In patients with Chiari malformation type 1 (CMI), epileptic seizures are occasionally reported both in symptomatic patients candidate to surgery and in patients without symptoms of tonsillar displacement in whom CM1 is often an incidental finding in the diagnostic work up for idiopathic epilepsies. In both groups of patients, the course of epilepsy is almost invariably favorable, with a few seizures easily controlled by treatment. In a subset of CM1 patients, epilepsy occurs in the context of neurodevelopmental disorders that also include mental retardation, autism and somatic dysmorphisms. Epileptic seizures must be accurately differentiated by potentially harmful paroxysmal events due to compression of the medulla, particularly by the cerebellar fits characterized by drop attacks, abnormal extensor posturing and apnea 1).
Pandey et al. described a series of children with Chiari I malformation who presented with fulminating symptoms of “cerebellar fits” characterized by drop attacks with or without deterioration of consciousness, opisthotonic posturing, and varying degrees of respiratory compromise.
A retrospective analysis was undertaken of the medical records of 47 consecutive patients undergoing surgery for symptomatic Chiari I malformations at Rainbow Babies and Children's Hospital. Thirteen (28%) of the 47 patients presented with complaints consistent with cerebellar fits. Before the correct diagnosis was made, nine (69%) of the 13 children had previously undergone evaluation with electroencephalography and/or electrocardicography and Holter monitoring because of suspected cortical epilepsy or cardiogenic syncope. In each of the 13 children magnetic resonance imaging demonstrated pegged cerebellar tonsils herniated below the foramen magnum. A deep indentation or blanched discoloration of the cerebellar tonsils was noted in five (38%) of these 13 patients at the time of surgery. Of patients with symptomatic Chiari I malformations, the mean degree of tonsillar herniation was significantly less for those in whom cerebellar fits occurred than those in whom they were absent (8.8 mm and 13.9 mm, respectively; p = 0.007). In only one of the patients with cerebellar fits was a syrinx present, and this was a small focal lower thoracic collection. Spells resolved after surgery in all patients who presented with cerebellar fits.
Cerebellar fits may mimic other disorders such as cardiogenic syncope and epileptic seizures. The correct diagnosis may be delayed or the conditions may be misdiagnosed by those who fail to consider Chiari I malformation as a cause of drop attacks, abnormal extensor posturing, and apneic spells in children. The response to decompressive surgery in these patients is gratifying 2).
4 children with epilepsy (2M, 2F; age range 8-15 y) diagnosed with Chiari type I malformation by brain magnetic resonance imaging (MRI), in whom no cortical structural involvement was observed. In these patients an interictal ethylcysteinate-dimer-single-photon emission computed tomographic (ECD-SPECT) study was performed to define more precisely the relationship between Chiari type I malformation and seizures. In these patients the hypoperfusion area correlated with electroencephalographic (EEG) focal abnormalities. These hypoperfusions may represent the functional aspect of a cerebral microdysgenesis; seizures and EEG epileptic anomalies may also be linked to the complex network connection between cortices and cerebellar hemispheres. A cerebellar hypoperfusion was also detected in two of the four examined patients, indicating a functional or structural involvement.
Interictal SPECT scans are helpful for the clarification of seizures in patients with Chiari type I malformation 3).
Seven subjects with Chiari I malformations and seizures (four males, three females; age range 11 years, 7 months to 36 years; mean, 22.28 +/- 7.58 years; median, 21) were identified in four different centers from among a group of 10 patients. Our aim was to analyze clinical and electroencephalographic characteristics of seizures in this etiologically homogeneous group of patients. Most of the seizures were of the complex partial type, and paroxysmal abnormalities were mainly localized over the frontal and temporal regions. The course of the epilepsy was rather benign, with complete control of seizures in four patients and an important reduction in frequency in the remaining three subjects. Other cortical alterations are not usually associated with the typical abnormalities of the posterior fossa in Chiari I malformation; thus, it is possible to hypothesize that cerebral microdysgenesis or, alternatively, a cerebellar dysfunction could underlie epileptogenesis in these patients 4).
Brill et al. reported 11 children with Chiari I malformation who presented with seizures and developmental delay in motor or language function with or without autistic features. To our knowledge, an association between Chiari I malformation and seizures or neurodevelopmental deficits or both has not been previously reported. We believe that Chiari I malformation should not be considered an incidental finding in these patients, but may be a marker for subtle cerebral dysgenesis. Chiari I and II malformations may constitute a complex but continuous spectrum, related to the timing and severity of a shared underlying embryologic mechanism 5).
An 8-year-old girl was admitted during the night in our emergency department for an acute episode of seizures. The patient underwent computed-tomography (CT) brain scan (Toshiba ® Aquilion 64-TSX-101A/HC) and magnetic resonance imaging (MRI) brain scan (Philips® Achieva 1.5T). CT scan showed left frontal calcified nodules and calcified periventricular subependymal nodules. Subsequently, MRI evaluation revealed cortical and subcortical nodules that showed low signal with respect to the white matter on T1-weighted imaging sequences and high signal both in T2-weighted imaging sequences and in fluid-attenuated inversion recovery sequences. We also showed a herniation of cerebellar tonsils through the foramen magnum (Chiari malformation Type I [CMI]) with the associated hydrosyringomyelic cavity. Our report showed a rare association between tuberous sclerosis complex and CMI 6).
A 4-year-old Caucasian female child with febrile seizures, headache, parasomnias, and a delay of speech. The child underwent a magnetic resonance imaging to investigate these neurological signs, disclosing a Chiari malformation type 1. The polysomnography showed a mild-moderate sleep-disordered breathing, increased number of central sleep apneas, and generalized spike waves at sleep onset. Conclusions:
Seizures have been seldom described in CM1 patients. The main reasons for performing MRI in this case were frequent seizures, a delay of speech, and headache, leading to an unexpected diagnosis of CM1. Polysomnography detected a discrete SDB 7).
Giampietro et al. described a female patient with Arnold Chiari type I malformation, atypical Rett syndrome characterized by postnatal onset microcephaly, stereotypic hand movements, ataxia, severe developmental delay, intractable tonic-clonic seizures, and a MECP2 mutation with a unique set of clinical findings. Implementation of a ketogenic diet resulted in decreased seizure activity and an improvement in the patient's degree of social relatedness with her family members.
An early diagnosis of Rett syndrome allows families to maximize utilization of existing treatment modalities and seek appropriate genetic counseling and prenatal diagnoses. This case also provides further evidence for the treatment benefit of ketogenic diets for seizures in patients with Rett syndrome 8).
A child with Chiari I malformation and cutis marmorata telangiectatica congenita and reviews the medical literature regarding Chiari I malformation and other cutaneous disorders. In addition to cutis marmorata telangiectatica congenita and Chiari I malformation, our patient exhibited hemihypertrophy, Tourette's syndrome, scoliosis, obsessive-compulsive disorder, and seizures. Other associated findings seen in patients with Chiari I malformation include basilar invagination, Klippel-Feil syndrome, atlantoaxial assimilation, scoliosis from an underlying syrinx, and hydrocephalus 9).
Last Update 12/12/2019