Blepharoclonus and Arnold-Chiari malformation

Blepharoclonus in Parkinsonism

Background and Objectives

In clinical practice, we have observed that patients with Parkinson disease (PD) often have blepharoclonus, but its prevalence is not well described in the literature. Understanding the relative frequencies of blepharoclonus in PD and atypical parkinsonian syndromes may shed light on the diagnostic utility of this clinical sign. We aimed to assess (1) the frequency of blepharoclonus in patients with PD in a single-center cohort; (2) the association of blepharoclonus with disease stage, tremor severity, and non-motor symptoms; and (3) the frequency of blepharoclonus in synucleinopathy vs non-synucleinopathy-associated parkinsonism.

Methods

We prospectively enrolled 85 patients, 75 with PD and 10 with atypical parkinsonism. Blepharoclonus was considered present if eyelid fluttering was sustained for >5 seconds after gentle eye closure. For each patient, demographics were collected, and we completed selected questions from the MDS-UPDRS (Unified Parkinson's Disease Rating Scale) part 2, REM Sleep Behavior Disorder Questionnaire, and MDS-UPDRS part 3 tremor assessments and recorded the presence/absence of dyskinesia.

Results

63 of 75 patients with PD (84%) had blepharoclonus. Among the 10 patients with atypical parkinsonism, 5 had synucleinopathy syndromes. Blepharoclonus was present in 3 of 5 patients with synucleinopathy and 0 of 5 patients with non-synucleinopathy-associated parkinsonian syndromes.

Discussion

Blepharoclonus is prevalent in our PD cohort, suggesting possible utility as a clinical marker for PD. The absence of blepharoclonus in a patient with parkinsonism may suggest a non-synucleinopathy (e.g., tauopathy). Analysis of a larger cohort of both PD and atypical parkinsonism would be needed to establish whether blepharoclonus distinguishes PD from atypical parkinsonism, or synucleinopathy from non-synucleinopathy.

The Role of Neurophysiology in Managing Patients with Chiari Malformations

Chiari malformation type 1 (CM1) includes various congenital anomalies that share ectopia of the cerebellar tonsils lower than the foramen magnum, in some cases associated with syringomyelia or hydrocephalus. CM1 can cause dysfunction of the brainstem, spinal cord, and cranial nerves. This functional alteration of the nervous system can be detected by various modalities of neurophysiological tests, such as brainstem auditory evoked potentials, somatosensory evoked potentials, motor evoked potentials, electromyography and nerve conduction studies of the cranial nerves and spinal roots, as well as brainstem reflexes. The main goal of this study is to review the findings of multimodal neurophysiological examinations in published studies of patients with CM1 and their indication in the diagnosis, treatment, and follow-up of these patients, as well as their utility in intraoperative monitoring.

Parent-Reported Executive Dysfunction in Children and Adolescents with Chiari Malformation Type 1

BACKGROUND

Children with Chiari malformation type 1 (CM1) have increasingly presented to neurosurgery clinics. Limited research relating to the cognitive dysfunction experienced by this population has been completed. In adults, inhibition problems and executive dysfunction have been documented.

METHODS

Seventy-seven parental reports of children with CM1 were included in the study. Parents completed questions on a scale rating daily executive functioning as well as reporting on common neurological symptoms.

RESULTS

The sample consisted of 41 males and 36 females with a mean age of 133.57 ± 42.18 months. Thirty-eight subjects had had decompression surgery. The most common neurological symptoms included: headache (69%), a history of pain (31%) and gait disturbance (20%). One third of the sample demonstrated overall executive functioning impairment, with working memory elevations being most prevalent (44%). Depression, gender, age and decompression surgery were not related to executive dysfunction.

CONCLUSIONS

The parental report of executive dysfunction in children with CM1 was higher than the standardized healthy sample. Metacognitive problems, especially working memory and initiation problems were most prevalent. A quick parental rating scale identifying children with executive dysfunction may be beneficial for neurosurgeons and assist with referrals for a more comprehensive neuropsychological assessment.

Stratified whole genome linkage analysis of Chiari type I malformation implicates known Klippel-Feil syndrome genes as putative disease candidates

Chiari Type I Malformation (CMI) is characterized by displacement of the cerebellar tonsils below the base of the skull, resulting in significant neurologic morbidity. Although multiple lines of evidence support a genetic contribution to disease, no genes have been identified. We therefore conducted the largest whole genome linkage screen to date using 367 individuals from 66 families with at least two individuals presenting with nonsyndromic CMI with or without syringomyelia. Initial findings across all 66 families showed minimal evidence for linkage due to suspected genetic heterogeneity. In order to improve power to localize susceptibility genes, stratified linkage analyses were performed using clinical criteria to differentiate families based on etiologic factors. Families were stratified on the presence or absence of clinical features associated with connective tissue disorders (CTDs) since CMI and CTDs frequently co-occur and it has been proposed that CMI patients with CTDs represent a distinct class of patients with a different underlying disease mechanism. Stratified linkage analyses resulted in a marked increase in evidence of linkage to multiple genomic regions consistent with reduced genetic heterogeneity. Of particular interest were two regions (Chr8, Max LOD = 3.04; Chr12, Max LOD = 2.09) identified within the subset of "CTD-negative" families, both of which harbor growth differentiation factors (GDF6, GDF3) implicated in the development of Klippel-Feil syndrome (KFS). Interestingly, roughly 3-5% of CMI patients are diagnosed with KFS. In order to investigate the possibility that CMI and KFS are allelic, GDF3 and GDF6 were sequenced leading to the identification of a previously known KFS missense mutation and potential regulatory variants in GDF6. This study has demonstrated the value of reducing genetic heterogeneity by clinical stratification implicating several convincing biological candidates and further supporting the hypothesis that multiple, distinct mechanisms are responsible for CMI.

Evaluation and management of the Chiari malformation type 1 for the primary care pediatrician

Diagnosis and treatment of CMI is undergoing reexamination that includes redefinition of the anatomic Chiari malformation and refinement and redefinition of the clinical syndrome. Children with SMI present with head pain of some kind, a neurologic deficit, or with signs of spinal cord dysfunction from syrinx. Some will present with no clinical syndrome at all. Presence of anatomic Chiari malformation or compelling clinical Chiari syndrome should lead to evaluation by a neurologist or neurosurgeon experienced with the syndromes and their treatment. Treatment options are varied but usually result in resolution of symptoms. When symptoms persist after surgery, management is complex and not uniformly successful, even in the most experienced hands.

Eyelid movements in health and disease. The supranuclear impairment of the palpebral motility

The eyelid movements are mediated mainly by the orbicularis oculi (OO) and the levator palpebrae superioris (LPS) muscles. Dissociated upper lid functions exhibit different counterbalanced action of these muscles, and in blinking they show a strictly reciprocal innervation. The disturbance of this close LPS-OO relationship likely leads to many of the central lid movement disorders. Three groups of supranuclear motor impairment of lid movements are considered: the disorders of the lid-eye movements' coordination, the disturbances of blinking and lid "postural" maintenance, and the alteration of voluntary lid movements. Nuclei of the posterior commissure control the inhibitory modulation of LPS motor-neuronal activity and they are involved in the lid-eye coordination disorders such as lid retraction, which is observed in the Parinaud's syndrome and also in parkinsonism and progressive supranuclear palsy. Spontaneous (SB) and reflex blinking consist of two components: the inhibition of the basal tonic LPS activity, which keeps the eyes open, and the concurrent activation of the OO muscles. LPS inhibition precedes and outlasts the OO activation. This normal configuration is impaired in parkinsonism and blepharospasm (BSP). SB shows a highly interindividual rate variation (among 10-20 per minute in adults) and abnormal blink rates occur in neurological diseases related to dopaminergic transmission impairments. Lid postural abnormalities include involuntary eyelid closure, which is usually associated with inability to open the eyes. Two major disorders share these two aspects: BSP and blepharocolysis (BCO). BSP consists of an involuntary overactivity of the OO, with LPS co-contraction activity, and is expressed as frequent and prolonged blinks, clonic bursts, prolonged tonic contraction or a blend of all of them. BCO (commonly named "so-called lid opening apraxia") is an overinhibition of the LPS with no evidence of ongoing OO activity. BSP and BCO occur in many instances of idiopathic dystonias and basal ganglia diseases and, less frequently, in rostral brainstem lesions. Both may coincide in the same patient. Voluntary lid movement disorders comprise the impairment of Bell's phenomenon, the voluntary eyelid closure palsy and the so-called cerebral ptosis, all related to lesions of frontal cortical areas and/or the corticospinal system.

Blepharoclonus in multiple sclerosis

OBJECTIVE

Keane described 2 patients with gaze-evoked blepharoclonus (BLC), a form of reflex BLC, and multiple sclerosis (MS). A search for common areas of demyelination and focal axonal atrophy (T1 black holes) of the central nervous system (CNS) in 11 patients with MS exhibiting eyelid closure BLC was conducted employing magnetic resonance imaging (MRI). Finding lesions in common CNS locations on these patients can help to elucidate the pathogenesis of this restricted movement disorder.

MATERIALS AND METHODS

Eleven adult patients with relapsing-remitting, primary or secondary progressive MS were studied. MRI views were completed employing a 1.5-tesla scanner. Contrast Axial T1 imaging was obtained in 9 patients.

RESULTS

TL blackholes were not identified. Ten patients had multiple, scattered periventricular (PV) areas of demyelination. Four patients exhibited brainstem lesions of diverse but inconsistent locations including midbrain, cerebellar peduncle, pons and medulla. In 2 of the patients the brainstem lesions were transient but BLC persisted after the lesions regressed.

CONCLUSION

No common areas of CNS demyelination or focal axonal atrophy were identified on these patients with MS and BLC. The pathogenesis and clinical significance of BLC in MS remains to be elucidated.