Ischemia of the basal ganglia as an immediate consequence of minor head trauma in children under 18 months of age is a rare eventuality (< 2% of all ischemic stroke in childhood) [1], it is caused by vasospasm of the lenticulostriate arteries, frequent in childhood, which are disrupted by head injury. Generally, it manifests with nausea, vomiting, hemiparesis and drowsiness, a clinical picture known as JHTS syndrome (Juvenile Head Trauma Syndrome) [2]. We report the case of a 10 month old child who presented an acute ischemic lesion of the left lenticular nucleus, after a minor head trauma. The ensuing facio-brachio-crural hemiparesis improved over time until complete regression of symptoms 45 days later.

To classify the mild head injury in the case described here, we took into account the guidelines of the Mild Traumatic Brain Injury Interdisciplinary Special Interest Group of the American Congress of Rehabilitation Medicine. These state that mild head trauma is a condition in which there is:

1 - loss of consciousness not exceeding 30 minutes;

2 - GCS between 13 and 15 after 30 minutes from the trauma;

3 - post-traumatic amnesia not exceeding 24 hours [6].

In childhood, cerebral infarction due to a mild head trauma is a rare eventuality, with an estimated incidence of about 1,9% [1]. Despite the rarity of the event, in children less than 18 months old the occurrence of this condition causes ischemia of the basal ganglia and, therefore, facio-brachio-crural hemiparesis, which frequently undergoes remission in a period ranging from one week to several months (usually 3 months) [4]. Secondary causes responsible for cerebral ischemic lesions in children below 18 months are attributable to traumatic dissection of the common carotid, internal carotid arteries or of the vessels of circle of Willis, congenital predisposition to rupture of cervical or intracranial arteries, emboligen heart disease and congenital thrombophilia [7, 8]. In this case, before classifying a cerebral infarction in children below 18 months of age as idiopathic, it is imperative to exclude all possible secondary causes.

In cases similar to the one we describe here, it is necessary to exclude a possibility of surgical treatment of the lesions primarily responsible for symptoms such as bleeding, so the first investigation to perform is a CT scan. Because children are more sensitive to radiation, we prefer not to have a CTA study, but CT scan alone does not show hyperacute ischemic lesions. In this case young patients have to be submitted to:

2 - Brain MRI with Gd-DTPA which shows, when there is a cerebral infarction, hypointense image on T1 and hyperintense on T2, FLAIR and DWI corresponding to the ischemic area. 3 - Angio-MRI to rule out any congenital or anatomical abnormalities due to the trauma of the circle of Willis, responsible for ischemia. Although the gold standard for this purpose remains angiography, we think Angio-MRI should be the first study to be performed after CT scan.

4 - echocardiogram to exclude emboligen heart disease and echocolordoppler to exclude a traumatic carotid dissection.

5 - complete blood work-up in suspected congenital thrombophilia.

In the event of an idiopathic ictus cerebri in a child < 18 months of age after a mild head trauma, the aetiology is due to the particular anatomical characteristics of the arteries and of the brain parenchyma at this age, especially the lenticulostriate arteries, terminal branches of ACM responsible for the flow to caudate, putamen, internal capsule and pallidus. These vessels create an acute angle with the middle cerebral artery, which is more acute in childhood than in the adulthood [9, 10]. Other vessels that may be involved are the thalamo-perforating and choroidal arteries. In addition, the lateral perforators make a more acute angle than the medial perforators, which more readily undergo stretching during head trauma. The lateral perforators are shorter in children, encouraging them to stretch. Anatomically, therefore, between the intraparenchymal and the extraparenchymal segment of the lenticulostriate arteries, which are relatively fixed (the first connected to the brain parenchyma and the second to the middle cerebral artery), there is a mobile segment which, if stretched by trauma, results in vasospasm and/or thrombosis, causing ischemia of the tributary territory. Moreover, the sphenoid bone in children is not yet fully developed and does not therefore fully cover the temporal lobes, meaning that the brain has greater mobility than the skull base in case of violent deceleration. This would facilitate stretching of the lenticulostriate arteries by traumatic forces, causing vasospasm and thrombosis [11–13]. Another rare condition which may cause stroke in children is a rare syndrome characterized by diffuse cerebral edema and coma as a result of a mutation of the CACNA1A gene, coding for a structural protein for the calcium channel [14] not present in the case we described. Clearly, the occurrence of a minor head trauma in patients with this syndrome can cause an acute ischemic stroke due to a massive edema. Another pathogenetic theory vive that the friction generated between the lenticulostriate arteries and the brain parenchyma that occurs during the separation of the gray and white matter following a brain trauma in children may cause of vasospasm and thrombosis. This would lead to a shutdown of the lenticulostriate flow causing ischemia in the internal capsule with a subsequent facio-brachio-crural hemiparesis [9]. It has also been shown that certain viral infections, especially varicella zoster [15], can cause secondary vascular disease, thus increaseing susceptibility to develop ment of thrombosis or post-traumatic arterial vasospasm. This parameter was negative in our case because the patient had no clinical history of varicella or herpes.

The clinical history of these lesions is particularly favorable because they are usually small, and also because in a period ranging from several weeks to several months, there is usually a complete remission of facial-brachial-crural hemiparesis, typical of this pathology, despite persistence of the ischemic area on MRI. This is due to the well-known neuronal plasticity of the CNS and in particular of the primary motor cortex [16, 17]. The most effective therapeutic approach thus appears to be the conservative one although a review of the pertinent literature over the last 10 years does not clearly indicate which type of treatment is better. In our experience, and in the light of the different pathologies responsible for this type of injury, administration of osmotic diuretics (such as mannitol 0,25-0,50 g/kg 4-6 times a day), to reduce perilesional edema and oral anticoagulants (such as calciparine 80-100 U/kg), to prevent acute stroke and secondary pathologies (emboligen heart disease, thrombophilia and acute traumatic arterial dissections)[18] represent an optimal treatment option in childhood.

Stroke after a minor head trauma in children under 18 months of age is a very rare condition (< 2% of all ischemic stroke in childhood), and is closely related to the anatomic peculiarities of the brain and skull base in childhood. Young patients should be closely monitored and treated conservatively with osmotic diuretics to reduce perilesional edema and oral anticoagulants to prevent acute stroke. Thanks to neuronal plasticity, deficits generally resolve in a period ranging from 1 week to 3 months. At the same time, however, it is very important to exclude, by means of instrumental and laboratory studies, conditions that could favour the onset of ischemia, including emboligen heart disease, thrombophilia and acute traumatic arterial dissections. Generally, prognosis in these cases is good. In our experience, administration of osmotic diuretics and oral anticoagulant drugs represents an optimal form of treatment.

Written informed consent was obtained from the parents of the patient for publication of this case report and accompanying images.