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Kernohan's notch phenomenon in chronic subdural hematoma: MRI findings
Kyung-Sub Moon1, Jung-Kil Lee, Sung-Pil Joo
1Department of Neurosurgery, Chonnam National University Hospital and Medical School, 8 Hack-Dong, Dong-Ku, 501-757, Gwangju, Korea.
Abstract:
We report two cases of Kernohan's notch phenomenon secondary to chronic subdural hematoma detected by MRI. In the first case, the patient was drowsy with an oculomotor palsy and a hemiparesis ipsilateral to the chronic subdural hematoma. MRI in the post-operative period showed no abnormal signal or deformity of the crus cerebri. The neurological signs immediately resolved after trephination. In the second case, the patient was admitted with progressive decrease in their level of consciousness and ipsilateral hemiparesis with the chronic subdural hematoma. MRI on admission revealed an abnormal signal in the contralateral crus cerebri against the chronic subdural hematoma. After surgery, the mental state gradually recovered to normal with some degree of residual hemiparesis. In patients with chronic subdural hematoma, a compressive deformity of the crus cerebri, without abnormal signal on MRI, may predict a better neurological recovery in patients with Kernohan's notch phenomenon.
Insights
Kernohan's notch phenomenon from chronic subdural hematoma can cause neurological deficits. MRI findings of the crus cerebri may predict patient recovery outcomes.
Area of Science:
- Neurology
- Neurosurgery
- Radiology
Background:
- Kernohan's notch phenomenon (KNP) is a rare neurological condition.
- It typically presents as hemiparesis contralateral to a supratentorial mass lesion.
- Chronic subdural hematoma (CSDH) is a potential, though uncommon, cause of KNP.
Observation:
- Two cases of KNP secondary to CSDH are presented.
- Case 1: Patient presented with drowsiness, oculomotor palsy, and ipsilateral hemiparesis. Post-operative MRI showed no crus cerebri abnormality; neurological signs resolved after surgery.
- Case 2: Patient presented with decreased consciousness and ipsilateral hemiparesis. Pre-operative MRI revealed contralateral crus cerebri signal abnormality; partial recovery occurred post-surgery.
Findings:
- CSDH can cause KNP through uncal herniation compressing the crus cerebri.
- The presence or absence of abnormal MRI signals in the crus cerebri may correlate with the severity of compression.
- Absence of abnormal MRI signals in the crus cerebri may indicate a less severe or reversible compression.
Implications:
- MRI assessment of the crus cerebri is crucial in patients with CSDH and KNP.
- Identifying crus cerebri compression patterns on MRI can aid in predicting neurological recovery.
- Prompt surgical intervention (trephination) is vital for improving outcomes in CSDH-induced KNP.
