Early surgical intervention for structural infantile spasms in two patients under 6 months old: a case report

Infantile spasms (IS) are the most common childhood epileptic encephalopathy. Focal cortical dysplasia (FCD) and gray matter heterotopias (GH) are common structural causes of IS. The recommended first-line treatment for IS patients with structural causes is surgical intervention, according to the International League Against Epilepsy (ILAE) commission guidelines. However, there is currently no consensus on appropriate timings of surgery. Two structural IS cases are presented here: one was caused by FCD, and the other by GH. Both patients exhibited recurrent seizures at the age of 2 months, had poor responses to various antiepileptic drugs (AEDs) and displayed severe mental and motor developmental retardation. Seizure types included focal seizures and spasms. Brain magnetic resonance imaging showed abnormal gray signal or suspicious FCD lesions that coincided with the origin of the focal seizures. The patients underwent lesion resection before the age of 6 months. Follow-up observation showed that seizures of both patients were completely controlled several days after the surgery. All AEDs were gradually reduced in dosage within 1 year, and the mental and motor development almost returned to normal. Early resection of lesions in structural IS patients has benefits of effectively controlling convulsions and improving developmental retardation. Infants at several months of age can well tolerate craniotomy, and their cognitive development is more likely to return to normal after early surgery.


Background
West syndrome (WS), also known as infantile spasms (IS), occurs in infancy with a peak between 4 and 7 months of age. WS has three characteristics: spasms, neurodevelopmental regression, and hypsarrhythmia on electroencephalogram (EEG) [1]. The International League Against Epilepsy (ILAE) commission classifies the etiologies of WS into genetic, structural, metabolic and unknown causes [2]. According to the ILAE guidelines, the recommended first-line treatment for IS patients with structural causes is surgical intervention [3]. In recent years, multicenter studies have shown that surgical treatment can terminate or significantly alleviate seizures in some IS patients with localized brain abnormalities [4]. However, precisely how surgical variables (i.e., timing of surgery and duration of epilepsy prior to surgery) influence neurodevelopmental outcomes remains to be determined.

Case presentations
Here, we present two IS cases. Both patients exhibited recurrent seizures including focal seizures and typical spasms, had no response to medical interventions, and displayed moderate to severe developmental retardation.

Case 1
This female patient exhibited recurrent seizures when she was a 50-day-old baby. Video EEG before surgery showed background hypsarrhythmia and within 15 h, 7 seizure attacks, including 3 spasms (Fig. 1b) and 4 focal seizures starting on the left occipital region (Fig. 1c). Cerebral MRI showed a gray signal in a semiovale located in the left parietal-occipital lobe, which was considered to be the congenital heterotopic gray matter (Fig. 1a). The patient received treatment with phenobarbital, levetiracetam, vigabatrin, adrenocorticotropic hormone (ACTH), nitrazepam and lamotrigine before surgery, but none of these antiepileptic drugs (AEDs) showed promising efficacy. At the age of 5 months, the baby patient underwent neurosurgical resection. According to the stereotactic positioning, a 2.5 cm × 2.0 cm × 2.5 cm lesion was resected (Fig. 2a). Pathological examination results were consistent with the characteristics of gray matter heterotopias (GH) (Fig. 2b-d).

Case 2
The patient was a female infant who experienced recurrent seizures at 2 months and 25 days. Video EEG before surgery showed many sharp waves, spikes and spikeslow waves in the right central and midline areas during the interictal period; within 4 h, 3 partial-spasm seizures occurred originating from the right hemisphere (Fig. 3b, c). Cerebral MRI revealed an abnormal lesion in the right frontal cortex, which was considered as focal cortical dysplasia (FCD) (Fig. 3a). She was treated consecutively with levetiracetam and topiramate, but showed poor effects. Considering the parents' concerns on the side effects of hormones, and the previously-reported negative response of structural IS to ACTH, ACTH was skipped and preoperative assessments were conducted when the patient was 4 months old. Intracranial EEG recording ( Fig. 4a-d) during a seizure attack showed that the origin site of epileptic discharge coincided with the lesion on brain MRI (Fig. 3a). Then, she underwent neurosurgical intervention. According to the stereotactic positioning, a 3 cm×4 cm×3 cm lesion was resected. Combined with the MRI and pathological findings, the patient was diagnosed with FCD IIa (Fig. 3a, d).
Both the baby patients had good surgical tolerability, without disturbance of consciousness and limb movement disorder. The seizures were completely controlled several days after the surgery. All AEDs were gradually reduced within 6 months, and EEG recording showed normal activity (Fig. 1d for patient 1). During the 5-year follow up, both patients displayed almost normal mental and motor development.

Discussion
IS is a difficult-to-treat infantile epileptic encephalopathy by medications. Frequent seizures of IS, which can be up to hundreds of clinical and subclinical seizures per day, cause devastating effects on the brain development and cognitive levels of children, and more than 90% of patients have mental or motor developmental retardation. Some research pointed out that pediatric epilepsy surgery in infants and toddlers (< 3 years) offers significant opportunities for improving seizure frequency, neuro-cognitive development, and quality of life [5]. There are seven preadmission predictors for surgical candidacy: single semiology at seizure onset, structural etiology, one or more interictal foci in the same hemisphere, focal background electroencephalograph slowing, focal or hemispheric abnormality on magnetic resonance imaging, male sex, and normal development. In the presence of more than four factors, 91% were found to be surgical candidates [6]. Therefore, early surgery is recommended for those who are suitable for surgery in order to avoid intellectual and cognitive deterioration [7,8]. The surgical treatment of IS mainly includes two methods: resection and palliative surgery. The resection surgery is preferred for patients with definite etiology, focal seizures and an origin located in the non-functional areas [4]. The palliative surgery, which mainly cuts the corpus callosum, can be used for those who have no clear etiology or manifesting widely disseminated epileptiform discharges; neuromodulation techniques such as vagus nerve stimulation (VNS) and deep brain stimulation can also be considered [8,9]. Delphine et al. [10] reported three such patients who presented with IS between 5 and 7 months of age; two of the patients who underwent early hemispherotomy acquired normal verbal intelligence, whereas the third patient, who was the oldest and had the longest duration of epilepsy, was operated on at 38 months of age and remained with severe mental retardation. This indicated that early diagnosis and a shorter lag time to treatment are essential for the overall outcome of WS patients [1]. At present, the earliest age for surgical treatment for IS reported in the international literature is 2.5 months [11]. The earliest age for surgical treatment for IS in China is 10 months. A history of infantile spasms has been shown to be associated with a median of 3.0 years' shorter duration to surgery [12].
Kuwahara et al. [13] reported a 4-month-old female infant with atypical asymmetrical GH diagnosed with WS who underwent relatively low-dose ACTH therapy followed by a combination of valproic acid and clonazepam, and the seizures were well controlled. To date, the surgical treatment of GH-caused IS is rarely reported, and there is no consensus on how and when to treat GH combined with IS [14]. Here, we present a GH patient who manifested medically refractory epilepsy, including spasms and focal seizures, accompanied by severe developmental retardation. The patient underwent lesion resection at the age of 5 months, and showed seizure and behavioral improvement after the operation. As far as we know, this is the earliest report of neurosurgical intervention in GHinduced IS, and the patient is one of the few reported cases of lesionectomy with resultant improved behavior.
FCD is the most frequent histological finding in pediatric patients undergoing epilepsy surgery and is classified into different clinicopathological subtypes: type I, type II and type III [15]. FCD is a common structural cause of IS. Seizures from FCD are commonly refractory to medical treatment, and FCD accounts for up to 26% of pediatric epilepsy cases with surgical intervention [16]. Borggraefe et al. [17] have reported a patient who manifested FCD IIb-caused seizures within the first day of life, and received epilepsy surgery at the age of two and a half months with seizure-free outcome, suggesting that epilepsy surgery can be successfully performed in medically intractable patients with a clearly identifiable seizure onset zone within the first three months of life. This is the youngest age ever reported for surgical a Cerebral MRI revealed an abnormal signal in the right frontal cortex (arrow), manifested as a structural abnormality of the cortex and an unclear boundary between gray matter and white matter. b, c Video EEG during a focal seizure starting at the right central and midline area (b) and during spasm attacks (c). d HE staining revealed glial cell proliferation and atrophy of some neurons (× 200) treatment of FCD-caused neonatal drug-resistant epilepsy. In addition, the report also indicated that surgical management with a shorter latency period tended to have better developmental outcomes, as demonstrated in animal models [18], in which a short duration of seizures has less influence on the near normal brain. To date, studies exploring the cognitive effects of epilepsy surgery for FCD are limited. In 2010, Rouleet-Perez et al. [19] studied 11 children who underwent epilepsy surgery before age 6. Two of the children with FCD IIb showed a rapid improvement in developmental quotient testing following surgery. Over a long-term period, only one child with FCD type IIb showed continued developmental improvement; the remaining patients were stable in their testing and did not show significant catch-up long after surgery. In this study, patient 2 was diagnosed with FCD IIa combined with IS and had a poor response to AEDs. However, after receiving neurosurgical treatment at the age of 4 months, the patient showed good surgical tolerability, rapid control of convulsions, and gradual reduction of AEDs during follow up. In addition, her mental and motor development gradually returned to normal after rehabilitation.

Conclusion
Here the two patients are very young babies with structural IS who received lesion resection surgery at early age. Their seizures were completely controlled soon after surgery, AEDs were gradually reduced, and mental and motor development almost recovered to normal levels. This study demonstrates that early lesion resection has more benefits for seizure control and improvement of developmental retardation. We therefore recommend that IS patients pushed to surgical intervention as early as possible for those who have single semiology at seizure onset, structural etiology, one or more interictal foci all in the same hemisphere, focal background electroencephalograph slowing, focal or hemispheric abnormality on magnetic resonance imaging, and inability of regular AEDs to effectively control seizures. This strategy will help to improve intelligence and motor development. Our case report will provide hints for pediatricians and neurosurgeons in the treatment of structural IS.