Parkinsonism after uncal herniation—an overlooked false localizing sign?

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Recognizing parkinsonism in a patient with a pyramidal syndrome can be difficult but has major therapeutic implications. Both parkinsonism and a pyramidal syndrome can be present as a sequelae of uncal herniation. We present a patient with a pyramidal syndrome and concurrent hypokinetic-rigid syndrome secondary to uncal herniation, with an excellent response to levodopa and subthalamic nucleus deep brain stimulation (STN-DBS). A 19-year-old young man was presented to the emergency room after acute loss of consciousness (Glasgow Coma Scale score of 3) and absent pupillary reflexes, resulting from a spontaneous intracerebral hemorrhage and subdural hematoma in the left hemisphere, with a midline shift and uncal herniation (Fig. 1A). Decompressive hemicraniectomy was performed. The level of consciousness slowly improved during hospital admission. Six months after presentation, a left-sided paresis with remarkable hypertonia and hyperreflexia remained, in accordance with a pyramidal syndrome ipsilateral to the hemorrhage (a well-known false-localizing sign secondary to uncal herniation). There was extreme slowness of movement on the left body side with bradykinesia, and a spastic gait with reduced left-sided arm swing (Video 1). Under suspicion of a concurrent hypokinetic-rigid syndrome, a test-trial of levodopa was performed. Bradykinesia dramatically improved (MDS-UPDRS-III off-levodopa 53, on-levodopa 27, 49% improvement, Video 2). The levodopa response lasted for 2 hours. MRI-brain showed abnormalities in the midbrain, most pronounced on the right side, and a dopamine transporter (DAT-SPECT)-scan showed complete loss of uptake on the right side, with moderately reduced uptake on the left side (Fig. 1B,C). Despite levodopa/benserazide 200/50 mg 11 times daily and ropinirol 4 mg twice daily, there were considerable response fluctuations and neuropsychiatric side-effects related to high doses of dopaminergic medication. Therefore, unilateral right-sided STN-DBS implantation was performed. Intraoperative microelectrode recordings at target depth showed increased neuronal background activity with frequent multiunit discharges, similar to what is seen in Parkinson's disease1 (Fig. 1D). At six months follow-up, the patient experienced no motor fluctuations. MDS-UPDRS-III scores were 31 off-levodopa on-DBS, 27 on-levodopa on-DBS, 46 on-levodopa off-DBS and 50 off-levodopa off-DBS. For additional clinical information please see the supplementary materials. This is a unique case of vascular parkinsonism after intracerebral hemorrhage, secondary to substantia nigra damage due to uncal herniation. The phenomenon of midbrain-damage due to uncal herniation is referred to as Kernohan's notch phenomenon. We hypothesize that midbrain-damage, which was most pronounced on the right side, caused disruption of nigrostriatal neurons. Dopa-responsive hypokinetic-rigid syndrome related to Kernohan's notch phenomenon has been described previously (Table S1).2-5 The substantial response to levodopa was a good predictor for the effectiveness of unilateral STN-DBS. In Parkinson's disease, the therapeutic effect of levodopa and high-frequency stimulation of the STN is thought to occur by means of suppression of pathological beta-oscillations.1 Based on intraoperative microelectrode recordings in our case, we hypothesize that similar mechanisms are involved in other forms of nigrostriatal damage such as vascular parkinsonism. In conclusion, a hypokinetic-rigid syndrome may result from uncal herniation. Its recognition may have tremendous therapeutic consequences as the response to both levodopa and DBS can be excellent. (1) Research project: A. Conception, B. Organization, C. Execution; (2) Statistical Analysis: A. Design, B. Execution, C. Review and Critique; (3) Manuscript: A. Writing of the first draft, B. Review and Critique. A.W.G.B.: 1A, 1B, 1C, 3A. S.V.: 1B, 1C, 3B. P.R.S.: 1C, 3B. A.I.: 3B. J.M.D.: 1A, 1C, 3B. Ethical Compliance Statement: The authors confirm that approval of an institutional review board was not required for this work. Informed consent from the patient is obtained. 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 Conflicts of Interest: The authors declare that there are no funding sources or conflicts of interest to report. Financial Disclosures of all authors (for the preceding 12 months): Dr. Buijink received funding from the Netherlands Organisation for Health Research and Development (ZonMw Off Road grant #04510012210044). Dr. Dijk has received unrestricted grants from Netherlands Organisation for Health Research and Development (ZonMw) and Medtronic for the INVEST study, a comparative study of treatment with deep brain stimulation (DBS) and continuous levodopa carbidopa intestinal gel infusion in Parkinson's disease and an unrestricted grant from Amsterdam Neuroscience for imaging in neuropathic tremor. Dr. Schuurman reported personal fees from Medtronic and Boston Scientific during the conduct of the study. No other disclosures were reported. TABLE S1. Published cases of secondary parkinsonism after acute intracranial hemorrhage, in comparison to our case. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. 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