Hemimyelomeningocele: Varieties of Diagnosis and Clinic

Objective The term hemimyelomeningocele refers to a rare condition of spinal dysraphism in which open neural placode is localized in one hemicord of a split cord malformation of type I. This entity requires attention due to lack of overt clinical evidence and neuroradiological investigation since the open neural tube defect of the newborn is generally repaired as an emergency.

Method Between 1989 and 2013, 800 newborns and infants with an open neural tube defect were operated on at the Division of Pediatric Neurosurgery at Marmara University Medical Center and Acibadem University, Department of Neurosurgery. A total of 168 patients (21%) presented an associated split cord malformation and within this group 32 cases (4%) were diagnosed as hemimyelomeningocele. The diagnosis of hemimyelomeningocele has been made either during preoperative physical examination or incidentally during operation. In 28 cases, the placode had a paramedian localization, with hypertrichosis in 16 cases. Scoliosis was present in 11 cases, with an additional foot deformity in 6 of them. In cases with neurological deficit, the deficit was typically asymmetrical. Five cases have been noted to have a normal neurological examination. Sensorimotor function was preserved on the side of the closed hemicord. In surgery, the neural tube is reconstructed, the septum removed, and a duraplasty was performed. There were no surgical morbidity and mortality. Detailed postoperative investigation with magnetic resonance imaging revealed the split cord malformation with two hemicords. Within the first month after surgery, urine analysis and culture, urinary system ultrasound, and voiding cystourethrogram were also performed.

Results Only two patients presented with neurogenic bladder in the long-term follow-up period. The mean follow-up period was 5 years. Nine children needed a shunt during early infancy. Twelve children were classified as grade 2, whereas 20 as grade 3 according to the Oi and Matsumato's Spina Bifida Neurological Scale (SBNS).

Conclusions Hemimyelomeningocele is a rare subgroup of spina bifida, which has significantly better prognosis compared with other types of spina bifida. Preoperative diagnosis of both hemicords is crucial to preserve the intact hemicord during surgery.

Keywords hemimyelomeningocele; hemicord; deformities