Paula L. Pyzik

Hemispherectomy for intractable unihemispheric epilepsy etiology vs outcome.

Background: Surgical removal of one hemisphere has been performed for several decades to treat intractable unihemispheric epilepsy. A prior case series focused on the outcomes after 58 surgeries at Johns Hopkins Hospital in 1997. This series, and an additional 53 cases, were reviewed to bring the outcomes up to date. Methods: Charts of the 111 patients undergoing hemidecortications at the Pediatric Epilepsy Center from 1975 to 2001 were reviewed and families were contacted. Three children died in the immediate perioperative period and three were lost to follow-up immediately after surgery. Follow-up ranged from 3 months to 22 years. Results: Two children died several years later due to intractable seizures. Overall, 65% are seizure-free, 21% have occasional, non-handicapping seizures, and 14% have troublesome seizures. Eighty percent are on one anticonvulsant or none and 89% are able to walk without assistance. Etiology strongly predicted seizure outcome. Patients with migrational disorders are less likely to be seizure-free than all other etiologies (predominantly Rasmussen and congenital vascular injuries) combined (51% vs 71%, p = 0.05). Conclusions: Hemidecortication continues to be a beneficial procedure in reducing seizure frequency in cases of unilateral cortical epilepsy. Fewer children with migrational disorders are seizure-free.

Growth of children on the ketogenic diet

This is a prospective cohort study of 237 children (130 males, 107 females) placed on the ketogenic diet for control of intractable epilepsy (mean age at starting diet 3 years 8 months; age range 2 months to 9 years 10 months); average length of follow-up was 308 days. There were 133 children on the diet at 1 year and 76 at 2 years. Height and weight measurements were converted into age- and sex-appropriate z scores. There was a rapid drop in weight z scores in the first 3 months. After this initial period, the weight z score remained constant in children who started the diet below the median weight for their age and sex, although z scores continued to decrease in children starting above the median. There was a small decrease in height z scores in the first 6 months (<0.5); however, there were larger changes by 2 years. There was no difference based on sex for either height or weight. The ketogenic diet generally provides sufficient nutrition to maintain growth within normal parameters over a defined period. Very young children grow poorly on the diet and should be followed-up carefully over long periods of use.

Kidney Stones, Carbonic Anhydrase Inhibitors, and the Ketogenic Diet

Summary:  Purpose: Because carbonic anhydrase inhibitors and the ketogenic diet are each known risk factors for kidney stones, simultaneous use of these therapies has been discouraged. The objective of this study was to establish the prevalence of nephrolithiasis in children in this combination‐therapy population.

The Ketogenic Diet : Adolescents Can Do It, Too

Summary:  Purpose: To determine both the efficacy of and compliance with the ketogenic diet in the adolescent population.

A blinded, crossover study of the efficacy of the ketogenic diet.

Despite over 80 years of use, the ketogenic diet (KD) has never been tested in a blinded manner. Twenty children with intractable Lennox‐Gastaut syndrome (LGS) were fasted 36 h and then randomized to receive the classic KD in conjunction with a solution containing either 60 g/day of glucose or saccharin. Parents and physicians were blinded to both the solution composition and level of ketosis. A crossover to the KD with the alternate solution occurred following the sixth day and a repeat fast. A 24‐h electroencephalography (EEG) was obtained at baseline and after each arm. After administration of the solution, there was moderate evidence of a reduction in parent‐reported seizures between the glucose and saccharin arms, with a median difference of 1.5 seizures per day (p = 0.07). There was no reduction in the number of EEG‐identified events, with a median reduction of 7 events per day (p = 0.33). Ketosis was not completely eliminated in the glucose‐added arm.

A randomized, crossover comparison of daily carbohydrate limits using the modified Atkins diet.

The modified Atkins diet is a dietary therapy for intractable epilepsy that mimics the ketogenic diet, yet does not restrict protein, calories, and fluids. The ideal starting carbohydrate limit is unknown. Twenty children with intractable epilepsy were randomized to either 10 or 20 g of carbohydrates per day for the initial 3 months of the modified Atkins diet, and then crossed over to the opposite amount. A significantly higher likelihood of >50% seizure reduction was noted for children started on 10 g of carbohydrate per day at 3 months: 60% versus 10% (P=0.03). Most parents reported no change in seizure frequency or ketosis between groups, but improved tolerability with 20 g per day. A starting carbohydrate limit of 10 g per day for children starting the modified Atkins diet may be ideal, with a planned increase to a more tolerable 20 g per day after 3 months.

Kidney Stones and the Ketogenic Diet: Risk Factors and Prevention:

A cohort study was performed of children started on the ketogenic diet for intractable epilepsy from 2000 to 2005 (n = 195). Children who developed kidney stones were compared with those without in terms of demographics, urine laboratory markers, and intervention with urine alkalinization (potassium citrate). Thirteen children (6.7%) developed kidney stones. The use of oral potassium citrate significantly decreased the prevalence of stones (3.2% vs 10.0%, P = .049) and increased the mean time on the ketogenic diet before a stone was first noted (260 vs 149 patient-months, P = .29). The prevalence of kidney stones did not correlate with younger age or use of carbonic anhydrate inhibitors (eg, topiramate or zonisamide) but trended toward higher correlation with the presence of hypercalciuria (92% vs 71%, P = .08). No child stopped the diet due to stones; in fact, the total diet duration was longer (median 26 vs 12 months, P < .001). Kidney stones continue to occur in approximately 1 in 20 children on the ketogenic diet, and no statistically significant risk factors were identified in this cohort. As oral potassium citrate was preventative, prospective studies using this medication empirically are warranted.

Polysomnography after adenotonsillectomy in mild pediatric obstructive sleep apnea

OBJECTIVES a) To determine the need for intensive monitoring on the first operative night of surgery in children undergoing adenotonsillectomy for mild obstructive sleep apnea; b) to examine the effect of narcotics on postoperative obstructive sleep apnea. DESIGN Randomized, prospective study. SETTING University hospital. PATIENTS Children, ranging in age between 1 and 18 yrs, presented to the Pediatric Otolaryngology Clinic for adenotonsillectomy for mild obstructive sleep apnea defined as from one to 15 obstructive apnea events per hour on preoperative polysomnogram. INTERVENTIONS Patients were assigned to receive either a narcotic- or a halothane-based anesthetic for adenotonsillectomy. A postoperative polysomnogram was performed in the pediatric intensive care unit on the first operative night. MEASUREMENTS AND MAIN RESULTS Eighteen patients were recruited, 15 of whom met inclusion criteria: nine patients received a halothane-based anesthetic and six patients received a fentanyl-based anesthetic. When the data were analyzed by pooling both groups, the differences between pre- and postoperative sleep studies demonstrated a reduction in the number of obstructive events and less severe oxygen desaturations on the operative night. Total sleep time between the two sleep studies decreased from 371 +/- 13 to 304 +/- 14 mins. The number of obstructive apnea events/hr decreased as well. The lowest oxygen saturation measured during rapid eye movement sleep was 78 +/- 5% preoperatively and 92 +/- 1% postoperatively. CONCLUSIONS Our data suggest that children without underlying medical conditions, neuromotor diseases, or carniofacial abnormalities, 1 to 18 yrs of age, who suffer from mild obstructive sleep apnea, have improvements documented by polysomnography on the night of surgery following adenotonsillectomy and do not necessarily need to be monitored intensively. These findings were not significantly affected by the choice of intraoperative anesthetic.

Long-term outcomes of children treated with the ketogenic diet in the past.

Purpose:  The ketogenic diet has well‐established short‐ and long‐term outcomes for children with intractable epilepsy, but only for those actively receiving it. However, no information exists about its long‐term effects years after it has been discontinued.

Polysomnographic characteristics of patients with Rett syndrome

During wakefulness, patients with Rett syndrome have disordered breathing. To understand further this ventilatory control disorder, we performed polysomnography in 30 patients with Rett syndrome and 30 control subjects (female subjects with primary snoring). The median age was 7 years (range, 1 to 32 years) for Rett syndrome and 6 years (range, 1 to 17 years) for control subjects. During periods of wakefulness, 67% of patients with Rett syndrome had the characteristic pattern of disordered breathing (i.e., episodes of hyperventilation followed by central apnea and desaturation). No such events occurred during sleep. Sleep efficiency and sleep architecture were similar for both groups. During sleep, there was no difference in duration of periodic breathing, number of episodes of central apnea with desaturation, or number of episodes of obstructive apnea or end-tidal carbon dioxide tension between the two groups. Although arterial oxygen saturation during rapid eye movement (REM) sleep was slightly lower in patients with Rett syndrome (nadir, 94% +/- 2% vs 96% +/- 2%), it remained within the normal range. Parental history reflected the awake respiratory findings in most cases. We conclude that patients with Rett syndrome have normal breathing during non-rapid eye movement (NREM) sleep. We speculate that patients with Rett syndrome have normal brain-stem control of ventilation, and that the disordered breathing seen during wakefulness is due to an abnormality of the cortical influence on ventilation.