X-linked infantile spinal muscular atrophy.

Four male infants from three sibships in an extended family were noted to have hypotonia, areflexia, and congenital joint contractures. The findings of electromyography and muscle histology were consistent with infantile spinal muscular atrophy (SMA). Pedigree analysis suggests that this disorder represents an X-linked, recessive form of SMA. Findings in similar kindreds may explain the previously reported increased male-female ratio in infantile SMA.

Brainstem subarachnoid respiratory epithelial cysts: report of two cases and review of the literature.

Two cystic lesions that were lined by pseudostratified ciliated columnar epithelium containing goblet cells are described. Both lesions were found in the subarachnoid space between the vertebrobasilar arterial system and the brainstem. One cyst was an incidental finding in a patient who died of orbital phycomycosis. The cyst was filled with clear mucinous material. The second cyst presented as a mass adjacent to the brainstem in a woman who had progressive brainstem dysfunction. This lesion showed transition from pseudostratified ciliated columnar epithelium with goblet cells to papillary stratified squamous epithelium, histologic features essentially identical to those of squamous papillomas of the nasal cavity. This lesion was filled with squamous debris. The proposed origin of these lesions is discussed.

Murine forebrain anomalies induced by coxsackievirus B3 variants.

Neonatal or 7-day-old mice inoculated intracranially with either of two temperature-sensitive mutants (ts1, ts6) or the parent coxsackievirus B3 (CVB3) subsequently developed porencephaly or hydranencephaly. The forebrain anomaly induced depended upon age of the animal at inoculation and virus variant inoculated. Sections of brains from hydranencephalic mice revealed severe meningeal reactions, necrotizing encephalitis, and liquifactive necrosis in the cerebrum. No pathology was found in the pons, medulla, or cerebellum. Immunofluorescence studies with hyperimmune anti-CVB3 antiserum showed a random distribution of virus-infected cells in the cerebrum. Virus was recovered from several organs but little to no interferon and no anti-CVB3 neutralizing antibody were present in brain tissues. Availability of cells for replication of virus at the time of inoculation and replicative properties of each virus likely contributed to the outcome. Thus, forebrain anomalies resembling those found in infants can be induced in a murine model by select variants of coxsackievirus B3.

Localized eosinophilic myositis of the masseter muscle associated with actinomycosis.

A case of eosinophilic myositis of the masseter associated with pseudotumor and trismus is presented. Extensive eosinophilic infiltrates of the masseter are rarely observed in the absence of parasitic infection or the hypereosinophilic syndrome. This case is reported because of the rarity of the phenomenon and its importance to the surgeon from the standpoint of differential diagnosis and treatment. The pathogenesis of the condition and its relation to other lesions of muscle associated with eosinophilic infiltration are discussed.

Morphogenesis of experimental anencephaly.

The sequential morphological development of anencephaly was studied in an experimental model. Vitamin A was administered to pregnant rats on gestational days 8, 9, and 10. When the litters were allowed to proceed to term, the treatment resulted in fetuses with anencephalic features. The progressive morphological development of the malformation was then established by histological and gross study of embryos and fetuses of different ages. The earliest lesion identified was a microfocal necrosis located in the head fold epithelium near the anterior neuropore on day 9; it was lateral to the normal position of physiological necrotic foci seen in control embryos. Subsequent to the appearance of the initial lesion, the malformation developed as everted brain folds extending vertically from the diencephalon in the pattern of exencephaly. The neural tube in the region of the malformation never closed, and the exencephaly arose as a progressive development of non-closed neural tube. Finally, the classical anencephalic resulted from the spontaneous necrosis of the exencephalic malformation. This study indicates that anencephaly in an experimental model arises from microscopic foci of necrosis near the anterior neuropore and develops through non-closure of the neural tube.

Effect of the dural application of Zenker's solution on the feline brain.

Zenker's solution is a tissue fixative containing mercuric chloride, potassium bichromate, sodium sulfate, and glacial acetic acid. In 1956, Anderson and Johnson reported its use in clinical neurosurgery. They applied the solution to the exposed dura after craniectomy. Delayed bone formation was thought to be due to the suppression of the osteoblastic activity of the outer layer of the dura. The fixative has since become a well-accepted adjuvant to the treatment of craniosynostosis. In 1972, Pawl and Sugar reported postoperative seizures in 6 of 34 patients treated with this solution. They assumed that the fixative penetrated the dura and irritated or damaged the cortex. To clarify the effect of Zenker's solution on the underlying brain, we performed bilateral parasagittal craniectomies in a group of kittens and adult cats. Zenker's solution was applied to one side and the other side served as a control. The animals were killed after periods varying from 24 hours to 2 months. We then examined the cortex under the craniectomies. There was immediate breakdown of the blood-brain barrier, as evidenced by the penetration of intravenous Evans blue. In the postoperative period investigated, an inflammatory response in the underlying brain with thickening of the arachnoid occurred. The results and implications of these experiments are presented. (Neurosurgery, 6: 45--48, 1980)

Rhabdomyosarcoma arising in a pineal teratoma.

Pineal teratomas are relatively uncommon intracranial neoplasms. A rhabdomyosarcoma developed in a pineal teratoma in a 14-year-old boy and was rapidly fatal despite radiation therapy. This is the second reported case of a pineal teratoma giving rise to a rhabdomyosarcoma.

Experimental dysraphism in the rat.

An experimental treatment that results in dysraphic lesions in rat embryos was studied to gain insight into the origin of such lesions. Pregnant rats given 100,000 units of vitamin A by gavage tube on gestational Days 8, 9, and 10 produced abnormal litters, and 50% of the embryos had exencephaly and/or spina bifida. Study of these embryonic lesions revealed hyperplesia of neural tube tissue that extended laterally to the edge of an epidermal defect. The epidermal defect consisted of the absence of fetal epidermis over the hyperplastic neural tissue. At no stage in development was embryonic hydrocephalus noted. In fact, the central canals of the embryos with malformations were poorly developed and smaller than those of control embryos. Results with this model indicate that the malformations arise through a process of overgrowth and hyperplasia and not from embryonic hydrocephalus. Continued work with this and other models is required to delineate new mechanisms and to offer alternative postulates for the origin of dysraphic lesions.

Inverse cerebellum and occipital encephalocele. A dorsal fusion defect uniting the Arnold-Chiari and Dandy-Walker spectrum.

The malformation of inverse cerebellum and occipital encephalocele is situated morphologically between the Arnold-Chiari and Dandy-Walker malformations. In the three reported cases, hydrocephalus was not present, concomitant malformations of the lamina terminalis were present in two, and polymicrogyria was found in all three. The primary defect in the malformation is a complex occipital encephalocele composed of miniature hemispheres connected to the brain stem by an extension of the midbrain tectum. The cerebellar folia extend ventrally and cover the basilar artery. We propose that the encephalocele arises through the processes of overgrowth and dysraphism and thus falls into the organogenetic malformations of Yakovlev. Supporting this theory is the consistent observation of the duplicate hemispheres in the encephalocele and the hydromyelia in the examined spinal cords.