (48% and 32%) and patchy necrosis inside the hypothalamic hamartoma (HH). There was no deficit in visual function, memory and cognition. One patient showed reduction in aggressiveness.
Giant HH is an exceptionally difficult neurological disease. Primary hypofractionated GKRS may be an alternative approach as mono/multitherapy with promising results and minimal complication 6)
Wang et al. analyzed the clinical data of six patients with giant HHs (masses with a maximum diameter >30 mm) who underwent stereotactic electrode implantation between November 2017 and April 2019. After a multidisciplinary discussion, we designed a high-density focal stereo-array electrode implantation strategy. SEEG-guided bipolar coagulations were performed between two contiguous contacts of the same electrode, or between two adjacent contacts of different electrodes. Results: Among the six patients, three were male and three were female, with an average age of 5.08 ± 4.73 years (range, 1.4-12 years); the average follow-up duration was 20.17 ± 5.49 months. One patient had previously undergone open surgery. Four patients had gelastic seizures, one had gelastic and tonic seizures, and one had gelastic and generalized tonic-clonic seizures. The number of implanted electrodes ranged from 3 to 7, with an average of 5.33. One patient had transient diabetes insipidus after the operation, and no child had fever or new hormone metabolisms disorder after surgery. Four patients had Engel I classification outcomes (free from disabling seizures), and two patients had Engel II classification outcomes. Conclusion: Although the exploration of epileptic activity and the extent of ablation are limited by the number of SEEG electrodes for the complete disconnection. One-stage high-density focal stereo-array SEEG-guided radiofrequency was safe and effective for treating pediatric giant HH patients. It can be an alternative method to treat giant HHs where LITT is unavailable 7).
Cristobal et al. presented a unique case of an asymptomatic giant hypothalamic hamartoma diagnosed prenatally by fetal magnetic resonance imaging and followed throughout infancy. This case demonstrates the utility of multimetric analysis using difference sequences, including diffuse-weighted imaging, to assess specific properties of intracranial lesions detected in utero and to aid in accurate diagnosis prior to birth 8).
A 10-month-old girl child presenting with drug-resistant seizures and a giant hypothalamic lesion that was confirmed as hamartoma on histopathology. Surgical decompression and disconnection from the hypothalamus was performed with the intent of controlling her seizures. Unfortunately, the patient developed right middle cerebral artery and posterior cerebral artery territory infarction, possibly due to vasospasm or thrombosis of the vessels. The patient had a stormy postoperative course but has recovered well neurologically at the 18-month follow-up. Histopathological examination revealed abnormal clusters of NeuN-positive neurons, which was confirmatory of hypothalamic hamartoma 9).