The Incidence and Evolution of Parkinsonian Rigidity in Rett Syndrome: A Pilot Study.

BACKGROUND: Patients with Rett syndrome (RTT) may demonstrate parkinsonian features. Here, we report a preliminary cross-sectional and prospective evaluation of the evolution, regional distribution, and eventual incidence of rigid tone in a cohort of MECP2 mutation-positive patients. METHODS: In 51 participants, muscle tone rigidity in extremity regions and neck plus hypomimia were quantified using an RTT rigidity distribution (RTTRD) score with a range of 0 to 15. RTTRD scores were correlated with age, ability to walk and speak, mutation type, and, in a small subgroup (n=9), cerebrospinal fluid (CSF) homovanillic acid (HVA) and 5-hydroxyindole-acetic acid levels. RESULTS: Participant ages ranged from 2 years and 5 months, to 54 years. Rigidity was found in 43/51 (84.3%); it appeared as early as age 3, increased in extent with age, and was present in all participants aged ≥13. Ankle region rigidity appeared first, followed by proximal legs, arms, neck, and face. Ambulatory participants (n=21) had lower RTTRD scores than nonambulatory (n=30; p=0.003). We found a trend to lower scores in participants with retained speech (n=13) versus those with none (n=38; p=0.074), and no difference in scores for those with truncating (n=25) versus missense mutations (n=22; p=0.387). RTTRD scores correlated negatively with CSF HVA levels (R=-0.83; p=0.005), but not with 5-hydroxyindole-acetic acid levels (R=-0.45; p=0.22). CONCLUSIONS: Although assessment of muscle tone is somewhat subjective and the RTTRD has not been validated, this study nevertheless suggests that parkinsonian rigidity in RTT is common and frequently increases in extent with age; its severity correlates directly with impaired ambulation and inversely with CSF HVA levels.

S-adenosylmethionine and S-adenosylhomocysteine in plasma and cerebrospinal fluid in Rett syndrome and the effect of folinic acid supplementation.

Rett syndrome is a neurodevelopmental disorder characterized by cognitive and locomotor regression and stereotypic hand movements. The disorder is caused by mutations in the X chromosomal MECP2 a gene encoding methyl CpG-binding protein. It has been associated with disturbances of cerebral folate homeostasis, as well as with speculations on a compromised DNA-methylation. Folinic acid is the stable form of folate. Its derived intermediate 5-MTHF supports the conversion of homocysteine to methionine, the precursor of S-adenosylmethionine (SAM). This in turn donates its methyl group to various acceptors, including DNA, thereby being converted to S-adenosylhomocysteine (SAH). The SAM/SAH ratio reflects the methylation potential. The goal of our study was to influence DNA methylation processes and ameliorate the clinical symptoms in Rett syndrome. Therefore we examined the hypothesis that folinic acid supplementation, besides increasing cerebrospinal fluid (CSF) 5-MTHF (p = 0.003), influences SAM and SAH and their ratio. In our randomized, double-blind crossover study on folinic acid supplementation, ten female Rett patients received both folinic acid and placebo for 1 year each. It was shown that both SAM and SAH levels in the CSF remained unchanged following folinic acid administration (p = 0.202 and p = 0.097, respectively) in spite of a rise of plasma SAM and SAH (p = 0.007; p = 0.009). There was no significant change in the SAM/SAH ratio either in plasma or CSF. The apparent inability of Rett patients to upregulate SAM and SAH levels in the CSF may contribute to the biochemical anomalies of the Rett syndrome. Our studies warrant further attempts to promote DNA methylation in the true region of interest, i.e. the brain.

Determination of 5-methyltetrahydrofolate in cerebrospinal fluid of paediatric patients: reference values for a paediatric population.

BACKGROUND: Cerebral folate deficiency (CFD) has been described as a neurological syndrome associated with low 5-methyltetrahydrofolate (5-MTHF) values in cerebrospinal fluid (CSF) with normal folate concentrations in plasma. Our aim was to analyse CSF 5-MTHF concentrations in a paediatric control population and in patients with various neurological disorders. METHODS: We studied plasma and CSF samples from 63 paediatric controls (age range: 2 days to 18 years, average: 3.8 years) and from 165 patients (age range: 1 day to 22 years, average: 5.0 years) with severe epileptic encephalopathies of unknown origin, movement disorders, Rett syndrome and mitochondrial diseases. CSF 5-methyltetrahydrofolate was analysed by reverse phase HPLC with fluorescence detection (excitation: 295 nm and emission: 355 nm). RESULT: A negative correlation between 5-MTHF values and age of controls was observed (r=-0.468; p<0.0001) and reference values were therefore stratified into 3 age groups. Regarding patients, 122 out of 165 showed normal CSF 5-MTHF values while 43 showed decreased values ranging from profound to mild deficiencies. Increased CSF total protein values were associated with the presence of low 5-MTHF concentrations (chi(2)=7.796; p=0.005). CONCLUSIONS: The application of this method has been useful for the establishment of reference values and for diagnosis of CFD in paediatric patients. Furthermore, increased CSF total protein concentrations should be considered as a marker of a possible CFD.

Deep sedation with propofol in patients with Rett syndrome.

Herein we present the largest retrospective case-control series of deep sedation in patients with Rett syndrome, including discussion of the unique aspects of Rett syndrome that make these patients at high risk for sedation. Twenty-one patients with Rett syndrome and 21 control patients who received propofol for deep sedation to facilitate lumbar puncture were compared. Patients with Rett syndrome required significantly less propofol than control patients when standardized for weight and the duration of the procedure (P = .004). Seven of the 21 patients with Rett syndrome compared with none of the control patients experienced a serious adverse event, most of which were due to prolonged apnea (P = .004). All adverse events were transient, and all patients returned to their baseline after the procedure was completed. Sedation of patients with Rett syndrome is associated with a relatively high rate of complications and should not be done without appropriate personnel available who recognize the risks of sedating this unique population.

Glial fibrillary acidic protein in the cerebrospinal fluid of children with autism and other neuropsychiatric disorders.

The cerebrospinal fluid (CSF) of 47 children and adolescents with autism was analyzed for the contents of two astroglial proteins, the glial fibrillary acidic protein (GFA) and S 100. The results were contrasted with those obtained in similarly aged cases with other neuropsychiatric disorders (n = 25) and in normal children (n = 10). S-100 did not discriminate the groups from each other. However, GFA in autism and autistic-like conditions was at a level almost three times that in the normal group. The results could implicate gliosis and unspecific brain damage in autism. An alternative model would be increased synapse turnover regardless of underlying cause.

Elevated CSF beta-endorphin immunoreactivity in Rett's syndrome: report of 158 cases and comparison with leukemic children.

Because some symptoms of Rett's syndrome are suggestive of excessive endogenous opioid activity, we measured the levels of beta-endorphin-like immunoreactivity in lumbar CSF from 158 affected female patients and from 13 female controls. The mean (+/- SE) control level of beta-endorphin immunoreactivity in CSF was 35.3 +/- 2.8 pg/ml (range, 23 to 48 pg/ml), whereas those with Rett's syndrome had a mean level of 95.3 +/- 3.6 pg/ml (range, 31 to 293 pg/ml). The levels of beta-endorphin immunoreactivity in initial CSF samples exceeded the control range in 90% of the patients with Rett's syndrome. The mean beta-endorphin immunoreactivity was also elevated in CSF from leukemic children (119.2 +/- 16.9 pg/ml; range, 40 to 159 pg/ml), relative to the control group. These results are consistent with the hypothesis that some symptoms of Rett's syndrome may be associated with excessive endogenous opioid levels in the CNS.

Cerebrospinal fluid gangliosides in patients with Rett syndrome and infantile neuronal ceroid lipofuscinosis.

Concentrations of the four major brain gangliosides, GM1, GD1a, GD1b and GT1b, biochemical markers of neuronal membranes, were determined in cerebrospinal fluid from a large series of patients with classical Rett syndrome, aged 1.5-21 years at sampling, and from 11 patients with infantile neuronal ceroid lipofuscinosis, aged 1.5-11 years. The results were compared with age-matched healthy controls. Compared with fluid from the control group, the cerebrospinal fluid samples from Rett patients contained significantly reduced levels of gangliosides GD1a and GT1b. In cerebrospinal fluid of the infantile neuronal ceroid lipofuscinosis patients, even the very young ones, all four major brain gangliosides were significantly reduced compared with controls and the concentration levels also differed significantly from those in patients with Rett syndrome. The ganglioside pattern in the brain is reflected in the cerebrospinal fluid early in the course of the disease in Rett syndrome and infantile neuronal ceroid lipofuscinosis.

CSF beta-endorphin levels in patients with infantile autism.

We measured CSF levels of beta-endorphin, an opioid hormone, in 19 patients with infantile autism and in 3 patients with Rett syndrome, and compared them with control values. In infantile autism, CSF levels of beta-endorphin did not differ significantly from those of age-matched controls. There was no significant correlation between CSF levels and clinical symptoms, including self-injurious behavior, pain insensitivity, and stereotyped movement. However, CSF levels of beta-endorphin were significantly higher in the patients with Rett syndrome than in the control (p < .05). Data suggest that neurons containing beta-endorphin may not be involved in patients with infantile autism. Thus, there is no relationship between dysfunction of brain opioid and autism.

Low levels of nerve growth factor in cerebrospinal fluid of children with Rett syndrome.

A role of neurotrophic factors has been postulated in some human neurodegenerative disorders such as Alzheimer's and Parkinson's disease. The known developmental effects of these substances suggested that, in some neurologic diseases affecting children, neurotrophic factors might be inadequate. Using a sensitive, two-site enzyme-linked immunoassay, we examined the content of nerve growth factor in the cerebrospinal fluid of 11 children with Rett syndrome and of 24 control patients with various neurologic diagnoses or suffering from other diseases. Nerve growth factor levels were significantly lower in the cerebrospinal fluid of the patients with Rett syndrome than in control patients. The lower level of cerebrospinal fluid nerve growth factor in Rett syndrome suggests that lack of nerve growth may be involved in the pathogenesis of this disease or reflect the underlying brain damage present.

Cerebrospinal fluid beta-endorphin and cortisol study in Rett syndrome.

An evaluation of cerebrospinal fluid and plasma beta-endorphin and cortisol levels was performed in 15 girls affected with classic Rett syndrome. There were no differences between the patient group and the control group in plasma cortisol and beta-endorphin levels. But in Rett syndrome, a significant increase in beta-endorphin was noted in the cerebrospinal fluid, with an elevation of the cerebrospinal fluid/plasma beta-endorphin ratio and a decrease in cerebrospinal fluid cortisol. A substantial overlap between patients and control group diminishes the diagnostic value of cerebrospinal fluid beta-endorphin assay in girls suspected of having Rett syndrome.

Abnormal carbohydrate metabolism in cerebrospinal fluid in Rett syndrome.

We analyzed lactate, pyruvate, and citric acid cycle intermediates in cerebrospinal fluid by high-performance liquid chromatography in Rett syndrome patients (n = 27; mean age, 5.7 +/- 3.4 years) and age-matched female controls (n = 12; mean age, 7.0 +/- 3.3 years). The lactate, pyruvate, alpha-ketoglutarate, and malate were significantly elevated in Rett syndrome compared to the controls. The lactate/pyruvate ratio was not different. On the other hand, cerebrospinal fluid citrate, cis-aconitate, succinate, fumarate, and oxaloacetate were not significantly different in Rett syndrome patients than in the controls. We also evaluated the correlation between these acids and clinical symptoms and signs, including clinical stage, seizures medications (anticonvulsants or naltrexone), developmental quotient, self-abuse, and hyperventilation or apnea or both. The concentrations of all these acids did not differ significantly with clinical stage. Lactate elevation significantly correlated with apnea. Lactate and pyruvate elevation significantly correlated with hyperventilation or with both breathing abnormalities. Our observations in this sample of patients with Rett syndrome led us to speculate that patients with the Rett syndrome may have defective carbohydrate metabolism. Elevated mitochondrial reduced nicotinamide-adenine dinucleotide-linked substrates suggest that reduced nicotinamide-adenine dinucleotide-ubiquinone oxidoreductase may be deficient in the brain in Rett syndrome patients.

Neurotrophic factors in the pathogenesis of Rett syndrome.

Rett syndrome is characterized by disruption of a period of vigorous brain growth with synapse development. Neurotrophic factors are important regulators of neuronal growth, differentiation, and survival during early brain development. The aims of this study were to study the role of neurotrophic factors in Rett syndrome, specifically whether Rett syndrome has abnormal levels of specific neurotrophic factors in serum and cerebrospinal fluid and whether the changes differ from other neuropediatric patients, for example, those with infantile autism. Four neurotrophic factors were measured: nerve growth factor, brain-derived neurotrophic factor, glial cell line-derived neurotrophic factor, and insulin-like growth factor 1 from the frozen cerebrospinal fluid and from serum (except glial cell line-derived neurotrophic factor) by enzyme-linked immunosorbent assay and cerebrospinal fluid glutamate and aspartate by high-performance liquid chromatography (HPLC) method in patients with Rett syndrome. Insulin-like growth factor 1 was measured from the cerebrospinal fluid of patients with infantile autism. We found low concentrations of cerebrospinal fluid nerve growth factor in patients with Rett syndrome compared with control patients. The serum levels and other cerebrospinal fluid neurotrophic factor levels of the patients did not differ from the controls. Patients with Rett syndrome had high cerebrospinal fluid glutamate levels. Patients with infantile autism had low cerebrospinal fluid insulin-like growth factor 1 levels. Nerve growth factor acts especially on cholinergic neurons of the basal forebrain, whereas insulin-like growth factor 1 acts on cerebellar neurons. In Rett syndrome, the forebrain is more severely affected than the other cortical areas. In autism, many studies show hippocampal or cerebellar pathology. Our findings are in agreement with the different morphologic and neurochemical findings (brain growth, affected brain areas, neurotransmitter metabolism) in the two syndromes. Impairment in dendritic development in Rett syndrome could be the consequence of cholinergic deficiency and of neurotrophic factor/glutamate imbalance. Cholinergic gene expression might be influenced by the Rett syndrome gene directly or via the neurotrophic factor system.

Low CSF HVA levels in the Rett syndrome: a reflection of restricted synapse formation?

The concentration of neurotransmitter metabolites in the CSF was determined in 10 girls with the Rett syndrome (RS) (age range 5.8-17.2) and in 14 control children (age range 4.5-16.7) treated for acute leukemia without signs of CNS involvement. Homovanillic acid concentration decreased with age in both groups. The decrease was less steep in RS compared to controls, with lower concentrations in young girls and normal concentrations at 15 years of age. 5-hydroxyindoleacetic acid decreased proportionally in both groups. It is suggested that the low concentration of HVA in young girls reflect deficient multiplication of catecholaminergic synapsis.

Cerebrospinal fluid studies in the Rett syndrome: biogenic amines and beta-endorphins.

The etiology of the Rett syndrome (RS) is unknown. Reduced function of biogenic amines has been described. Symptoms of central apnea, hyperventilation, hypothermia, peripheral analgesia, muscle rigidity, myoclonic jerks, hand stereotypy and seizures occur in RS and have been suggested as a result of elevated central beta-endorphins. It was hypothesized that a dysfunctional modulation of endogenous opiate systems and biogenic amines may be present. Cerebrospinal fluid (CSF) from 12 girls with RS was studied for beta-endorphin immunoreactivity, and biogenic amines. Lactates and pyruvate levels were measured. Eleven of the 12 girls had elevated beta-endorphin immunoreactivity in CSF, 4 girls had reduced biogenic amines and 6 girls had elevated pyruvate and lactate levels. Whether the elevated beta-endorphin immunoreactivity is a primary disorder or is a result of secondary feedback mechanisms is unknown. Naltrexone, an antiopioid drug, may reduce symptoms.

The Rett syndrome and CSF lactic acid patterns.

We investigated both blood and cerebrospinal fluid (CSF) lactate and pyruvate levels in seven girls with the Rett syndrome (RS) and evaluated the relationship between CSF lactate and pyruvate levels and the clinical manifestations, particularly seizures, anticonvulsant medication, and breathing dysfunction including breath holding, apnea and hyperventilation. Elevated lactate and pyruvate levels in CSF with normal serum lactate were found in two RS patients. Elevated CSF lactate correlated significantly with the clinical occurrence of hyperventilation (P0 = 0.048, Fisher exact probability). We measured native and dichloroacetate (DCA)-activated pyruvate dehydrogenase (PDH) complex activities in two patients (#1 and 2) using cultured lymphoblastoid cell lines which were transformed by EB virus and the results were normal. We also analyzed CSF citric acid intermediates from 7 RS patients including citric acid, cis-aconitate, alpha-ketoglutarate, succinate, fumarate, malate and oxaloacetate. These concentrations were not significantly different from those control patients (N = 21). An elevated lactate level may be a clue to clarify the etiology of RS.

Elevated CSF lactate in the Rett syndrome: cause or consequence?

We report values for CSF and blood lactate and acid-base balance in 8 girls with the Rett syndrome and correlate the findings with respiratory dysfunction. Three patients had elevated CSF lactate values; their hyperventilation (HV) was so intensive that the acid-base balance showed respiratory alkalosis with an abnormally low base excess. One of these three patients had normal CSF lactate and acid-base balance before she developed HV. Two patients were so young that they had not yet developed HV and their CSF lactate values were normal. One patient had elevated CSF lactate when she was younger and her HV was more intensive, but now her CSF and blood lactate were normal; her acid-base balance showed mild hypocapnia but was otherwise normal. Thus, in the Rett syndrome, CSF lactate elevation seems to be a secondary phenomenon connected with the intensive HV and alkalosis rather than a sign of any mitochondrial disorder.

CSF beta-endorphins in childhood neuropsychiatric disorders.

Thirty-one children with autistic disorder, 8 with the Rett syndrome (RS), 2 with childhood disintegrative disorder and 5 with infantile spasms were compared with healthy adult controls with respect to cerebrospinal fluid (CSF) beta-endorphin levels. The autistic disorder and RS groups showed significantly lower values than the other groups. There were no age trends within the various groups. Further study of CSF beta-endorphins in these disorders and blindly examined age matched controls is warranted.

Four adult Rett patients at an institution for the handicapped.

We report the clinical, laboratory, and magnetic resonance imaging results of 4 adult patients (ages 25, 26, 29, and 35 years) with stage IV Rett syndrome. The patients were diagnosed at an institution for the handicapped. Two of them had been previously diagnosed as having cerebral palsy. All were microcephalic and had seizures, although the frequency of seizures decreased with advancing age. Three patients had scoliosis. Magnetic resonance imaging demonstrated marked craniofacial disproportion in 2 patients, bilateral atrophy of the frontotemporal lobes in 3, and cerebellar atrophy in 1. The cerebrospinal fluid concentrations of biopterin and homovanillic acid did not differ significantly in these Rett syndrome patients from age-matched controls.

High levels of cerebrospinal fluid glutamate in Rett syndrome.

Rett syndrome is a neurodevelopmental disease affecting girls. The cause is not known. Roles for trophic factors and excitatory neurotransmitters have been postulated. To study the significance of excitatory amino acids in Rett syndrome, we determined glutamate and aspartate concentrations in the cerebrospinal fluid from 11 girls with Rett syndrome (age 8 years 4 months +/- 5.7 years, mean +/- SD) and 11 controls (age 7 +/- 4.2 years). In the patients with Rett syndrome, the mean of cerebrospinal fluid glutamate concentration was 355.2 nmol/L (SD +/- 109.2 nmol/L). In the controls it was 203.9 nmol/L (SD +/- 55.5 nmol/L). In Rett syndrome cases, cerebrospinal fluid glutamate concentrations were significantly higher (P = 0.0006) than in the controls. In the Rett syndrome group, the mean cerebrospinal fluid aspartate concentration was 119.4 nmol/L (SD +/- 43.5 nmol/L). In the control group, it was 90.9 nmol/L (SD +/- 20.9 nmol/L). The difference between the cerebrospinal fluid aspartate values was not significant. Glutamate may therefore play an important role in the primary pathogenesis in Rett syndrome. Further investigations are needed, with recognition of possible actions of neuronal growth factors and excitatory neurotransmitters in the damage mechanisms of Rett syndrome.

Developmental aspects of cerebrospinal fluid levels of beta-phenylethylamine and it's role in pediatric neurological disorders.

To clarify the role of beta-phenylethylamine (PEA) in pediatric neurological disorders, we have measured the cerebrospinal fluid (CSF) levels of PEA in 12 children with aseptic meningitis--6 were in the acute phase and the other 6 were in the recovery phase--and 5 children with Rett Syndrome (RS). The findings were compared with those obtained from 13 age-matched children with leukemia as child controls and from 10 adults patients without any neurological symptoms and signs as control. In the control group, the CSF PEA level was negatively correlated with age until 200 months (17 years) old. The mean PEA levels in meningitis and RS were significantly lower than that of child controls (p < 0.03). The alteration in the CSF levels of PEA may be related to transient changes in the dopaminergic tone in aseptic meningitis and neurological impairment, especially in the dopaminergic neurons in RS.