Pachygyria - Case Studies

Case Studies

Scientists at the Sanjay Gandhi Postgraduate Institute of Medical Sciences in Lucknow, India, discovered a rare situation: four siblings with neuronal migration disorders, which they studied and compared to other known cases in the field highlighting the need for revision of the current lissencephaly classification scheme. No family history of mental retardation was reported and all four siblings were born to non-consanguineous parents. The first child had developmental delays and two non-recurrent tonic convulsions as an infant. An MRI performed at age five showed generalized pachygyria with only a few broad gyri in the frontal and temporal lobes. The second child also had developmental delays and mild retardation, but more infantile seizures. Her MRI revealed pachygyria of the frontal and temporal lobes. The third and fourth childs (one female and one male) did not have imaging performed but showed developmental similarities to their siblings. The authors hypothesize that autosomal recessive pattern of inheritance is the cause because all four children of different sexes have similar neuronal migration abnormalities and are from the same non-afflicted parents. After they thoroughly reviewed other studies the authors suggested a new classification involving frontotemporal pachygyria with a normal head circumference which can be broken into subgroups based on the involved lobes and neurological features.

A study dedicated to describing congenital fibrosis of extraocular muscles (a complex strabismus syndrome typically occurring in isolation and resulting from dysfunction of all of part of cranial nerves III and IV) in a group of four patients noted one 12 year old male patient with a history of asphyxia, microcephaly and psychomotor retardation whose craniocerebral CT scan revealed symmetrical expansion of the ventricular system with enlargement of the subarachnoid area as well as pachygyria.

Two of 29 patients called to a study involving hippocampal sclerosis, a neuronal loss associated with febrile convulsions, had evidence of pachygyria in their imaging results.

Pachygyria has not previously been reported as associated with non-ketotic hyperglycinaemia but has been recognized as a radiological feature in children with Zellweger syndrome. This study focused on the second child born to non-consanguineous Caucasian parents. At two days old the child became lethargic, hypotonic and difficult to rouse. The child was incubated and ventilated at the hospital once hypoventilation was noticed. A septic screen and a cerebral CT scan were performed and the CT scan results were abnormal, showing poor grey-white differentiation and prominent cerebral spinal fluid spaces. While the child’s head circumference was relatively normal, her anterior fontanelle was notably small. Her small pupils did constrict in response to light. She did not breathe above the ventilator rate and experienced occasional hiccoughs. Doctors were able to produce a flexor withdrawal to pain from the lower limbs. She had occasional myoclonic jerks but no overt seizure activity. The CT scan revealed pachygyria and partial agenesis of the corpus callosum. Thirty-six hours after the child’s death urine analysis was used to give a diagnosis of non-ketotic hyperglycinaemia. Her urine glycine level was grossly elevated and the CSF glycine was at least 100μmol/L. When compared to other studies, agenesis of the corpus callosum was seen in 6 of the 15 patients in literature findings of the same diagnosis. Gyral abnormalities were reported in 6 of the patients but were not described in detail. Biochemical syndromes previously described as associated with pachygyria, polymicrogyria, and heterotopia include glutaric aciduria type II, multiple peroxisomal oxidative deficiency, Zellweger syndrome, and now include non-ketotic hyperglycinaemia.