Effectiveness of earplugs in high-intensity impulse noise.

The efficiency of different types of earplugs was assessed by means of Békésy audiometry following the exposure of 42 human subjects to weapon impulses. The peak pressure of the impulses ranged from 2.3-27.8 kPa (from 161 to 183-dB peak SPL) and the A-weighted equivalent level (over 8 h) of each exposure ranged from 100-114 dB. All subjects wore earplugs fitted by an experienced individual. The devices tested included one brand of conventional foam earplugs and a number of different models of perforated earplugs, one type of which had been previously shown to provide nonlinear attenuation. Perforated earplugs were tested because they provide better speech communication than conventional passive earplugs, and in the nonlinear case also afford attenuation that increases with the peak pressure of the impulses. The temporary threshold shifts (TTSs) observed in these experiments were very small and indicated no significant hazard for hearing. Well-fitted perforated earplugs seem to be able to protect the ear from infrequent exposures to the high-level impulses produced by small and large weapons while allowing good speech communication, and without impairing the operational capacity of soldiers who must remain aware of their acoustic environment.

Unilateral swelling of the lower abdominal wall. Unusual clinical manifestation of an upper lumbar disc herniation.

Circumscribed unilateral paralysis of abdominal muscles is a rare clinical feature and has previously been described in diabetic neuropathies and traumatic or non-traumatic compressive neuropathies. The paper describes a case presenting with transversus abdominis muscle paralysis and burning paraesthesia in the anterolateral aspect of the thigh caused by a lateral L2-L3 disc herniation. Abdominal echography and the EMG investigation led to the suspicion of a disc prolapse which was eventually verified by myelography completed with a CT scan. Surgery confirmed L2 root compression by a large calcified herniation in the intervertebral foramen L2-L3. The anatomical principles are recalled to explain the clinical manifestations.

Primary brain stem haemorrhages: clinico-radiological considerations on five cases observed.

Five patients with primary brain stem haemorrhage are reported, of whom four survived. One died from complications involving other organs. The diagnosis was made by computerized tomography which also allowed the temporal evolution of the lesion to be followed. The importance of haemorrhagic lesions in brain stem vascular pathology with regard to ischaemic lesions is re-evaluated.