Disclosures: Chase J. Smith, DO: Nothing to disclose

Case Description: A patient with hypertension and dyslipidemia presented to the ED with a week of right upper extremity weakness, progressing to right hemiparesis causing mechanical fall. Initial stroke work-up was negative, but laboratory studies were remarkable for hypercalcemia. Outpatient follow-up MRI brain revealed chronic microvascular changes, with further focus made on hypercalcemia as suspected cause for weakness. He suffered another fall, was admitted and diagnosed with primary hyperparathyroidism due to papillary thyroid carcinoma. Patient underwent total thyroidectomy without improvement in hemiparesis. Further neurologic work-up including CSF studies, infectious, metabolic, and autoimmune etiologies were inconclusive. Chest imaging noted right unilateral hemidiaphragm elevation, suspicious for neuromuscular process. Neurodiagnostics demonstrated widespread axonal loss, denervation and fasciculations noted throughout bilateral upper/lower extremities, bulbar and paraspinal musculature. The patient was diagnosed with motor neuron disease and admitted for inpatient rehabilitation. Two weeks later, his family reported mildly worsened right hemiparesis, fatigue and new urinary incontinence. Urinalysis was negative. No clear falls had been identified since rehab admission. Stat CT head revealed a large acute on subacute subdural hematoma causing >15mm midline shift, with Kernohan’s notch phenomenon. Patient was transferred to neuro ICU with emergent subdural hematoma evacuation. After stabilization, he was readmitted for further rehabilitation of underlying motor neuron disease and post-neurosurgical care.

Setting: Inpatient rehabilitation unit

Patient: 70-year-old male

Assessment/Results: Patients with motor neuron disease may have a variable course of disease progression. Gradual intracranial compression can masquerade as unilateral evolution of lower motor neuron symptoms.

Discussion: Elevated intracranial pressure must be considered for acute motor changes in ambulatory patients with motor neuron disease. Meticulous history, serial exams and low threshold for head imaging in patients with a predisposition to fall can lead to rapid diagnosis of a neurosurgical emergency.

Conclusion: Kernohan’s notch phenomenon can cause ipsilateral hemiparesis, which may be a diagnostic challenge in patients with motor neuron disease.

Level of Evidence: Level V

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/acute-worsening-hemiparesis-in-a-patient-with-motor-neuron-disease-due-to-kernohans-notch-phenomenon-of-evolving-subdural-hematoma-a-case-report/