Long-standing myoclonic hand tremor as an isolated symptom of hypertrophic olivary degeneration.

Hypertrophic olivary degeneration (HOD) is a rare condition caused by lesions of the dentato-rubro-olivary pathway, usually bilateral. We presented a case of a 64-year old male with HOD caused by a unilateral, posterior pontine cavernoma. The patient has not developed the typical palate myoclonus until recently. Isolated hand myoclonus with coexisting asterixis was present for years. This case shows unique HOD symptomatology and emphasizes the important role of MRI in the differential diagnosis of monomelic myoclonus.

Hypertrophic olivary degeneration associated with bilateral vocal cord adductor dystonia.

BACKGROUND: Hypertrophic olivary degeneration (HOD) is a rare condition caused by lesions within the dentato-rubro-olivary pathway, resulting in ocular nystagmus and palatal myoclonus (oculopalatal tremor) but not usually dystonia. Dystonia is an uncommon association, and we present the first reported association of hypertrophic olivary degeneration with bilateral vocal cord dystonia. CASE PRESENTATION: A 33 year old male presented initially with acute hydrocephalus on the background of previous ventriculoperitoneal (VP) shunting for previously treated medulloblastoma. After revision of the VP shunt, the patient developed progressive hiccups and stridor leading to respiratory failure requiring intubation. Ocular pendular nystagmus and palatal myoclonus at 3 Hz was observed. Flexible nasendoscopy (FNE) demonstrated bilateral tonic adduction of the vocal folds with 3 Hz coarse supraglottic, pharyngeal and palatal rhythmic myoclonus. MRI imaging demonstrated T2 hyperintensity within the bilateral inferior olivary nuclei consistent with stage 3 radiological HOD. CONCLUSIONS: Dystonia is a rarely reported phenomenon in HOD but is not unexpected with the inferior olivary nucleus implicated in dystonic disorders. We report the association of HOD with bilateral vocal cord adductor dystonia, a potentially life threatening condition.

Hypertrophic Olivary Degeneration Postoperatively Following Pilocytic Astrocytoma Resection.

A 25-year-old male presented with headaches 3 weeks after a car accident. His magnetic resonance imaging images showed a hemorrhagic vermis mass with fourth ventricle effacement. One month later, he underwent suboccipital craniotomy for removal of a pilocytic astrocytoma. A 3-month postoperative scan demonstrated a new area of medullary hyperintensity in the inferior olive, which was also present 7 months postoperatively consistent with hypertrophic olivary degeneration. This condition is caused by disruption to the dento-rubro-olivary pathway with magnetic resonance imaging enlargement of the inferior olivary nucleus and increased T2 signal. Hypertrophic olivary degeneration should be considered after cerebellar surgery and should not be mistaken for tumor recurrence.

Deep brain stimulation as a palliative treatment for myorhythmia: A case of failure.

BACKGROUND AND PURPOSE: Myorhythmia is a hyperkinetic movement disorder that derives from a disruption of the Guillain-Mollaret triangle, due to an identifiable structural lesion. It is often disabling and with disappointing control under medical treatment. METHODS: Herein, a case of myorhythmia secondary to a vascular insult in the brainstem is reported and an unsuccessful attempt to palliate it with functional neurosurgery. RESULTS: A 67-year-old man displayed a repetitive, rhythmic, slow 2-3 Hz movement, 6 months after suffering a pontomesencephalic hypertensive haematoma. The kinetic phenomenon affected the orbicular and low facial muscles, the neck, the thorax and the upper limbs. Furthermore, he exhibited tremor of the soft palate and pendular nystagmus. On T2-weighted magnetic resonance imaging, hypertrophic degeneration of the inferior olivary complex was seen. He was diagnosed with secondary myorhythmia and multiple pharmacological treatments were tested, but failed. Ultimately, deep brain stimulation with bilateral electrodes placed in the thalamic ventralis intermedius nucleus was offered. Unfortunately, no alleviation of the symptoms was achieved other than mild improvement in involuntary eye movements. CONCLUSIONS: This is the first case to report the use of deep brain stimulation for myorhythmia. Better understanding of the pathophysiology of this condition, and localization of the pacemaker, may allow identification of reliable neurosurgical therapeutic targets.

Bilateral Hypertrophic Olivary Degeneration as a Paraneoplastic Syndrome of a Poorly Differentiated Carcinoma of the Upper Gastrointestinal Tract: A Case Report and Literature Review.

INTRODUCTION: Hypertrophic olivary degeneration (HOD) is a unique form of trans-synaptic neuronal degeneration within the dentato-rubro-olivary pathway which is manifested by the enlargement and hyperintensities of the inferior olivary nucleus in the brain magnetic resonance imaging. CASE REPORT: We report a 53-year-old man admitted to our emergency department with a history of progressive ataxia and vertigo for 6 months before admission. Neurological examination revealed cerebellar dysfunction, and the brain magnetic resonance imaging showed bilateral HOD without an identifiable causative lesion within the brain or abnormal meningeal enhancement. Cerebrospinal fluid analysis showed mild lymphocytic pleocytosis, elevated protein, and negative cytology. Malignancy and paraneoplastic workup exhibited marked elevation of carbohydrate antigen 19-9 level and para-aortic lymphadenopathy. A histologic examination demonstrated the infiltration of lymph nodes by a malignant, poorly differentiated carcinomatous tumor that arises from the upper gastrointestinal tract. Considering the primary site of the tumor and HOD as a paraneoplastic effect of carcinoma, a FOLFIRINOX regimen, intravenous immunoglobulin, and pulse methylprednisolone were started. A follow-up imaging after 3 months depicted a significant resolution of HOD but the neurological status only mildly improved. The patient developed liver and adrenal metastasis over the following 6 months, culminating in his death. CONCLUSION: This study strengthens a relationship between HOD and malignancy as a paraneoplastic syndrome and provides a new incentive for further researches to confirm this association.

Primary intracranial germ cell tumour originating from right brachium Pontis with hypertrophic Olivary degeneration: a case report.

BACKGROUND: Primary right brachium pontis germinoma with hypertrophic olivary degeneration (HOD) is extremely rare. A preoperative diagnosis is challenging due to the absence of characterized clinical and neuroimaging features, and biopsy should be considered. CASE PRESENTATION: A 20-year-old male patient presented with a case of primary intracranial germinoma originating from right brachium pontis with HOD manifesting as ocular myoclonus, nystagmus in both eyes, ataxic gait and incoordination of the limbs. Magnetic resonance imaging (MRI) revealed an irregular patchy lesion with hyperintensity on T2-weighted images (T2WI) and T2 fluid-attenuated inversion recovery (FLAIR) without enhancement by gadolinium (Gd). Furthermore, a focal hyperintense nodule on T2WI in the left inferior olive nucleus (ION) of the medulla oblongata was considered hypertrophic olivary degeneration (HOD) based on the patient's symptoms and neuroimaging findings. Due to suspected demyelinating disease and low-grade glioma (LGG), a biopsy was planned. The pathological diagnosis was germinoma. Subsequently, he received chemoradiation therapy, resulting in the improvement of neurological deficits and the disappearance of the lesion on MRI. CONCLUSION: A case of "Primary right brachium pontis germinoma with HOD" is reported for the first time. A preoperative diagnosis is challenging due to the fact of absence of clinical signs and symptoms and neuroimaging characteristics. However, patients can have favourable prognoses with appropriate evaluation and treatment.

Transient Palatal Tremor and Action Induced Foot and Leg Dystonia due to Hypertrophic Olivary Degeneration: a Case Report.

Hypertrophic olivary degeneration (HOD) is a rare phenomenon that occurs after various insults to the Guillain-mollaret triangle (GMT). HOD is unique because the degeneration of inferior olivary nucleus becomes hypertrophic rather than atrophic. In this study, a 31-year-old woman developed HOD after pontine cavernoma surgery had been performed. The clinical manifestation was involuntary intorsion of right lower extremity during walking, which has not been reported in the literature. The woman also presented with palatal tremor, the most classic symptom of HOD. HOD's imaging trait include olive hypertrophy with increased T2 signal intensity on MRI, which are corresponding to the pathological findings. HOD is a self-limiting disease and excessive treatments are unnecessary.

Hypertrophic Olivary Degeneration and Holmes Tremor: Case Report and Review of the Literature.

BACKGROUND: Hypertrophic olivary degeneration (HOD) is very rare type of degeneration that causes hypertrophy rather than atrophy. The classical presentation of HOD is palatal myoclonus. However, HOD may rarely present with Holmes tremor (HT). HT is unusual symptomatic tremor characterized by combination of rest and intention tremor. It has been reported in small case series, so far. CASE DESCRIPTION: In this study, a man aged 62 years with HOD and HT spreading to the upper and lower extremities after pontine-midbrain hemorrhage due to cavernoma was presented. CONCLUSIONS: Although pontine-midbrain hemorrhage may cause HT in the late period, HOD can be revealed on magnetic resonance imaging. Tract anatomy, especially the Guillain-Mollaret triangle, should be considered to explain the relationship between HT and HOD.

[Hypertrophic olivary degeneration : Cause of new neurological symptoms after stroke]. / Hypertrophe Degeneration der Olive : Ursache neuerlicher neurologischer Symptome nach Schlaganfall.

BACKGROUND: Hypertrophic olivary degeneration (HOD) occurs as a result of a lesion in the anatomical functional loop of the Guillain-Mollaret triangle. Frequent causes are intracerebral hemorrhage and brain infarction. After a latent period of weeks to months after the index event a hyperintensity can initially be observed in magnetic resonance imaging T2/FLAIR-weighting and finally an enlargement of the affected olive. Characteristic symptoms are a rhythmic palatal tremor, a primarily vertical pendular nystagmus as well as Holmes' tremor of the upper limbs. AIM OF THE STUDY: The goal of this study was to illustrate the course of the disease and its clinical presentation in order to provide an improved understanding of the pathophysiology of HOD after stroke. MATERIAL AND METHODS: The neuroradiological database of the Goethe University Hospital was screened for HOD and related keywords (in German). Between 2010 and 2017 a total of 27 cases of HOD were identified, of which 12 patients had suffered a stroke in their medical history. RESULTS: The mean age of the 12 patients was 51.4 years (±13.6 years) and one third of the patients were women. Of the patients eight had an intracerebral hemorrhage, three an ischemic stroke and one had a subarachnoid hemorrhage as the causative event. The lesions were located in the pons (n = 7), cerebellum (n = 4) and pontomesencephalon (n = 1). The median latent period from the causative index event to radiological diagnosis was 24 months (min. 4 months, max. 115 months). The leading symptoms of HOD were palatal tremor (55%), Holmes' tremor (18%), pendular nystagmus (18%) and dysarthria (73%). A logopedic examination with flexible endoscopic evaluation of swallowing (FEES) could determine a palatal tremor in five out of nine cases. The diagnosis of HOD was named in the medical report in only 50% of the cases. CONCLUSION: Analysis of the dataset provided confirmation of the results in the literature that lesions within the Guillain-Mollaret triangle more often lead to HOD. Patients with corresponding symptoms should be closely observed over time with respect to the occurrence of corresponding clinical and imaging leading symptoms. Even though the named clinical symptoms are characteristic for HOD, in many cases the diagnosis is hampered and delayed by imprecise examination and misinterpretation of the symptoms. A logopedic examination using FEES in this collective often provided indicative information. Currently, no reliable data are available on the incidence of HOD after brainstem lesions or on potential preventive and treatment options. Future epidemiological and translational studies could perspectively enable valuable insights to be gained.

New Radiologic Findings of Hypertrophic Olivary Degeneration in 2 Patients with Brainstem Lymphoma.

BACKGROUND: Hypertrophic olivary degeneration (HOD) is a rare neurological condition of trans-synaptic degeneration caused by disruption of the dentatorubro-olivary pathway. We present new radiologic findings of HOD in 2 cases of brainstem lymphoma. CASE DESCRIPTION: A 35-year-old woman (Case 1) and a 69-year-old man (Case 2) presented with remarkably similar clinical courses. The primary lesion was located at the dorsal pons extending to the midbrain. Pathologic diagnosis of diffuse large B-cell lymphoma was obtained after surgical resection. Complete remission of the primary lesion was achieved by treatment with 3 courses of high-dose methotrexate and radiotherapy. Arterial spin-labeling and T2-weighted imagings showed high signal intensity in the inferior olive (IO) at some time after the operation. Slight contrast enhancement in the IO was also found in Case 1. These radiologic findings nearly misled us into a diagnosis of recurrence of lymphoma. Signal intensity in the IO on arterial spin-labeling imaging changed with time. Normalized regional cerebral blood flow (rCBF) in the IO was defined as a percentage of rCBF to the global cerebral blood flow calculated using automated software. Chronologic change in normalized rCBF in the IO revealed a large peak in Case 1, but only a mild increase in Case 2. Neurological findings demonstrated severe oculopalatal tremor in Case 1 and mild palatal tremor in Case 2. CONCLUSIONS: Hyperperfusion and contrast enhancement in the IO were found in 2 patients with HOD. These findings may be confused with recurrence of malignant tumor.

Hypertrophic Olivary Degeneration: Neurosurgical Perspective and Literature Review.

BACKGROUND: Hypertrophic olivary degeneration (HOD) occurs because of posterior fossa or brainstem lesions that disrupt the dentato-rubro-olivary tract, well known as the Guillain-Mollaret triangle. Clinical and radiologic hallmarks of this condition are palatal myoclonus and T2 hyperintensity of the inferior olivary complex on magnetic resonance imaging (MRI), respectively. Because symptomatic HOD can complicate the recovery of patients with posterior fossa or brainstem lesions, the purpose of this study is to evaluate clinical and imaging findings of patients with HOD. METHODS: Sixteen patients (8 female and 8 male) with a mean age of 40.7 years, (range, 5-83 years) years were included in this study based on clinical symptoms and MRI findings. RESULTS: We reviewed the clinical and imaging findings in 16 cases of HOD at our institution. Seven patients (43.7%) had posterior fossa tumors, 6 patients (37.5%) had cavernoma, 2 patients (12.5%) sustained traumatic brain injury, and only 1 patient (6.2%) had cerebellar infarction. Posterior fossa surgery was performed in 13 (81.2%) of these patients. HOD was detected a mean of 7.2 months (range, 0.5-18 months) after surgery or primary neurologic insult. Unilateral HOD was observed in 10 patients (62.5%), while bilateral HOD was observed in only 6 patients (37.5%). Seven patients (43.7%) were asymptomatic for HOD, whereas 5 patients (31.2%) had symptoms attributable to HOD. Two patients died because of primary tumors, although mean follow-up after detection of HOD on MRI was 52.2 months (range, 1-120 months) in the remaining 14 patients. In these cases, no change in clinical symptoms or imaging findings was detected during follow-up. CONCLUSIONS: In this series, posterior fossa tumors and cavernomas were the most common causes of HOD. Although most of the patients with HOD remained asymptomatic, HOD complicated the course of recovery in almost one quarter of the patients included in this study. Neurosurgeons should be aware of HOD, which has characteristic clinical and imaging findings. In addition, HOD can complicate the recovery of patients with disruption to the dentato-rubro-olivary tract.

Bilateral surgical damage of the central tegmental tract resulting in bilateral hypertrophic olivary degeneration: An MRI case report.

Hypertrophic olivary degeneration (HOD) is a rare trans-synaptic neuronal degeneration of the inferior olivary nucleus caused by an injury to the dentato-rubro-olivary connection, also known as Guillain-Mollaret triangle. It leads to hypertrophy of the affected nucleus rather than atrophy and is characterized by hyperintensity on T2-weighted images. Unilateral and bilateral cases are described. We present a case of a 70-year-old patient affected by a tumor inside the fourth ventricle who suffered from diplopia and right seventh cranial nerve palsy. He underwent surgery and developed left seventh cranial nerve palsy. Three months after resection, magnetic resonance imaging revealed the appearance of bilateral HOD. This is the first report of bilateral HOD occurrence after surgical bilateral damage of the rubro-olivary fibers running in central tegmental tracts.

The dentato-rubro-olivary pathway revisited: New MR imaging observations regarding hypertrophic olivary degeneration.

Hypertrophic olivary degeneration (HOD) following a lesion of the dentato-rubro-olivary pathway (DROP) is a well-known imaging finding and has extensively been described in the recent literature. We reviewed our patients with HOD as a result of a lesion of the DROP in order to analyze the disruption of the DROP and the resulting HOD in comparison with the literature. We observed unusual imaging findings in four patients. In two patients it concerned new observations related to the timing and imaging appearances of HOD. HOD became only visible 6 years after a lesion in the red nucleus in one patient and a cystic degeneration of the olivary nucleus was seen 3 years after the HOD in a second patient. In two patients we found HOD that could only be explained by the existence of an afferent feedback loop between the dentate nucleus and the inferior olivary nucleus and by the knowledge that these fibers run through the ipsilateral olivary nucleus before ending in the contralateral olivary nucleus. In one of these patients the lesion was located in the inferior cerebellar peduncle. In the other patient the lesion was located on the midline in the medulla oblongata. The imaging findings in these patients reveal new observations in the stages of imaging appearances in HOD and shed light on the forgotten dentato-olivary afferent feedback loop of the DROP. Clin. Anat. 30:543-549, 2017. © 2017 Wiley Periodicals, Inc.

Palatal and Oromandibular Tremor Secondary to Degenerative Olivary Hypertrophy After Ependymoma Surgery.

Palatal tremor (PT) is a rare movement disorder that involves pharynx, tongue, and other facial muscles. Symptomatic PT is due to lesions on the dentate-rubro-olivary pathways. We present an illustrative case of PT due to degenerative olivary hypertrophy after ependymoma surgery.

Hypertrophic Olivary Degeneration: A Neurosurgical Point of View.

Hypertrophic olivary degeneration (HOD) is a rare form of transsynaptic degeneration characterized by hypertrophy of the inferior olivary nucleus situated in the olivary body, part of the medulla oblongata, representing a major source of input to the cerebellum. HOD typically results from focal lesions interrupting connections from the inferior olive within the dentato-rubro-olivary pathway, a region also known as the triangle of Guillain-Mollaret (TGM) (red nucleus, inferior olivary nucleus, and contralateral dentate nucleus). Clinically, HOD presents classically as palatal tremor and can include dentatorubral tremor and/or ocular myoclonus. The pathologic changes associated with HOD feature radiologic changes with the inferior olivary nucleus appearing larger and increasing its T2-weighted signal intensity on magnetic resonance images. HOD is commonly managed with pharmacotherapy but may require surgical intervention in extreme cases. HOD has been found to develop as a consequence of any injury that disrupts the TGM pathways (e.g., pontine cavernoma).These findings highlight the critical importance of a thorough knowledge of TGM anatomy to avoid secondary HOD. We present a patient who developed HOD secondary to resection of a tectal plate cavernous malformation and review the literature with an emphasis on the current knowledge of this disorder.

Hypertrophic olivary degeneration resulting from posterior fossa masses and their treatments.

PURPOSE: Characterize hypertrophic olivary degeneration (HOD) that develops from posterior fossa masses and their treatments. METHODS: Retrospectively reviewed MR images and clinical data of 10 patients with posterior fossa masses and HOD. RESULTS: Eight patients had cerebellar lesions, and two patients had pontine lesions. Lesions consisted of tumors, demyelination, and nonspecific necrosis. MRI showed T2 hyperintense signal in the inferior olive a median 86 days after the diagnosis of a posterior fossa lesion. HOD presented prior to surgery (n=2), after surgery (n=3), after surgery/radiation therapy (n=4), or without treatment (n=1). CONCLUSIONS: HOD may develop from posterior fossa masses and surgical and/or radiation therapy.

Hypertrophic olivary degeneration secondary to pontine haemorrhage.

We report a 58-year-old man who developed hyptertrophic olivary degeneration (HOD) after haemorrhage of a cavernous malformation in the pons. Lesions of the triangle of Guillain and Mollaret (the dentatorubro-olivary pathway) may lead to HOD, a secondary transsynaptic degeneration of the inferior olivary nucleus. HOD is considered unique because the degenerating olive initially becomes hypertrophic rather than atrophic. The primary lesion causing pathway interruption is often haemorrhage, either due to hypertension, trauma, surgery or, as in our patient, a vascular malformation such as a cavernoma. Ischaemia and demyelination can also occasionally be the inciting events. The classic clinical presentation of HOD is palatal myoclonus, although not all patients with HOD develop this symptom. The imaging features of HOD evolve through characteristic phases. The clue to the diagnosis of HOD is recognition of the distinct imaging stages and identification of a remote primary lesion in the triangle of Guillain and Mollaret. Familiarity with the classic imaging findings of this rare phenomenon is necessary in order to avoid misdiagnosis and prevent unnecessary intervention.

MRI findings of olivary degeneration after surgery for posterior fossa tumours in children: incidence, time course and correlation with tumour grading.

PURPOSE: Olivary degeneration is due to many posterior cranial fossa (PCF) lesions affecting the dentato-rubro-olivary pathway, also known as Guillain-Mollaret triangle. Triangle damage results in hyperexcitation and consequently in hypertrophy of the inferior olivary nucleus (ION). The aim of our study was to evaluate the incidence of magnetic resonance (MR) imaging changes in the ION after surgery in a large cohort of paediatric patients and to determine their correlation with tumour grade. MATERIALS AND METHODS: We retrospectively evaluated 58 patients treated surgically for PCF tumours who underwent MR imaging between 2007 and 2014, 1 week to 5 years after surgery. Histopathology revealed 29 medulloblastomas (WHO IV), 6 ependymomas (WHO II), 2 anaplastic ependymomas (WHO III) and 21 pilocytic astrocytomas (WHO I). ION MR imaging changes were correlated with surgery-to-MR interval and with tumour grading. RESULTS: ION MR imaging changes were observed in 19/64 (33 %), and all consisted of T2 signal alterations, 15 bilateral and four unilateral, with dentate nucleus damage in all cases. Olivary enlargement was observed in few cases only (7/19). ION T2 hyperintensity was always present between 1 and 6 months after surgery with a trend to decrease, becoming faint after 1 year. The Fisher test demonstrated a significant (p = 0.005) correlation between ION MR imaging changes and high tumour grade. CONCLUSIONS: Our results demonstrate that olivary degeneration, with or without hypertrophy, is a relatively frequent consequence of posterior fossa surgery, particularly in children treated for high-grade tumours. Knowledge of this condition can prevent misdiagnoses and unnecessary investigations.