|Ahead of print
Rhombencephalo synapsis: A rare cerebellar anomaly with Gómez–López-Hernández syndrome
Leema Pauline Cornelius, Neeraj Elango, Venkateswaran Kuttava Jeyaram
Department of Paediatric Neurology, Institute of Child Health & Hospital for Children, Madras Medical College, Chennai, Tamil Nadu, India
|Date of Submission||07-Nov-2021|
|Date of Acceptance||26-Dec-2021|
|Date of Web Publication||30-Jan-2023|
Leema Pauline Cornelius,
Department of Paediatric Neurology, Institute of Child Health & Hospital for Children, Bhanumati, Rina Mandal Rd, Egmore, Chennai 600008, Tamil Nadu
Source of Support: None, Conflict of Interest: None
Keywords: Alopecia, corneal anesthesia, rhombencephalo synapsis
| Introduction|| |
Rhombencephalo synapsis (RES) is an extremely rare cerebellar malformation, characterized by vermian agenesis or hypogenesis and fusion of cerebellar hemispheres. It can occur as an isolated anomaly or associated with other cerebral and/or extracranial anomalies. The syndromic associations include Gómez–López-Hernández syndrome (GLHS) and VACTERL association. Hereby, we report a child with RES as a part of GLHS.
| Case Vignette|| |
A 4-month-old male child was referred to us for facial dysmorphism. He was the firstborn of nonconsanguineous parents, delivered by cesarean section for breech presentation, and was preterm admitted in newborn period for respiratory distress. There were no H/O neonatal seizures. He has not attained social smile and had partial head control. The antenatal period was uneventful. There was no H/O abnormal odor of urine or family history of developmental delay, dysmorphism, or mental subnormality.
Examination revealed a conscious child with turricephaly, wide-open anterior fontanel, low-set ears, high-arched palate, and inverted V-shaped upper lip. There were no nystagmus, cataract, squint, or umbilical hernia. He had bilateral temporal and parietal alopecia in the scalp. External genitalia and spine were normal. He had bilateral corneal opacity and was not following the light. There was spasticity in both lower limbs with brisk deep tendon reflexes.
Investigations showed normal thyroid profile, renal, and liver function tests. The skeletal survey did not show any abnormality. Urine screening tests were negative. Ophthalmic examination revealed bilateral corneal opacity with multiple abrasions due to bilateral corneal hypoesthesia. Fundi were normal. Echocardiogram was normal. Ultrasonogram abdomen revealed the absence of kidney on the left side.
Magnetic resonance imaging of the brain showed fused cerebellar hemispheres in the midline with absent vermis, small brainstem and posterior fossa, diamond-shaped IV ventricle, and mild dilatation of left lateral ventricle [Figure 1].
|Figure 1: (A and B) MRI brain axial view FLAIR sequence showing fused cerebellar hemispheres, absent vermis, and diamond-shaped IV ventricle. (C) Coronal T1W image showing transversely oriented single lobed cerebellum|
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A diagnosis of GLHS was made based on the imaging feature of RES and the presence of corneal anesthesia and bitemporo-parietal alopecia.
| Discussion|| |
RES, a rare hindbrain malformation manifesting as a fusion of the cerebellar hemispheres, the dentate nuclei, and the superior cerebellar peduncles, is associated with agenesis/hypogenesis of the vermis. It can occur as an isolated anomaly or as a part of wider cerebral malformations such as aqueductal stenosis, agenesis of the corpus callosum, absent septum pellucidum, olfactory bulbs, posterior lobe of the pituitary, hypoplasia of anterior visual pathway, and holoprosencephaly. Extracranial abnormalities involve the musculoskeletal, urinary, cardiac, and respiratory systems.
The most common syndromic association of RES is GLHS syndrome (Cerebello Trigeminal Dermal Dysplasia), first documented by Gómez and reported by López-Hernández. It is a rare neurocutaneous syndrome that includes a triad of RES, trigeminal anesthesia leading to corneal opacity, and scalp alopecia. Other craniofacial features of this syndrome are low-set ears, brachyturricephaly, mid-face retrusion, widely spaced eyes, strabismus, low-set, and posteriorly angulated ears. Although approximately 74 cases have been reported worldwide, only two cases are from our subcontinent to the best of our knowledge., Neurological manifestations include developmental delay, mental retardation, hypotonia, head shaking, ataxia, stereotypies, and behavioral problems.
Different degrees of trigeminal anesthesia may lead to recurrent corneal and facial scarring. However, trigeminal anesthesia is seen in just over half of reported patients only. In the absence of trigeminal anesthesia, one of two major craniofacial findings (brachycephaly and/or turricephaly or midface retrusion) is sufficient to make a diagnosis of GLHS. Our patient had all three features of GLHS––RES, alopecia, and trigeminal anesthesia.
Unusual stereotypic movements of the head in the “figure of eight” pattern have been described in many patients with GLHS. Parietal or parieto-occipital alopecia is often bilateral and may be hidden by surrounding scalp hair. The cognitive involvement may range from moderate-to-severe impairment to normal cognitive function.
Embryologically, an insult to the embryo at 28–44 days of gestation can cause the developmental arrest of part of the ectoderm from which the alar plate of the rhombencephalon, overlying epidermis, trigeminal nucleus, and trigeminal placodes arise, which can give rise to a constellation of findings of GLHS.
Most cases of GLHS occur sporadically, except in a few where consanguinity has been reported. The genetic basis of this syndrome is not known and no specific gene mutations or chromosomal abnormalities have been identified so far.
Treatment is symptomatic care which includes physiotherapy, occupational therapy, and ocular protection against self-induced corneal trauma leading to corneal ulcer, opacification, and phthisis bulbi in extreme cases. The prognosis depends on the motor and intellectual handicap, corneal–facial anesthesia, and visual problems. Parents should be advised regarding the vulnerability of developing corneal lesions and the importance of regular follow-up and prompt treatment to prevent vision-threatening abnormalities.
To conclude, RES is a rare cerebellar anomaly with absent vermis and fusion of cerebellar hemispheres resulting in transversely oriented single lobed cerebellum. Whenever RES is diagnosed by neuroimaging, one should look for clinical signs of GLHS such as alopecia and trigeminal anesthesia.
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Conflicts of interest
There are no conflicts of interest.
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