ABSTRACT
Achondroplasia, a skeletal dysplasia has an incidence of 1 in 15000 to 1 in 30000 live births. It is inherited in an autosomal dominant manner. The occurrence of recurrent achondroplasia in babies born to normal parents is rare. The present case report is one such type. A female fetus of 27 weeks gestational age was brought to the Department of Anatomy, Karpaga Vinayaga Institute of Medical Sciences, Maduranthagam. There was frontal bossing of forehead, rhizomelic type of limb shortening with limitation of elbow extension in the fetus. The mother of the fetus, who is 26 years old, gave history of recurrence of such condition. Her first pregnancy was a twin pregnancy, conceived by natural methods, where one of the twins was a male baby who also had achondroplasia and died 2 hours after delivery. The other twin is a girl and the child has delayed developmental milestones. Her second pregnancy was uneventful. The present fetus under study is from her third pregnancy. Her marriage is of second degree consanguineous type. The age of her husband is 36 years old. Germinal mosaicism has been attributed for the causation of recurrent achondroplasia in children, whose parents are normal. 80% of a chondroplasia is due to a new mutation. Only 20% of achondroplasia is inherited. Increased paternal age is a risk factor for new mutations to occur. The other investigations of the case and the genetic analysis are described further in the article.
ABSTRACT
Background and Aims: The Sciatic nerve is the widest nerve of the body, consists of two components namely tibial and common peroneal components, derived from the lumbosacral plexus from the ventral rami of L4 to S3 spinal nerves. The Sciatic nerve usually enters the gluteal region under the piriformis muscle. The purpose of this study is to identify the variations in the course and branching pattern of the sciatic nerve and its relation to the piriformis muscle which may lead to various clinical manifestations like non-discogenic sciatica. Materials and Methods: 50 gluteal regions and posterior compartment of thigh from 25 formalin fixed adult cadavers are used for this study, of which one is a female cadaver. Gluteal regions and the posterior aspect of thigh on both sides are dissected to expose the sciatic nerve. Variations in the sciatic nerve and their relationship to piriformis muscle are observed. Results: 41 gluteal regions and posterior compartments of thigh (82%) showed normal anatomy of sciatic nerve and also piriformis muscle. 9 regions (18%) showed variations in the sciatic nerve, of which 5 regions (10%) showed variation of sciatic nerve in relation to piriformis muscle. Other details are explained further in the article. Conclusion: A proper knowledge about the variations of sciatic nerve, its relation to piriformis muscle is must for medical professionals during posterior hip surgeries, sciatic nerve decompression, total hip replacement, sciatic nerve injury during deep intramuscular gluteal injections, failed sciatic nerve block during anaesthetic procedures etc.