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Kernohan-Woltman notch phenomenon: an exceptional neurological picture?
R Carrasco Moro1, J M Pascual Garvi2, C Vior Fernández1
1Servicio de Neurocirugía, Hospital Universitario Ramón y Cajal, Madrid, Spain.
Neurologia
|November 17, 2022
Summary
Ipsilateral hemiparesis, often caused by the Kernohan-Woltman notch phenomenon, is frequently linked to traumatic injuries. Magnetic resonance imaging is crucial for diagnosis, with motor evoked potentials aiding in complex cases.
Area of Science:
- Neuroscience
- Neurology
- Neurosurgery
Background:
- Ipsilateral hemiparesis (IH) is a paradoxical neurological dysfunction where motor deficits occur on the same side as the brain lesion.
- The Kernohan-Woltman notch phenomenon (KWNP), caused by corticospinal tract compression, is the primary cause of IH.
- Understanding IH and KWNP is crucial for accurate diagnosis and treatment of specific intracranial pathologies.
Purpose of the Study:
- To analyze epidemiological, clinical, radiological, neurophysiological, and prognostic variables in patients with IH secondary to KWNP.
- To investigate the mechanisms and diagnostic modalities for IH caused by KWNP.
- To compare findings with previous historical series regarding the etiology of KWNP.
Main Methods:
- Retrospective analysis of 12 patients diagnosed with IH secondary to KWNP.
- Inclusion of descriptive data on patient demographics, clinical presentation, imaging findings, and neurophysiological tests.
- Assessment of patient outcomes using the modified Rankin scale.
Main Results:
- Most cases (75%) presented with acute or subacute onset of symptoms.
- Magnetic resonance imaging (MRI) identified structural lesions in the contralateral cerebral peduncle in two-thirds of patients.
- Motor evoked potentials (MEP) showed impairment in 4 patients, and 7 patients improved motor function during follow-up.
Conclusions:
- Traumatic mechanisms were the predominant cause of KWNP in this patient series, differing from historical reports.
- MRI is the optimal imaging modality for detecting the cerebral peduncle notch and underlying corticospinal tract lesions.
- Motor evoked potentials can assist in diagnosing IH, particularly when radiological findings are inconclusive.
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