Measurement of spontaneous rotational movement (circling) in normal children

An asymmetry of basal ganglia dopaminergic function has been demonstrated in rats and related to both spontaneous and drug-induced rotation. An electronic device that measures the same kind of rotational movements in humans has been developed, and we have utilized this "rotometer" to study spontaneous rotational movement in prepubertal children. There was no significant difference between boys and girls in their average rate of rotation; however, left hemisphere-dominant boys were stronger rotators than left hemisphere-dominant girls. Both boys and girls made significantly more full turns to the left than to the right. These findings did not vary with age. Our observations are strikingly different from those obtained in previous studies of normal adults, in which women were stronger rotators than men, left hemisphere-dominant women turned to the left, and left hemisphere-dominant men rotated to the right. This study suggests that maturational changes in rotational behavior must occur, perhaps progressing to the adult pattern during puberty. The rotometer used in this study may provide useful information regarding the status of the basal ganglia in children with specific neurobehavioral conditions such as attention deficit disorder and Tourette's syndrome.

Familial X-linked myalgia and cramps: a nonprogressive myopathy associated with a deletion in the dystrophin gene

We report a family with an X-linked recessive disorder characterized by muscle cramps and myalgia. Nine affected male family members had high resting serum levels of creatine kinase, and well-developed musculature with calf hypertrophy but no evidence of muscular weakness. Symptoms began in childhood and did not progress. Electromyographic findings were consistent with myopathy while muscle biopsies showed nonspecific myopathic changes without evidence of storage of glycogen or lipid. Analysis of DNA revealed a deletion in the 1st third of the dystrophin gene. Western blot analysis revealed that dystrophin was smaller than that in normal samples, with no reduction in the amount of the protein present. This disorder represents a new clinical phenotype associated with a deletion in the dystrophin gene. This deletion affects a portion of the dystrophin molecule that clinically does not appear to significantly alter its function. Other patients with deletions in this region may have truncated dystrophin without clinical signs of progressive muscle disease.

Hereditary long Q-T syndrome presenting as epilepsy: electroencephalography laboratory diagnosis

Patients with hereditary Q-T interval prolongation can present with seizures, syncope, and sudden death. In 2 siblings with autosomal dominant familial long Q-T syndrome, electroencephalographic examinations performed 6 and 2 years before diagnosis included electrocardiographic tracings documenting the cardiac abnormality. A timely diagnosis of this condition may have prevented the death of 1 of these patients. Measurement of the corrected Q-T interval on electrocardiographic tracings obtained in the electroencephalography laboratory should be considered in selected patients.

Acute vincristine neurotoxicity in the presence of hereditary motor and sensory neuropathy type I

Acute vincristine neurotoxicity leading to a severe motor and sensory neuropathy has been noted in patients with hereditary motor and sensory neuropathy type I (HMSN-I). The case of a 2-year-old boy with acute lymphocytic leukemia and HMSN-I is reported, and additional cases from the literature are reviewed. Severe vincristine neurotoxicity in patients with HMSN-I may be secondary to impairment of both slow and- fast axonal transport. Vincristine should be used with caution in patients with a family history of polyneuropathy.

Myeloradiculopathy associated with wasp sting

A 12-year-old girl developed a reversible myeloradiculopathy 1 week after a wasp sting. Delayed neurologic hypersensitivity reactions to Hymenopteran stings occur primarily in adults. Reactions involving both the peripheral and central nervous systems are extremely rare and have never been reported in a child. The mechanisms underlying this uncommon reaction may be related to age-dependent differences in immunologic responses.

Central nervous system distribution of inhaled toluene

The regional central nervous system distribution of inhaled [14C]toluene was studied in the rat. Toluene was detected in all brain regions, with the highest concentrations in the brainstem. The initial uptake of toluene was significantly correlated with the total lipid content of each brain region. Clinical and experimental neurotoxicity of toluene may be due, in part, to an increased concentration of this solvent in lipid-rich brain areas.

Nemaline myopathy associated with hypertrophic cardiomyopathy

Nemaline myopathy is not usually considered to involve cardiac muscle and rarely is associated with nocturnal hypoventilation. We report a boy, 5 1/2 years of age, with nemaline myopathy who presented with respiratory failure. Echocardiography demonstrated the septum to left ventricular posterior wall ratio to be increased which is consistent with a hypertrophic cardiomyopathy. Because of nocturnal hypoventilation, tracheostomy was placed for ventilatory assistance. A process involving both muscle and nervous tissue may underlie this congenital myopathy; routine cardiac and pulmonary function evaluations may be indicated in these patients.

Life-threatening congestive heart failure as the presentation of centronuclear myopathy

Myocardiopathy is associated infrequently with centronuclear myopathy. We present biopsy studies of a 15 1/2-year-old black male who presented with profound acute congestive heart failure and diffuse muscular atrophy. Cardiac symptoms had been present for 6 months; limb weakness had been unassociated with either infantile hypotonia or developmental delay. Cardiac catheterization demonstrated a dilated myocardiopathy and poor left ventricular contractility. Biopsies of both ventricles revealed striking hydropic degeneration and fibrosis. Right triceps biopsy disclosed centronuclear myopathy. Because the spectrum of disease expression in centronuclear myopathy is extensive, an association with cardiac disease always should be considered in these patients. In addition, we recommend that patients who present with idiopathic myocardiopathy should be evaluated for this and other skeletal muscle diseases.

Infantile spasms following near-drowning: a report of two cases

We report the occurrence of infantile spasms following near-drowning in two children with previously normal development. In both cases, the episode of near-drowning occurred well after the 1st year of life, and the age at onset of spasms (20 and 34 months, respectively) was unusually late. The possible significance of these two cases in relation to the pathophysiological mechanism underlying infantile spasms is briefly discussed.

Drug-induced dystonia in neuronal ceroid-lipofuscinosis

Neuroleptic-induced tardive dystonia is frequently refractory to therapy. We describe a 13-year-old girl with neuronal ceroid-lipofuscinosis who developed dystonia after beginning treatment with thioridazine for acute psychosis. Although anticholinergic drugs and benzodiazepines were ineffective, the patient improved with baclofen. Patients with certain degenerative diseases of the central nervous system may be at increased risk for the development of drug-induced dystonia, and we caution against the use of neuroleptics in these patients.

Studies of dopamine pharmacology in molluscs

Dopamine has been established as a putative neurotransmitter in several species of molluscs. Biochemical and neurophysiological studies of the cellular pharmacology of dopamine have revealed several properties of molluscan dopamine receptors. The biochemical synthesis and degredation of dopamine in molluscs follows the same pathways that have been described in mammals. Adenylate cyclase is present, and the receptor mediating CAMP production is blocked by neuroleptics and certain ergot alkaloids. Studies of this enzyme and of radioligand binding indicate that molluscan dopamine receptors and serotonin receptors share certain characteristics. Neurophysiological studies have shown that dopamine induces several forms of ionic conductance changes in molluscan neurons. The receptors mediating these conductance changes may be differentiated pharmacologically. Neuroleptics are antagonists at certain receptors and ergot alkaloids have been shown to be either partial agonists or antagonists. Present evidence indicates that molluscan and mammalian CNS dopamine receptors have some similarities. However, further biochemical and neurophysiological investigations will be necessary to fully characterize molluscan dopamine receptors.

Pharmacological studies of a novel dopamine-sensitive receptor mediating burst-firing inhibition of neurosecretory cell R 15 in Aplysia californica

Burst-firing activity of neuron R 15 in the abdominal ganglion of Aplysia californica is inhibited by dopamine (DA) (50-500 microM). By using voltage clamp analysis of agonist-induced reduction of inward current and bath application of pharmacological agents, the agonist and antagonist specificity of the receptor mediating burst-firing inhibition in this cell was studied. The phenethylamine compounds DA, epinine, (-)-norepinephrine, (+)-norepinephrine, (-)-epinephrine, (+)-epinephrine and (-)-phenylephrine are active at similar concentrations. DA analogs 2-amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene HBr and 2-amino-5,6-dihydroxy-1,2,3,4-tetrahydronaphthalene HBr are active, whereas apomorphine, piribedil, (3,4-dihydroxyphenylamino)-2-imidazoline HCl and RU 24213 are inactive. DA-mediated inhibition of burst-firing is not antagonized by neuroleptics or certain adrenergic antagonists. Antagonism is seen with dihydroergotamine, lysergic acid diethylamide, ergonovine and other ergot alkaloids and the complex nature of this antagonism is discussed in detail. The specificity of this receptor for agonists and antagonists is compared to DA and adrenergic receptors from mammalian and other invertebrate tissues. We conclude that this DA-sensitive receptor mediating burst-firing inhibition of cell R 15 in Aplysia californica is very different from DA and adrenergic receptors.

Dopamine inhibits burst-firing of neurosecretory cell R 15 in Aplysia californica: establishment of a dose-response relationship

Burst-firing in neurosecretory cell R 15 of Aplysia californica is inhibited by the bath application of dopamine. Voltage-clamp analysis reveals a complex series of changes in the current-voltage relationship of R 15. Dopamine reduces the inward current in the region of negative slope conductance and tends to linearize the current-voltage curve. A variable increase in potassium conductance is frequently observed. The loss of inward current in the region of negative slope conductance is dose-dependent, highly reproducible and relatively resistant to desensitization, and for these reasons a valid dose-response relationship can be described. The dose-response curve is sigmoidal in shape and rises from a minimal effect near 50 microM to a maximal effect near 500 microM. This dose-response curve is useful as a standard of comparison in studies of agonists and antagonists. A protocol for the quantitative study of this system is described, and the constellation of changes in the current-voltage curve produced by dopamine is discussed.