Transverse fractures of the sacrum with neurological complications have been studied in four patients illustrating the following features: diagnosis is often delayed, there are radiological difficulties in making the diagnosis, and the indications for surgery are not well defined. Specific radiographic views are recommended. All the cases presented in this report responded well to conservative management.

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PurposeCurrent methods for estimating muscle motor unit (MU) number provide values which are remarkably similar for muscles of widely differing size, probably because surface electrodes sample from similar and relatively small volumes in each muscle. We have evaluated an alternative means of estimating MU number that takes into account differences in muscle size.MethodsIntramuscular motor unit potentials (MUPs) were recorded and muscle cross-sectional area (CSA) was measured using MRI to provide a motor unit number estimate (iMUNE). This was compared to the traditional MUNE method, using compound muscle action potentials (CMAP) and surface motor unit potentials (sMUPs) recorded using surface electrodes. Data were collected from proximal and distal regions of the vastus lateralis (VL) in young and old men while test–retest reliability was evaluated with VL, tibialis anterior and biceps brachii.ResultsMUPs, sMUPs and CMAPs were highly reliable (r = 0.84–0.91). The traditional MUNE, based on surface recordings, did not differ between proximal and distal sites of the VL despite the proximal CSA being twice the distal CSA. iMUNE, however, gave values that differed between young and old and were proportional to the muscle size.ConclusionWhen evaluating the contribution that MU loss makes to muscle atrophy, such as in disease or ageing, it is important to have a method such as iMUNE, which takes into account any differences in total muscle size.

Plasma progesterone concentration was measured by a competitive protein-binding method in serial samples of jugular venous blood from 21 pregnant goats, 11 with twin and 10 with single foetuses.Progesterone levels in twin pregnancies were significantly greater than in singletons. The mean progesterone concentration (ng/ml plasma) in the twin pregnancies was greatest during the 3rd month of gestation (10\m=.\7 \ m=+-\0\m=.\4 (s.e.m.)) and in the singletons during the 4th month (7\m=.\8 \ m=+-\ 0\m=.\2 (s.e.m.)). There was a significant decrease in mean progesterone concentration in the last month of pregnancy due to a steady decline in the last 7 days before parturition.The mean progesterone concentrations at parturition in five twin and eight single pregnancies were 2\m=.\2\ m=+-\0\m=.\4and 1\m=.\5\ m=+-\0\m=.\2 (s.e.m.) ng/ml plasma respectively; there was no significant difference between these values. In cord blood from nine kids immediately after delivery the progesterone concentration was 0\m=.\9\ m=+-\0\m=.\1 ng/ml.

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