Short Report
Generalized Myoclonus: A Rare Manifestation of Stroke
The Neurohospitalist 2015, Vol 5(1) 28-31 ª The Author(s) 2013 Reprints and permission: sagepub.com/journalsPermissions.nav DOI: 10.1177/1941874413515679 nhos.sagepub.com
Violiza Inoa, MD1,2, and Louise D. McCullough, MD, PhD3,4,5
Abstract Movement disorders have been reported as rare complications of stroke. The basal ganglia have been implicated in the pathophysiology of most post-stroke dyskinesias. We outline different types of post-stroke myoclonus and their possible pathophysiology. A middle-aged man developed generalized myoclonus after an ischemic stroke in the superior midbrain and subthalamic nuclei. Spontaneous resolution was seen by 72 hours. A lesion to the subthalamic nuclei disrupted the normal thalamic inhibition, which likely led to the involuntary movements seen in our patient. In this case, myoclonus was generalized, which, to the best of our knowledge, has not been reported in the literature as a direct consequence of focal stroke. Keywords stroke, cerebrovascular disorders, movement disorders, clinical specialty, stroke and cerebrovascular disease, clinical specialty
Movement disorders are rare complications of stroke. These can manifest as either long-term sequelae (usually after motor function has been partially or totally regained) or, less commonly, an immediate consequence of brain ischemia or hemorrhage. We report a case of a 61-year-old man with controlled hypertension on metroprolol who was found unresponsive in his home. He was initially transferred by ambulance to an outside hospital, where a nonenhanced head computed tomography (CT) was negative. He was given phenytoin 1000 mg intravenously (IV) and decadron 20 mg IV prior to arrival at our center. On our initial neurologic examination performed 3.5 hours after he was found unresponsive, he was stuporous and not responding to commands. He was withdrawing to pain in all 4 extremities and an extensor plantar reflex was noted on the right. Cranial nerves showed fixed and unequal pupils (right 5 mm and left 2 mm), left eye hypertropia, and right eye exotropia. Corneal and gag reflexes were present. No involuntary movements were appreciated. His National Institutes of Health Stroke Scale score was 22. General examination revealed an irregular heart rate and a blood pressure of 131/76 mm Hg. His electrocardiography showed atrial fibrillation. He was intubated immediately for airway protection after apneic breathing episodes were noted. Rocuronium was used for intubation, and he was premedicated with lidocaine and etomidate. After intubation, a single propofol bolus was given for transient hypertension and agitation. His oxygen saturation remained over 95% at all times. Urine toxicology and serum biochemistry that included a basic metabolic panel, cardiac, and liver enzymes were normal, except for the serum creatine kinase level that was found to be elevated (ie, 748 IU/L). A repeat nonenhanced head CT showed
areas of hypoattenuation in the brain stem. Subsequent CT angiography was normal, with no evidence of large-vessel stenosis or embolus. Brain magnetic resonance imaging (MRI) showed clear evidence of restricted diffusion in the right and superior aspects of the midbrain, extending bilaterally upward into the subthalamic nuclei, which was also seen on fluidattenuated inversion recovery imaging (Figure 1). Thrombolytic agents were not given due to the unclear time of onset (Figure 1). Within the next few hours, the patient developed rapid, involuntary jerking involving primarily his trunk and upper extremities, with minimal extension into his lower extremities. The movements were brief, synchronous, rhythmic, and consistent with myoclonic jerks (see supplemental video). These were episodic and as frequent as 1 per second. These were not ameliorated with Keppra or propofol administration. An electroencephalography (EEG) showed moderate diffuse encephalopathy without focal or epileptiform discharges. No EEG changes were associated with these intermittent body 1 Department of Neurology. Beth Israel Deaconess Medical Center, Boston, MA, USA 2 Harvard Medical School, Boston, MA, USA 3 Department of Neurology. The University of Connecticut Health Center, Farmington, CT, USA 4 Hartford Hospital, Hartford, CT, USA 5 University of Connecticut, Farmington, CT, USA
Corresponding Author: Violiza Inoa, Beth Israel Deaconess Medical Center, 330 Brookline Ave, Boston, MA 02215, USA. Email: [email protected]
Downloaded from nho.sagepub.com at UNIV OF GEORGIA LIBRARIES on May 31, 2015
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Figure 1. Diffusion-weighted MRI sequences demonstrate an acute stroke affecting the right and upper midbrain (1A and 1B) and subthalamic nuclei (1C). Restricted diffusion demonstrated within the same areas on apparent diffusion coefficient images (2A, 2B, and 2C). Corresponding FLAIR imaging at the same levels on MRI performed 3 weeks later (3A, 3B, and 3C). FLAIR indicates fluid-attenuated inversion recovery; MRI, magnetic resonance imaging.
twitches. Over the course of the next 24 hours, the frequency decreased steadily. By day 2, the myoclonus was stimulus sensitive only. Spontaneous resolution was seen by 72 hours.
Discussion Myoclonus has been described in the literature as a rare complication of stroke and, to date, there are no reports of generalized myoclonus in this context.1-3 The anatomical correlate is unclear. Although no specific topographical location has been described,2 it has been proposed that lesions to the brain stem and/or deep cerebellar nuclei with subsequent interruption of any fiber system in the dentato-rubro-olivary circuit
(Guillain-Mollaret triangle) may be the etiology for this myoclonus.4 An ‘‘intention-and-action myoclonus’’ has been reported in a patient with a thalamic angioma.5 Concomitant myoclonus and tremor after an infarct of the contralateral ventral portion of the left thalamus and subthalamic nucleus have also been described.3 Palatal myoclonus has been reported in pontine stroke,6 and ‘‘focal reflex myoclonus’’ was reported in 1 patient with a large left middle cerebral artery stroke, although the involvement of deeper basal ganglia structures was not established.7 Lesions to the basal ganglia are most frequently implicated in post-stroke movement disorders.1-3 Focal lesions interrupting either the direct or the indirect pathways could result in a variety of movement disorders.2 None
Downloaded from nho.sagepub.com at UNIV OF GEORGIA LIBRARIES on May 31, 2015
30
The Neurohospitalist 5(1)
of the reported dyskinesias have been attributed to any specific site, except for the ‘‘jerky dystonic unsteady hand,’’ which has been described as a manifestation of lesions involving the posterior thalamic nuclei. The authors8 described a ‘‘myoclonic complex hyperkinetic syndrome’’—consisting of myoclonus, ataxia, tremor, dystonia, and chorea—which occurred as a delayed manifestation of a stroke in the posterior choroidal artery distribution involving the posterior thalamus. Although hemichorea–hemiballismus is a well-documented manifestation of lesions in the contralateral subthalamic nucleus and/or its connections,9,10 injury to other basal ganglia structures has also been associated with these dyskinesias, even without the involvement of the subthalamic region or its fibers—a finding that supports the lack of specificity of this particular area for hemichorea or hemiballism. Our patient did not present with chorea–ballism, despite the involvement of the subthalamic nuclei, which again reflects how nonspecific these structures are for any specific movement disorder. Lesions in the subthalamic nucleus are presumed to decrease the normal inhibitory drive of the internal globus pallidus on the thalamus, allowing thalamic outputs to excite the cortex, which leads to involuntary production of movement. Lesions to the red nucleus, which were also present in our patient, have been associated with the occurrence of spontaneous tremors. Tremor-producing lesions must involve cerebellothalamic and nigrostriatal fibers, in addition to the parvocellular division of the red nucleus in primates.11 Given the known association of the dentato-rubro-olivary pathway with the pathogenesis of palatal myoclonus,12-14 one could implicate a lesion of the red nucleus as a contributing factor in the origin of our patient’s myoclonus. To the best of our knowledge, generalized myoclonus has not been described following red nucleus lesions, and this could be a subject of further investigation. The list of possible disorders leading to myoclonus has been well classified by Fahn and colleagues15; and based on the etiology, myoclonus can be characterized as essential, physiologic, epileptic, or symptomatic. Other potential causes of our patient’s myoclonus, besides what has been proposed, include epileptic myoclonus, metabolic or drug-induced myoclonus, and acute post-hypoxic myoclonus. Overall his metabolic workup was unremarkable. Initially, he was administered drugs that have been associated with myoclonus. Phenytoin-related myoclonus is usually dose dependent and associated with toxic levels. This patient received only a loading dose and had no liver or renal impairment. Dyskinesias have been reported with the use of phenytoin in the setting of documented thalamic infarctions in 2 patients.16 The authors described a dyskinesia/hyperkinesia syndrome and the mechanism related to pathways connecting the thalamic and the subthalamic nuclei. Although the character of the syndrome that was described differed from that seen in our case, we think this is relevant due to the similarities in the proposed mechanism and anatomical location. Myoclonus can also be caused by etomidate, but this is brief, lasting less than 2 minutes. The myoclonus duration in our patient was over 72
hours, making it less likely to be related to this medication. Acute post-hypoxic myoclonus is common but is unlikely to be the etiology of the involuntary movements in our case, since this condition is more often seen as a complication of a severe hypoxic event in deeply comatose patients.17 Our patient did not sustain any witnessed episodes of hypoxia; however, it is possible that these occurred prior to his transport to the emergency department. The most compelling evidence against diffuse hypoxic injury is that this patient was able to follow one-step commands on the second day after his stroke, during his episodes of myoclonus. An EEG at that time was relatively normal and his MRI did not show evidence of global anoxic injury. When persistent, acute post-hypoxic myoclonus is sometimes termed myoclonic status epilepticus or myoclonus status. The prognosis of patients with myoclonus status is extremely poor and must influence the decision to withdraw life support when present in comatose patients after cardiac arrest,18,19 but careful evaluation allowed for more cautious optimistic outcome in this case. The development of myoclonus can also occur well after the initial insult, which has been known as Lance-Adams syndrome. This is a persistent, intractable action or intention myoclonus that starts days to weeks after resuscitation in patients who regain consciousness after a hypoxic event.20 Our patient developed acute myoclonus within a few hours after the infarct, which resolved within 72 hours. At evaluation 4 months after his stroke, he was able to follow commands but had moderate disability primarily due to significant dysarthria, swallowing difficulties, and a residual (3 of 5) right hemiparesis. In conclusion, post-stroke movement disorders have been reported but are extremely rare. More than any other structure, the basal ganglia has been implicated in the pathophysiology of a variety of post-stroke dyskinesias. There is no single lesion restricted to a particular movement disorder, except for posterior thalamic lesions responsible for ‘‘jerky dystonic unsteady hand,’’ described previously. Our patient presented with self-limited, generalized myoclonus in the setting of acute stroke, a finding that has not been reported in the literature to date. We believe that our patient’s lesions in the subthalamic nuclei disrupted normal inhibition to the thalamus, allowing for continuous cortical stimuli, with the subsequent production of involuntary movement in the form of generalized myoclonus. Declaration of Conflicting Interests The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding The authors received no financial support for the research, authorship, and/or publication of this article.
Supplemental Material The online video is available at http://XXX.sagepub.com/ supplemental
Downloaded from nho.sagepub.com at UNIV OF GEORGIA LIBRARIES on May 31, 2015
Inoa and McCullough
31
References 1. Handley A, Medcalf P, Hellier K, Dutta D. Movement disorders after stroke. Age Ageing. 2009;38(3):260-266. 2. Ghika-Schmid F, Ghika J, Regli F, Bogousslavsky J. Hyperkinetic movement disorders during and after acute stroke: the Lausanne stroke registry. J Neurol Sci. 1997;146(2):109-116. 3. Kao YF, Shih PY, Chen WH. An unusual concomitant tremor and myoclonus after a contralateral infarct at thalamus and subthalamic nucleus. Kaohsiung J Med Sci. 1999;15(9):562-566. 4. Kinoshita M, Satoyoshi E, Araki Y. Palato-pharyngo-laryngeal myoclonus. Nippon Rinsho. 1993;51(11):2989-2994. 5. Avanzini G, Broggi G, Caraceni T. Intention and action myoclonus from thalamic angioma. report of a case. Eur Neurol. 1977; 15(4):194-202. 6. Fabiani G, Teive HA, Sa´ D, et al. Palatal myoclonus: report of two cases. Arq Neuropsiquiatr. 2000;58(3B):901-904. 7. Sutton GG, Mayer RF. Focal reflex myoclonus. J Neurol Neurosurg Psychiatry. 1974;37(2):207-217. 8. Ghika J, Bogousslavsky J, Henderson J, Maeder P, Regli F. The ‘jerky dystonic unsteady hand’: Delayed motor syndrome in posterior thalamic infarctions. J Neurol. 1994;241(9):537-542. 9. Carpenter MB. Ballism associated with partial destruction of the subthalamic nucleus of luys. Neurology. 1955;5(7):479-489. 10. Carpenter MB, Whittier JR, Mettler FA. Analysis of choreoid hyperkinesia in the rhesus monkey. Surgical and pharmacological analysis of hyperkinesia resulting from lesions in the subthalamic nucleus of luys. J Comp Neurol. 1950;92(3):293-331.
11. Ohye C, Shibazaki T, Hirai T, et al. A special role of the parvocellular red nucleus in lesion-induced spontaneous tremor in monkeys. Behav Brain Res. 1988;28(1-2):241-243. 12. Mastaglia FL, Grainger KMR, Kakulas BA. Palatal myoclonus and associated movements. Proc Aust Assoc Neurol. 1974;11: 183-187. 13. Turazzi S, Alexandre A, Bricolo A, Rizzuto N. Opsoclonus and palatal myoclonus during prolonged post traumatic coma. a clinico pathologic study. Eur Neurol. 1977;15(5):257-263. 14. Chua HC, Tan AKY, Venketasubramanian N, Tan CB, Tjia H. Palatal myoclonus—a case report. Ann Acad Med Singapore. 1999;28(4):593-595. 15. Fahn S, Marsden CD, Van Woert MH. Definition and classification of myoclonus. Adv Neur. 1986;43:1-5. 16. Harrison MB. Phenytoin and dyskinesias: a report of two cases and review of the literature. Mov Dis. 1993;8(1):19-27. 17. Hallett M. Physiology of human posthypoxic myoclonus. Mov Disord. 2000;15(suppl 1):8-13. 18. Wijdicks EFM, Parisi JE, Sharbrough FW. Prognostic value of myoclonus status in comatose survivors of cardiac arrest. Ann Neurol. 1994;35(2):239-243. 19. Hui ACF, Cheng C, Lam A, Mok V, Joynt GM. Prognosis following postanoxic myoclonus status epilepticus. Eur Neurol. 2005;54(1):10-13. 20. Lance JW, Adams RD. The syndrome of intention or action myoclonus as s sequel to hypoxic encephalopathy. Brain. 1963;86:111-136.
Downloaded from nho.sagepub.com at UNIV OF GEORGIA LIBRARIES on May 31, 2015
Generalized Myoclonus: A Rare Manifestation of Stroke
The Neurohospitalist 2015, Vol 5(1) 28-31 ª The Author(s) 2013 Reprints and permission: sagepub.com/journalsPermissions.nav DOI: 10.1177/1941874413515679 nhos.sagepub.com
Violiza Inoa, MD1,2, and Louise D. McCullough, MD, PhD3,4,5
Abstract Movement disorders have been reported as rare complications of stroke. The basal ganglia have been implicated in the pathophysiology of most post-stroke dyskinesias. We outline different types of post-stroke myoclonus and their possible pathophysiology. A middle-aged man developed generalized myoclonus after an ischemic stroke in the superior midbrain and subthalamic nuclei. Spontaneous resolution was seen by 72 hours. A lesion to the subthalamic nuclei disrupted the normal thalamic inhibition, which likely led to the involuntary movements seen in our patient. In this case, myoclonus was generalized, which, to the best of our knowledge, has not been reported in the literature as a direct consequence of focal stroke. Keywords stroke, cerebrovascular disorders, movement disorders, clinical specialty, stroke and cerebrovascular disease, clinical specialty
Movement disorders are rare complications of stroke. These can manifest as either long-term sequelae (usually after motor function has been partially or totally regained) or, less commonly, an immediate consequence of brain ischemia or hemorrhage. We report a case of a 61-year-old man with controlled hypertension on metroprolol who was found unresponsive in his home. He was initially transferred by ambulance to an outside hospital, where a nonenhanced head computed tomography (CT) was negative. He was given phenytoin 1000 mg intravenously (IV) and decadron 20 mg IV prior to arrival at our center. On our initial neurologic examination performed 3.5 hours after he was found unresponsive, he was stuporous and not responding to commands. He was withdrawing to pain in all 4 extremities and an extensor plantar reflex was noted on the right. Cranial nerves showed fixed and unequal pupils (right 5 mm and left 2 mm), left eye hypertropia, and right eye exotropia. Corneal and gag reflexes were present. No involuntary movements were appreciated. His National Institutes of Health Stroke Scale score was 22. General examination revealed an irregular heart rate and a blood pressure of 131/76 mm Hg. His electrocardiography showed atrial fibrillation. He was intubated immediately for airway protection after apneic breathing episodes were noted. Rocuronium was used for intubation, and he was premedicated with lidocaine and etomidate. After intubation, a single propofol bolus was given for transient hypertension and agitation. His oxygen saturation remained over 95% at all times. Urine toxicology and serum biochemistry that included a basic metabolic panel, cardiac, and liver enzymes were normal, except for the serum creatine kinase level that was found to be elevated (ie, 748 IU/L). A repeat nonenhanced head CT showed
areas of hypoattenuation in the brain stem. Subsequent CT angiography was normal, with no evidence of large-vessel stenosis or embolus. Brain magnetic resonance imaging (MRI) showed clear evidence of restricted diffusion in the right and superior aspects of the midbrain, extending bilaterally upward into the subthalamic nuclei, which was also seen on fluidattenuated inversion recovery imaging (Figure 1). Thrombolytic agents were not given due to the unclear time of onset (Figure 1). Within the next few hours, the patient developed rapid, involuntary jerking involving primarily his trunk and upper extremities, with minimal extension into his lower extremities. The movements were brief, synchronous, rhythmic, and consistent with myoclonic jerks (see supplemental video). These were episodic and as frequent as 1 per second. These were not ameliorated with Keppra or propofol administration. An electroencephalography (EEG) showed moderate diffuse encephalopathy without focal or epileptiform discharges. No EEG changes were associated with these intermittent body 1 Department of Neurology. Beth Israel Deaconess Medical Center, Boston, MA, USA 2 Harvard Medical School, Boston, MA, USA 3 Department of Neurology. The University of Connecticut Health Center, Farmington, CT, USA 4 Hartford Hospital, Hartford, CT, USA 5 University of Connecticut, Farmington, CT, USA
Corresponding Author: Violiza Inoa, Beth Israel Deaconess Medical Center, 330 Brookline Ave, Boston, MA 02215, USA. Email: [email protected]
Downloaded from nho.sagepub.com at UNIV OF GEORGIA LIBRARIES on May 31, 2015
Inoa and McCullough
29
Figure 1. Diffusion-weighted MRI sequences demonstrate an acute stroke affecting the right and upper midbrain (1A and 1B) and subthalamic nuclei (1C). Restricted diffusion demonstrated within the same areas on apparent diffusion coefficient images (2A, 2B, and 2C). Corresponding FLAIR imaging at the same levels on MRI performed 3 weeks later (3A, 3B, and 3C). FLAIR indicates fluid-attenuated inversion recovery; MRI, magnetic resonance imaging.
twitches. Over the course of the next 24 hours, the frequency decreased steadily. By day 2, the myoclonus was stimulus sensitive only. Spontaneous resolution was seen by 72 hours.
Discussion Myoclonus has been described in the literature as a rare complication of stroke and, to date, there are no reports of generalized myoclonus in this context.1-3 The anatomical correlate is unclear. Although no specific topographical location has been described,2 it has been proposed that lesions to the brain stem and/or deep cerebellar nuclei with subsequent interruption of any fiber system in the dentato-rubro-olivary circuit
(Guillain-Mollaret triangle) may be the etiology for this myoclonus.4 An ‘‘intention-and-action myoclonus’’ has been reported in a patient with a thalamic angioma.5 Concomitant myoclonus and tremor after an infarct of the contralateral ventral portion of the left thalamus and subthalamic nucleus have also been described.3 Palatal myoclonus has been reported in pontine stroke,6 and ‘‘focal reflex myoclonus’’ was reported in 1 patient with a large left middle cerebral artery stroke, although the involvement of deeper basal ganglia structures was not established.7 Lesions to the basal ganglia are most frequently implicated in post-stroke movement disorders.1-3 Focal lesions interrupting either the direct or the indirect pathways could result in a variety of movement disorders.2 None
Downloaded from nho.sagepub.com at UNIV OF GEORGIA LIBRARIES on May 31, 2015
30
The Neurohospitalist 5(1)
of the reported dyskinesias have been attributed to any specific site, except for the ‘‘jerky dystonic unsteady hand,’’ which has been described as a manifestation of lesions involving the posterior thalamic nuclei. The authors8 described a ‘‘myoclonic complex hyperkinetic syndrome’’—consisting of myoclonus, ataxia, tremor, dystonia, and chorea—which occurred as a delayed manifestation of a stroke in the posterior choroidal artery distribution involving the posterior thalamus. Although hemichorea–hemiballismus is a well-documented manifestation of lesions in the contralateral subthalamic nucleus and/or its connections,9,10 injury to other basal ganglia structures has also been associated with these dyskinesias, even without the involvement of the subthalamic region or its fibers—a finding that supports the lack of specificity of this particular area for hemichorea or hemiballism. Our patient did not present with chorea–ballism, despite the involvement of the subthalamic nuclei, which again reflects how nonspecific these structures are for any specific movement disorder. Lesions in the subthalamic nucleus are presumed to decrease the normal inhibitory drive of the internal globus pallidus on the thalamus, allowing thalamic outputs to excite the cortex, which leads to involuntary production of movement. Lesions to the red nucleus, which were also present in our patient, have been associated with the occurrence of spontaneous tremors. Tremor-producing lesions must involve cerebellothalamic and nigrostriatal fibers, in addition to the parvocellular division of the red nucleus in primates.11 Given the known association of the dentato-rubro-olivary pathway with the pathogenesis of palatal myoclonus,12-14 one could implicate a lesion of the red nucleus as a contributing factor in the origin of our patient’s myoclonus. To the best of our knowledge, generalized myoclonus has not been described following red nucleus lesions, and this could be a subject of further investigation. The list of possible disorders leading to myoclonus has been well classified by Fahn and colleagues15; and based on the etiology, myoclonus can be characterized as essential, physiologic, epileptic, or symptomatic. Other potential causes of our patient’s myoclonus, besides what has been proposed, include epileptic myoclonus, metabolic or drug-induced myoclonus, and acute post-hypoxic myoclonus. Overall his metabolic workup was unremarkable. Initially, he was administered drugs that have been associated with myoclonus. Phenytoin-related myoclonus is usually dose dependent and associated with toxic levels. This patient received only a loading dose and had no liver or renal impairment. Dyskinesias have been reported with the use of phenytoin in the setting of documented thalamic infarctions in 2 patients.16 The authors described a dyskinesia/hyperkinesia syndrome and the mechanism related to pathways connecting the thalamic and the subthalamic nuclei. Although the character of the syndrome that was described differed from that seen in our case, we think this is relevant due to the similarities in the proposed mechanism and anatomical location. Myoclonus can also be caused by etomidate, but this is brief, lasting less than 2 minutes. The myoclonus duration in our patient was over 72
hours, making it less likely to be related to this medication. Acute post-hypoxic myoclonus is common but is unlikely to be the etiology of the involuntary movements in our case, since this condition is more often seen as a complication of a severe hypoxic event in deeply comatose patients.17 Our patient did not sustain any witnessed episodes of hypoxia; however, it is possible that these occurred prior to his transport to the emergency department. The most compelling evidence against diffuse hypoxic injury is that this patient was able to follow one-step commands on the second day after his stroke, during his episodes of myoclonus. An EEG at that time was relatively normal and his MRI did not show evidence of global anoxic injury. When persistent, acute post-hypoxic myoclonus is sometimes termed myoclonic status epilepticus or myoclonus status. The prognosis of patients with myoclonus status is extremely poor and must influence the decision to withdraw life support when present in comatose patients after cardiac arrest,18,19 but careful evaluation allowed for more cautious optimistic outcome in this case. The development of myoclonus can also occur well after the initial insult, which has been known as Lance-Adams syndrome. This is a persistent, intractable action or intention myoclonus that starts days to weeks after resuscitation in patients who regain consciousness after a hypoxic event.20 Our patient developed acute myoclonus within a few hours after the infarct, which resolved within 72 hours. At evaluation 4 months after his stroke, he was able to follow commands but had moderate disability primarily due to significant dysarthria, swallowing difficulties, and a residual (3 of 5) right hemiparesis. In conclusion, post-stroke movement disorders have been reported but are extremely rare. More than any other structure, the basal ganglia has been implicated in the pathophysiology of a variety of post-stroke dyskinesias. There is no single lesion restricted to a particular movement disorder, except for posterior thalamic lesions responsible for ‘‘jerky dystonic unsteady hand,’’ described previously. Our patient presented with self-limited, generalized myoclonus in the setting of acute stroke, a finding that has not been reported in the literature to date. We believe that our patient’s lesions in the subthalamic nuclei disrupted normal inhibition to the thalamus, allowing for continuous cortical stimuli, with the subsequent production of involuntary movement in the form of generalized myoclonus. Declaration of Conflicting Interests The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding The authors received no financial support for the research, authorship, and/or publication of this article.
Supplemental Material The online video is available at http://XXX.sagepub.com/ supplemental
Downloaded from nho.sagepub.com at UNIV OF GEORGIA LIBRARIES on May 31, 2015
Inoa and McCullough
31
References 1. Handley A, Medcalf P, Hellier K, Dutta D. Movement disorders after stroke. Age Ageing. 2009;38(3):260-266. 2. Ghika-Schmid F, Ghika J, Regli F, Bogousslavsky J. Hyperkinetic movement disorders during and after acute stroke: the Lausanne stroke registry. J Neurol Sci. 1997;146(2):109-116. 3. Kao YF, Shih PY, Chen WH. An unusual concomitant tremor and myoclonus after a contralateral infarct at thalamus and subthalamic nucleus. Kaohsiung J Med Sci. 1999;15(9):562-566. 4. Kinoshita M, Satoyoshi E, Araki Y. Palato-pharyngo-laryngeal myoclonus. Nippon Rinsho. 1993;51(11):2989-2994. 5. Avanzini G, Broggi G, Caraceni T. Intention and action myoclonus from thalamic angioma. report of a case. Eur Neurol. 1977; 15(4):194-202. 6. Fabiani G, Teive HA, Sa´ D, et al. Palatal myoclonus: report of two cases. Arq Neuropsiquiatr. 2000;58(3B):901-904. 7. Sutton GG, Mayer RF. Focal reflex myoclonus. J Neurol Neurosurg Psychiatry. 1974;37(2):207-217. 8. Ghika J, Bogousslavsky J, Henderson J, Maeder P, Regli F. The ‘jerky dystonic unsteady hand’: Delayed motor syndrome in posterior thalamic infarctions. J Neurol. 1994;241(9):537-542. 9. Carpenter MB. Ballism associated with partial destruction of the subthalamic nucleus of luys. Neurology. 1955;5(7):479-489. 10. Carpenter MB, Whittier JR, Mettler FA. Analysis of choreoid hyperkinesia in the rhesus monkey. Surgical and pharmacological analysis of hyperkinesia resulting from lesions in the subthalamic nucleus of luys. J Comp Neurol. 1950;92(3):293-331.
11. Ohye C, Shibazaki T, Hirai T, et al. A special role of the parvocellular red nucleus in lesion-induced spontaneous tremor in monkeys. Behav Brain Res. 1988;28(1-2):241-243. 12. Mastaglia FL, Grainger KMR, Kakulas BA. Palatal myoclonus and associated movements. Proc Aust Assoc Neurol. 1974;11: 183-187. 13. Turazzi S, Alexandre A, Bricolo A, Rizzuto N. Opsoclonus and palatal myoclonus during prolonged post traumatic coma. a clinico pathologic study. Eur Neurol. 1977;15(5):257-263. 14. Chua HC, Tan AKY, Venketasubramanian N, Tan CB, Tjia H. Palatal myoclonus—a case report. Ann Acad Med Singapore. 1999;28(4):593-595. 15. Fahn S, Marsden CD, Van Woert MH. Definition and classification of myoclonus. Adv Neur. 1986;43:1-5. 16. Harrison MB. Phenytoin and dyskinesias: a report of two cases and review of the literature. Mov Dis. 1993;8(1):19-27. 17. Hallett M. Physiology of human posthypoxic myoclonus. Mov Disord. 2000;15(suppl 1):8-13. 18. Wijdicks EFM, Parisi JE, Sharbrough FW. Prognostic value of myoclonus status in comatose survivors of cardiac arrest. Ann Neurol. 1994;35(2):239-243. 19. Hui ACF, Cheng C, Lam A, Mok V, Joynt GM. Prognosis following postanoxic myoclonus status epilepticus. Eur Neurol. 2005;54(1):10-13. 20. Lance JW, Adams RD. The syndrome of intention or action myoclonus as s sequel to hypoxic encephalopathy. Brain. 1963;86:111-136.
Downloaded from nho.sagepub.com at UNIV OF GEORGIA LIBRARIES on May 31, 2015
