Awareness of bladder filling with divided sensory tract.

It takes a baby at least two years to learn to interpret certain sensations as indicating that the bladder needs to be emptied. When the afferent pathway from the bladder in the spino-thalamic tract has been divided, these specific sensations are no longer experienced. However, when this pathway from the bladder has been divided and the normal sensation underlying the desire to micturate has thereby been removed, it is surprising to find that many patients experience other sensations related to bladder filling and emptying; and they can learn to interpret such sensations, which intrinsically do not feel as though they are related to the desire to micturate, as an indication that the bladder needs to be emptied. The purpose of this paper is to describe and draw attention to the more common of these sensations, to report an investigation of its mechanism, and to present evidence on the pathway by which the impulses subserving it reach the central nervous system. In patients with total division of the spinal cord the occurrence of a poorly localized abdominal sensation indicating a full bladder has been reported by Balint and Benedict (1906), Riddoch (1921), Denny-Brown and Robertson (1933), Voris and Landes (1940), Donovan (1947), and Kuhn (1950); it has been reported in total lesions of the cauda equina by Kocher (1896) and Denny-Brown and Robertson (1933); and in patients with division of the lateral part of the spino-thalamic tract Nathan and Smith (1951) recorded the presence of this and other substitute sensations. The cases reported by Kuhn are of particular interest, as he made some observations on the nature of the stimulus that may give rise to the sensation in patients with proved total division of the cord; reference to his material will be made throughout this study. The abdominal sensation is not the only sensation that may act as a substitute for the normal sensation underlying the need to micturate. Occasionally, after the spino-thalamic tract has been divided, there are spontaneous tingling paraesthesiae in the lower part of the body; these may be accentuated when the bladder is full. In some patients there may be reference of sensation from below the level of the surgical lesion to the parts of the body above it; such referred sensations may originate in the bladder. As was previously mentioned by Nathan and Smith (1951), a very full bladder may cause one of the following sensations: a frontal headache, a feeling of being about to shiver or of actual shivering movements, a feeling of a need to take a deep breath; these are the sensations that accompany the reflex effects described in total cord division by Guttmann and Whitteridge (1947). There are also the sensations arising in the urethra that occur immediately before micturition; these were also briefly described by Nathan and Smith. Unless the clinician is aware of the possible existence of these substitute sensations, he may be misled by the answer to the question whether the patient knows when he needs to micturate or not. For patients having these substitute sensations may not explain spontaneously that although they know when they need to empty their bladders they have not acquired this knowledge in the usual way; it may be necessary to tell them of the existence of the normal sensation of needing to micturate and of this vague abdominal sensation before they will state that this is the sensation which they experience. Further, these sensations are useful, as they can form adequate substitutes for the normal sensation when this is absent. This vague abdominal sensation was present in I I of 20 patients who had the operation of bilateral antero-lateral cordotomy; it was also experienced by one patient with a thrombosis of the anterior spinal artery, causing extensive destruction of the afferent pathway from the bladder.