To the Editor: Urinary incontinence may be a feature of bilateral subdural hemorrhage in patients who have no lateralizing signs. Although urinary incontinence and gait disturbance did not feature among the characteristics of 47 patients with intracranial hemorrhage, 32 of whom had subdural hematoma (SDH),1 even in the absence of lateralizing signs, identification of the triad of intellectual deterioration, new-onset urinary incontinence, and gait disturbance can aid diagnosis of bilateral subdural hematoma.2 In the latter study, of 10 subjects with bilateral subdural hematoma, six were aged 46 to 77, with concurrent urinary incontinence associated with mild headache and intellectual deterioration. Lateralizing signs were not documented, but all six exhibited unsteady gait. Although the temporal relationship between subdural hematoma and onset of urinary incontinence was also not documented, the authors of the study reported that “all patients had excellent recovery after removal of the hematoma.”2 In another report of bilateral subdural hematoma, the onset of urinary incontinence was 2 days before admission, and its presence was associated with obtundation and akinetic mutism. After evacuation of the hematoma “he regained his pre-operative level of function.”3 SDH-associated urinary incontinence is not necessarily associated with obtundation, however. In one report, only three of the six patients with incontinence and bilateral chronic SDH became stuporous or somnolent,2 and in another report, all eight patients with chronic SDH were documented as being fully conscious.4
SDH-associated urinary incontinence is most probably attributable to neurological damage involving a putative supratentorial micturition center whose components include bilateral cortical regions located in the anterior part of the frontal lobe near the midline.5 Accordingly, in elderly fallers without focal findings and in whom only head trauma is capable of differentiating between presence and absence of traumatic intracranial hemorrhage,1 it is worthwhile to make a specific inquiry, in the first instance, about new-onset urinary incontinence because, especially in the nursing home population, this symptom might be more easily identifiable than intellectual deterioration or gait disturbance. Although this is a line of inquiry that runs counter to the proposition that “urinary incontinence … is usually not encountered in chronic subdural hematoma,”6 it is worth noting that, in a study comprising 500 consecutive cases of chronic SDH (including 88 with bilateral SDH), the majority of whom were aged 60 and older, urinary incontinence was a feature in 87 cases (17.4%), being associated with gait disturbance in 80 of those instances.7 In that study, head injury was the underlying cause in 286 instances and, in 148 cases, was attributable to a fall while walking. Ninety-one percent of the 286 instances of head injury were classified as mild, being associated with Glasgow coma scale 15–13, and as in the study reported in this journal,1 most head injuries were without any disturbance of consciousness.7
Although there was no documentation of the temporal relationship between onset of urinary incontinence and onset of head injury in any of these reports,2–48 one has to accept that the documentation of “excellent recovery after removal of the hematoma” in six instances of the SDH-associated urinary incontinence2 and the documentation that a patient in another report of SDH-associated urinary incontinence “regained his preoperative level of function”3 probably also signified postoperative resolution of urinary incontinence. No specific allusion was made to the outcome in the patients with incontinence documented in the other reports of SDH.4,7 It is also worth noting that, in the above reports,2–4,7 including those in which lateralizing signs were specifically not documented as being present on admission,2,3 urinary incontinence was never the sole presenting feature of SDH. In conclusion, clinicians should be aware that urinary incontinence may be a symptom of SDH even in the absence of focal neurological symptoms and signs and that its occurrence in patients with SDH who are reasonably alert should prompt a detailed documentation of its onset in relation to head injury and its resolution in relation to evacuation of SDH so as to advance our understanding of this phenomenon.