The posterior fossa syndrome questionnaire: using science to inform practice

Up to 34% of patients with medulloblastoma develop posterior fossa syndrome (PFS) following brain tumor resection and have increased risk of long-term neurocognitive impairments. Lack of agreement in conceptualization and diagnosis of PFS calls for improvements in diagnostic methods. The current study aimed to describe psychometric properties of a new posterior fossa syndrome questionnaire (PFSQ).

The PFSQ was informed by prior research and developed by a multidisciplinary team with subject matter expertise. Participants (N = 164; 63.4% Male; 78.7% White; M_{age at diagnosis} = 10.38 years, SD = 5.09, range 3-31 years) included patients with newly diagnosed medulloblastoma enrolled in the SJMB12 clinical trial. Forty-four patients (26.8%) were classified as having PFS based on attending physician's post-surgical yes/no report. A PFSQ was completed by a neurologist within 2 weeks of coming to St. Jude Children's Research Hospital for adjuvant treatment, irrespective of suspicion for PFS.

PFSQ items ataxia (100.00%), dysmetria (95.45%), and speech/language changes (79.55%) were most sensitive. However, ataxia (26.50%) and dysmetria (46.61%) demonstrated low specificity. Speech/language changes (81.36%), mutism (95.76%), orofacial apraxia (98.29%) and irritability (96.61%) had high specificity. A principal component analysis found four components: (1) speech/language changes, (2) apraxias (including mutism), (3) motor/oromotor, and (4) emotional lability.

The PFSQ is a dimensional diagnostic approach that can be used to improve diagnostic consistency across clinical and research groups to help accelerate understanding of PFS etiology, identify surgical correlates of risk, predict long-term impairments, and develop targeted interventions. Additional measure validation, including correlation with symptom resolution, is required.