Disturbances in neuronal migration and laminar cortical organization associated with multicystic encephalopathy in the Pena-Shokeir syndrome

Fetal akinesia deformation sequence with delayed skeletal muscle maturation and polymicrogyria: evidence for a hypoxic/ischemic pathogenesis

Multiple congenital contractures, also known as fetal akinesia deformation sequence (FADS) and related terms, result from decreased fetal movement. The underlying etiologies are diverse and include central nervous system (CNS) dysgeneses and primary myopathies. Persistent central nuclei or the presence of myotubes is often regarded as evidence of a primary myopathic etiology; however, these findings are also associated with impaired fetal innervation. We report 7 fetuses, estimated gestational age 20 to 23 weeks, with persistent myotubular morphology, a change that could be (mis)interpreted as a primary myopathy. In 4 of the patients, CNS histology showed hypoxic/ischemic injury, polymicrogyria, mineralized neurons, and microinfarcts with or without loss of anterior horn neurons. FADS cases with polymicrogyria have frequently been interpreted as a consequence of a primary brain malformation. Only a few descriptions of FADS associate polymicrogyria with CNS hypoxic/ischemic injury, however, and do not describe skeletal muscle maturation delay. We hypothesize that this combination of neural and muscular pathology is an under-recognized pattern in FADS, which results from diffuse hypoxic/ischemic injury involving the brain and spinal cord during early to middle gestation.

Pena-Shokeir phenotype (fetal akinesia deformation sequence) revisited

BACKGROUND

Pena and Shokeir described the phenotype of two sisters in 1974, and subsequently their features have become recognized as a sequence of deformational changes related to decreased or absent fetal movement (fetal akinesia deformation sequence [FADS]), because of the work of Moessinger (1983).

METHODS

Identification of reported cases by searching Online Mendelian Inheritance in Man, Medlines, the London Dysmorphology Database, and the references found in these articles. These case reports were reviewed, tabulated, and summarized.

RESULTS

It is now possible to recognize at least 20 familial types of Pena-Shokeir phenotype (PSP), based on the differences found in the reports of the natural history and pathology found at fetal and newborn autopsy. In addition, characteristic changes in the central nervous system seen with embryonic/fetal vascular compromise have been recognized in many reported cases. Most of the reported cases of PSP/FADS related to vascular compromise are sporadic, but familial cases have also been reported.

CONCLUSION

Lack of fetal movement (fetal akinesia) in humans produces a recognizable sequence of deformations. Many developmental processes must be accomplished for fetal movement to be normal, and for extra-uterine life to be sustainable. Prenatal diagnosis is possible through real-time ultrasound studies as early as 12 weeks. Most reported cases die in utero, at birth, or in the newborn period. Advances in embryo/fetus pathology have led to the recognition of the many familial subtypes, allowing improved genetic counseling and early recognition in subsequent pregnancies.

Prenatal stroke

The main focus of this chapter is the comprehensive description of the neuropathology, the imaging correlates and underlying mechanisms of prenatal stroke. We describe established prenatal stroke in subgroups similar to postnatal stroke: arterial (forebrain or hindbrain) infarction, venous thrombosis, primary lobar haemorrhage. This longitudinal classification should facilitate the study of risk factors and mechanisms. Forebrain lesions of arterial type present as porencephaly, (hemi)hydranencephaly, multicystic encephalopathy or schizencephaly. Venous prenatal forebrain stroke presents as simple porencephaly (in some of genetic nature) and sinus thrombosis. A list of rare porencephaly-like conditions is added for differentiation from arterial and venous porencephaly. Hindbrain infarctions (so far the only reported variants seem to be of arterial nature) present as brainstem disconnection, focal brainstem destruction, uni- or bilateral cerebellar destruction and focal spinal cord ischaemia. Prenatal intracranial haemorrhage and congenital brain infection should be considered in the differential diagnosis of prenatal stroke.

Olfactory bulb dysplasia: a novel subtype of neuronal migration disorder

We present a novel subtype of neuronal migration disorder found in a case of Pena-Shokeir phenotype, in which the deformation sequence originated from neurogenic fetal akinesia. The autopsied brain showed dysplastic features of dentate and olivary nuclei as well as a bilaterally enlarged olfactory bulb with abnormal laminar structures. The laminar structures comprised four layers: (1) a superficial layer without glomeruli, (2) a neuronal cell layer containing neurons simulating mitral cells, (3) a sparse cell layer enriched with tangential neuronal fibers, and (4) a reticular layer showing a mottled appearance with the accumulation of fine reticular neurites intermingled with granule cells. To our knowledge, these malformed laminar changes have never been reported, and we propose the term olfactory bulb dysplasia.

Pena-Shokeir phenotype associated with bilateral opercular polymicrogyria

Autopsy examination of an infant with the Pena-Shokeir phenotype revealed bilateral opercular polymicrogyria associated with neuronal loss and ferrugination in the basal ganglia, thalamus, brainstem, and spinal anterior horns. Bilateral opercular polymicrogyria previously has been linked to the developmental form of Foix-Chavany-Marie syndrome, or faciopharyngoglossomasticatory diplegia. In the Pena-Shokeir phenotype, bilateral opercular polymicrogyria may contribute to deficits in swallowing and facial movements. The pattern of brain and spinal cord injury in this case supports previous suggestions that the Pena-Shokeir phenotype (and certain other forms of arthrogryposis multiplex congenita) may be caused by hypoxic-ischemic injury to the developing central nervous system.

Lethal arthrogryposis multiplex congenital (fetal akinesia deformation sequence, FADS)

Arthrogryposis multiplex congenital (AMC) is the presence at birth of multiple congenital contractures in an intact skeleton. The severity of the condition is highly variable and the possible underlying causes are numerous. Fetal immobility and lesions of the brain, spinal cord, peripheral nerves and muscle, along with mechanical restriction of the fetus in utero are the pathogenic mechanisms that need to be considered. Etiological factors that have been implicated in the development of AMC include genetic conditions, infections, drugs, toxins, maternal hyperthermia, and maternal illness. This review will concentrate on the severe end of the spectrum of AMC that results in disease that is lethal pre- or postnatally, and will discuss the pathology, pathogenesis, etiology, and practical approach to this diversely expressed condition.

Two cases of fetal akinesia/hypokinesia sequence

Two cases of fetal akinesia sequence are described. Both showed facial anomalies, arthrogryposis multiplex, bilateral camptodactyly, and pulmonary hypoplasia. One child had degeneration of large motor neurons of the thoracolumbosacral spinal cord and irregular atrophy of diaphragm; the other had left microphthalmia, hemiatrophy of the left temporal lobe with calcification of degenerated neurons, and hypoplasia of the cervothoracic spinal cord with decrease and degeneration of neurons. The iliopsoas and intercostal muscles showed focal myofiber atrophy. These findings suggested that some instances of this fetal akinesia syndrome might be due to neuromuscular dysfunction that occurred in utero and may have various causes.

Skeletal muscular changes in Pena-Shokeir sequence

Histologic examination of the skeletal muscles in 8 fetuses and newborn patients with the Pena-Shokeir sequence revealed only minor nonspecific changes which could not be ascribed to any of the well defined myopathies. Muscle fiber diameters were increased in 2 out of 5 patients examined. No significant malformations of inner organs were found at autopsy. It is concluded that fetal hypokinesia due to skeletal muscular lesions might be responsible for both the pulmonary hypoplasia and the deformations of the face and extremities in all cases of this investigation.

Pena-Shokeir phenotype with major CNS-malformations: clinicopathological report of two siblings

Clinical and pathological features of two siblings of opposite sex with the Pena-Shokeir phenotype are reported. A detailed account of the prenatal and dysmorphological findings is given in one case. A broad range of deformations regarded as secondary to fetal hypokinesia was present, including a number of yet unreported findings. One case showed additional endocrine hyperplasia and left lung trilobation. Both siblings displayed extensive, highly similar CNS-abnormalities. The type and convergence of these malformations differ from previously reported cases and characterize a new familial subtype of the Pena-Shokeir phenotype.

Pena-Shokeir phenotype in sibs with macrocephaly but without growth retardation

A number of more or less distinct subgroups with the Pena-Shokeir phenotype have been identified. We studied two brothers with the Pena-Shokeir phenotype who were unusual because they had macrocephaly and normal growth. In the second sib, no neuromuscular abnormalities were found at autopsy. Among the subgroups with Pena-Shokeir phenotype, these sibs resemble the family reported by Ohlsson et al. [1988] more than the other subgroups that have been proposed. In addition, abnormalities were detected by prenatal ultrasonography during the 18th week of gestation of the second fetus. This finding provides additional evidence that this phenotype may be detected early enough in gestation to consider intervention.

A syndrome of multiple congenital contractures: neuropathological analysis on five fetal cases

We performed a neuropathological study on 5 fetuses with an autosomal recessive, lethal syndrome of congenital contractures diagnosed by fetal hydrops on ultrasonography. The fetuses showed a typical pattern of malpositioning of hips and knees with occasional pterygia of the neck and elbows. The muscles were hypoplastic and the spinal cords showed severe thinning, most markedly affecting the ventral half. A total loss of axons in the ventral and lateral funiculi, subtotal loss of anterior horn motor neurons with accompanying astrocytosis and astrogliosis, and similar but less severe changes at the brain stem level suggested a degenerative rather than a dysmorphogenetic mechanism. Sensory nuclei and pathways were distinctly less severely affected, if at all. The findings further delineate this condition as a genetically and pathoanatomically distinct autosomal recessive syndrome.

Prenatal diagnosis of a new syndrome: holoprosencephaly with hypokinesia

Markedly decreased fetal activity (akinesia/hypokinesia) is usually readily apparent to experienced mothers, and frequently this concern leads to attempts at prenatal diagnosis. We report prenatal diagnosis of two fetuses with congenital contractures, markedly decreased fetal movement, and microcephaly due to severe holoprosencephaly. Such familial recurrence to phenotypically normal parents suggests a newly recognized autosomal recessive or X-linked syndrome that is readily detectable by prenatal ultrasonography.