A 71‐year‐old man presented with a six‐month history of progressive dysarthria, dysphagia, and unspecific dizziness. Clinical examination revealed a 2‐3‐Hz tremor involving palatal, laryngeal, pharyngeal, and facial muscles, as well as gait ataxia (Supporting Video 1).
Seventeen months prior, a dural arteriovenous fistula (DAVF; Cognard type 3) causing edema in the cerebellum and brainstem (Fig. 1B) had been successfully treated. The initial symptoms leading to the diagnosis of the fistula had consisted of severe ataxia (inability to walk), dysarthria (speech nearly incomprehensible), and disorders of the ocular motor system (saccadic pursuit, gaze‐evoked nystagmus) as well as vertigo. These clinical findings had been posture‐dependent and had markedly worsened in an upright position. After successful hybrid treatment of the fistula, all symptoms had significantly improved.
Figure 1.
Time course of brainstem and cerebellar MRI.
Axial FLAIR/T2 MRI is shown at inferior olivary nucleus (ION; upper row) and cerebellar peduncle/internal auditory meatus level (lower row) at five different time points (A) March, 2011; (B) October, 2016; (C) November, 2016; (D) February, 2017; (E) March, 2018. MRI (A) five years prior to and (B) at diagnosis of dural arteriovenous fistula with cerebellar and pontine edema and diffuse enhancement (not shown); (C–E) MRI after treatment shows reduction of the edema and progressive atrophy of the brainstem, cerebellar peduncles, and cerebellum as well as bilateral T2‐hyperintensities in ION. No MR‐diffusion restriction at any time point.
MRI after tremor onset showed bilateral T2‐hyperintensity of the inferior olivary nucleus (ION; Fig. 1E). Moreover, retrospective analysis of multiple MRI before and after DAVF‐treatment demonstrated progressive cerebellar and brainstem atrophy (Fig. 1A‐E). This analysis suggests a secondary degenerative process that may have been caused by venous hypertension and subsequent vasogenic edema as initial injury within the dentato‐rubro‐olivary pathway, formerly referred to as the Guillain–Mollaret triangle.1 Lesions involving this pathway, but sparing the olives, are known to cause denervation and degeneration of the ION and manifest as a tremor of branchial‐derived muscles.2, 3, 4 The underlying hypertrophic olivary degeneration (HOD) develops the most several weeks or months after denervation, which correlates with the delayed onset of the symptoms.2, 4 Moreover, contralateral atrophy of the cerebellar cortex and dentate nucleus may occur in association with HOD.5 This is consistent with the observation of delayed and progressive cerebellar ataxia in some patients with oculopalatal tremor in particular after larger acute brainstem lesions.2, 4
In conclusion, we present a case of a, most likely, symptomatic palatal tremor (SPT) secondary to a DAVF. The combination of progressive gait ataxia, palatal tremor, and olivary degeneration could also be classified as progressive ataxia and palatal tremor (PAPT) syndrome, which is considered to be a subtype of SPT.2, 6 However, while SPT occurs secondary to an identifiable monophasic structural lesion of the brainstem or cerebellum, PAPT is a sporadic or familial disorder of a yet undetermined, presumed degenerative, etiology with progressive cerebellar atrophy, and in most cases HOD.2, 6 Recently, PAPT has been referred to as a novel tauopathy.7 The rare cases of palatal tremor in combination with tardive progressive ataxia after rather large brainstem lesions4 could be equally classified as sporadic PAPT syndromes with identifiable structural lesion as a specific subtype of SPT. This classification might also be applicable in the case presented here. We hypothesize that the extended venous stasis due to the DAVF led to a bilateral injury of the projections of the dentato‐rubro‐olivary pathway and subsequently to bilateral olivary degeneration with cerebellar atrophy.
Finally, it is important to note that SPT and PAPT have to be distinguished from essential palatal tremor for which there is no evidence for structural lesions and HOD.2
Author Roles
(1) Research Project: A. Conception, B. Organization, C. Execution; (2) Statistical Analysis: A. Design, B. Execution, C. Review and Critique; (3) Manuscript Preparation: A. Writing of the First Draft, B. Review and Critique.
K.P.: 1A, 1B, 1C, 3A
J.G.: 1C, 3B
S.W.: 1B, 1C
J.S.: 3B
H.R.: 3B
A.H.: 1A, 3B
Disclosures
Ethical Compliance Statement: The authors confirm that the approval of an institutional review board was not required for this work. Fully informed consent for publication was obtained from the participant. We confirm that we have read the Journal's position on issues involved in ethical publication and affirm that this work is consistent with those guidelines
Funding Sources and Conflict of Interest: The authors report no sources of funding and no conflicts of interest relevant to this work.
Financial Disclosures for the previous 12 months: K.P. was supported by the Else Kröner‐Forschungskolleg Dresden and A.H. by the Hermann und Lilly Schilling‐Stiftung für Medizinische Forschung im Stifterverband. The authors report no conflicts of interest.
Supporting information
Supporting Video 1. Secondary palatal and laryngeal tremor
Transoral fiberoptic endoscopy shows 2‐3‐Hz palatal tremor, which can also be observed from the transnasal perspective in the axial plane. Laryngoscopy reveals pharyngeal and laryngeal involvement. Facial muscles are also affected. Further clinical examination reveals gait ataxia.
Acknowledgments
The authors thank the patient for participating in this study and for giving consent for publication and Dr. Theresa Reetz, Department of Otorhinolaryngology, University Hospital Dresden, Germany for performing fiberoptic endoscopy.
Relevant disclosures and conflicts of interest are listed at the end of this article.
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Supplementary Materials
Supporting Video 1. Secondary palatal and laryngeal tremor
Transoral fiberoptic endoscopy shows 2‐3‐Hz palatal tremor, which can also be observed from the transnasal perspective in the axial plane. Laryngoscopy reveals pharyngeal and laryngeal involvement. Facial muscles are also affected. Further clinical examination reveals gait ataxia.