An autopsy case of corticobasal degeneration with inferior olivary hypertrophy

We report autopsy results of a female patient who was confirmed pathologically as having corticobasal degeneration (CBD). This patient presented with progressive gait disturbance at the age of 66 years, and subsequently showed parkinsonism with a right-sided predominance and dementia. She was clinically diagnosed as having possible corticobasal syndrome without palatal myoclonus throughout the disease course. An autopsy at 72 years of age revealed that neuronal loss with gliosis was severe in the substantia nigra and the portion from hippocampal cornu ammonis (CA1) region to the parahippocampal gyrus, and mild-to-moderate in the basal ganglia, thalamus, red nucleus, dentate nucleus, and cerebral cortices, predominantly in the frontal lobe. Myelin pallor was observed in the pyramidal tract of the brainstem and central tegmental tract. Neurodegenerative or axonal degenerative findings were observed predominantly on the left side, except for the dentate nucleus, which was more affected on the right side. The inferior olivary nucleus exhibited hypertrophic degeneration predominantly on the left side. The topography of neurodegeneration was likely to correspond to the dentate nucleus and inferior olivary nucleus. Phosphorylated tau-immunoreactive pretangles, neurofibrillary tangles, coiled bodies, and threads were diffusely observed in the whole brain. The distribution of tau deposits was prominent in the deeper affected lesions of the dentate nucleus and inferior olivary nucleus. Inferior olivary hypertrophy is unusual in patients with CBD. It is highly possible that the neurodegeneration of the inferior olivary nucleus followed that of the dentate nucleus in our patient. Moreover, these results indicate not only the severity of neurodegenerative changes, but also that of tau deposition that could be related to the topography of the projections of the dentato-olivary pathway. Tau propagation and subsequent neurodegeneration along the fiber connections may have occurred. Our results support the possibility that progression of CBD lesions can be mediated by tau propagation.

Clinical and radiological characterization of novel FIG4-related combined system disease with neuropathy

Variants in the FIG4 gene, which encodes a phosphatidylinositol-3,5-bisphosphatase lead to obstruction of endocytic trafficking, causing accumulation of enlarged vesicles in murine peripheral neurons and fibroblasts. Bi-allelic pathogenic variants in FIG4 are associated with neurological disorders including Charcot-Marie-Tooth disease type-4J (CMT4J) and Yunis-Varón syndrome (YVS). We present four probands from three unrelated families, all homozygous for a recurrent FIG4 missense variant c.506A>C p.(Tyr169Ser), with a novel phenotype involving features of both CMT4J and YVS. Three presented with infant-onset dystonia and one with hypotonia. All have depressed lower limb reflexes and distal muscle weakness, two have nerve conduction studies (NCS) consistent with severe sensorimotor demyelinating peripheral neuropathy and one had NCS showing patchy intermediate/mildly reduced motor conduction velocities. All have cognitive impairment and three have swallowing difficulties. MRI showed cerebellar atrophy and bilateral T2 hyperintense medullary swellings in all patients. These children represent a novel clinicoradiological phenotype and suggest that phenotypes associated with FIG4 missense variants do not neatly fall into previously described diagnoses but can present with variable features. Analysis of this gene should be considered in patients with central and peripheral neurological signs and medullary radiological changes, providing earlier diagnosis and informing reproductive choices.

Longitudinal Quantification of Eye-Movement Impairments after Pontine Hemorrhage

INTRODUCTION

We report a case of hypertrophic olivary degeneration due to pontine hemorrhage. A 59-year-old male with untreated hypertension suffered a primary pontine hemorrhage, which caused horizontal eye-movement limitation. Progressive neurological deterioration with involuntary eye and palatal movements began months after hemorrhage. This was accompanied by magnetic resonance imaging evidence of hypertrophic olivary degeneration at 4.5 months.

BACKGROUND

Primary pontine hemorrhage often leads to impairment of eye movements and diplopia. Hypertrophic olivary degeneration can also emerge months after hemorrhage, producing involuntary pendular eye movements. Neither the natural history of voluntary eye movements nor the emergence of involuntary eye movements after pontine hemorrhage has been previously quantified.

METHODS

We used an optokinetic task that enabled measurement of eye movements. It provided real-time feedback on the ability to track continuously and saccade quickly in a pursuit task. The feedback motivated the patient to use the system repeatedly in his home. From 3 months after hemorrhage, the patient used the system for 9 months, allowing us to quantify changes in his eye movements.

RESULTS

Horizontal gaze impairments were manifest in our task as limitation in horizontal range of motion, as well as delay in initiation of the right eye's movement during left-to-right pursuit. Improvement in these impairments was measured over the course of months 3-7 post hemorrhage. In addition, the emergence of vertical pendular nystagmus was identified in the subject at 4 months. Analysis of the eye-movement records revealed presymptomatic oscillatory eye movements whose amplitude had grown steadily over the course of 3 weeks, prior to a sharp increase in amplitude that coincided with the patient's first report of oscillopsia. Horizontal pendular nystagmus emerged 7.4 months after the hemorrhage, primarily in the left eye.

CONCLUSION

An eye-tracking system deployed in a patient's home enabled prospective longitudinal quantification of the natural history and improvement in voluntary eye-movement impairments after pontine hemorrhage. It also characterized prospectively for the first time, the emergence of involuntary eye movements resulting from the rare complication of hypertrophic olivary degeneration. Results suggest that brief weekly measurements with an eye-tracker may allow early detection of this complication.

Bilateral Hypertrophic Olivary Degeneration and Holmes Tremor without Palatal Tremor: An Unusual Association

BACKGROUND

Lesions in the Guillain-Mollaret triangle or dentate-rubro-olivary pathway may lead to hypertrophic olivary degeneration (HOD), a secondary trans-synaptic degeneration of the inferior olivary nucleus. HOD is usually associated with palatal tremor and rarely with Holmes tremor. Bilateral HOD is a very unusual condition and very few cases are reported.

CASE REPORT

We report here two cases of bilateral HOD after two different vascular lesions located at the decussation of superior cerebellar peduncles, thus impairing both central tegmental tracts and interrupting bilaterally the dentate-rubral-olivary pathway. Interestingly, both developed bilateral Holmes tremor but not palatal tremor.

DISCUSSION

Lesions in some of the components in the Guillain-Mollaret triangle may develop Holmes tremor with HOD and without palatal tremor. Magnetic resonance imaging is an invaluable tool in these cases. Better understanding of the pathways in this loop is needed.