Catatonia superimposed on stiff person syndrome: A clinical conundrum from a neuropsychiatric setting

Stiff person syndrome (SPS) is characterised by severe progressive muscle stiffness, which can be mistaken for immobility and rigidity in catatonia. We present the case of a 72-year-old woman who suffered from progressive stiffness and spasms in her axial muscles and extremities. The psychiatry team was consulted to consider the possibility of a primary psychiatric diagnosis of catatonic depression, given the negative test for Anti-GAD and anti-DPPX antibodies, two of the most common antibodies proposed for the causation of SPS. Assessing, and diagnosing catatonia and depression in SPS is challenging for clinicians, as many symptoms and signs mimic all three conditions. This case illustrates the possibility of the superimposition of catatonia over SPS. A meticulous history, examination, and investigation are imperative to differentiate the conditions. Diagnosing psychiatric disorders is essential for a better outcome and integrated clinical care in SPS.