Anatomy of the lumbar spine

The macroscopic courses of the posterior primary rami in the lumbar spine are described and illustrated from fresh cadaver dissections.

[Results of selective posterior radiculetomy at the lumbar and cervical level]

At the light of authors' present experience, radicletomy appears as an excellent antalgic operative procedure in the case of roots with high functional risk (brachial plexus and lumbar plexus). In the absence of any motor deficiency or ataxia, it appears that radicletomy is of help in the cure of severe hypertonies of the extremities (sequelae of cerebral stem contusions). Conversely, in the spastic sequelae of hemi- or paraparesias, lumbar-sacral posterior selective radicotomy is a sure procedure that procures results nearly super-imposable to radicletomy with an appreciable gain in time. At last, for what concerns the motor involvements of the upper extremity ending in spasticity, selective radicletomy recovers its rights and has to be preferred to S.P.R. The indications may be summarized as follows: -- At the level of the lower extremities: in the case of paraparetic sequelae or of sequelae due to spastic paraplegia, a S.P.R. has to be performed; for what concerns antalgic surgery, in the absence of motor deficiency, the best indication is radicletomy. -- At the level of the upper extremities: in the case of dystonic sequeale of the cerebral stem, spastic pain bound with hemiplegia or with carcinoma etc. (herpes zoster..), radicletomy constitutes the ideal surgical procedure.

Spinal and supraspinal components of the reflex discharges into lumbar and thoracic white rami

1. In chloralose anaesthetized cats reflex discharges in thoracic and lumbar white rami were elicited by single shock stimulation of intercostal, spinal and hind limb nerves.2. In animals with an intact neuraxis single stimuli of sufficient strength usually elicited a white rami mass discharge having two distinct components. Following spinal transection only the late reflex component disappeared.3. The early (spinal) reflex component had its largest amplitude if the afferent volley entered the spinal cord at the same or an adjacent segment of the white ramus under observation, whereas the size of the late (supraspinal) component was rather independent of the segmental level of the afferent input.4. It was concluded that somatic afferent volleys have a twofold action on the sympathetic nervous system: a more generalized action via the supraspinal sympathetic reflex centres and a more circumscribed action on the preganglionic neurones at the segmental level.

Calf denervation in the treatment of intermittent claudication

Seventy per cent of 44 selected claudicants were improved following calf denervation.

We feel that this simple operation has a place in the treatment of many claudicants, especially those in whom direct arterial surgery is not feasible.

Presynaptic inhibition of the monosynaptic reflex by vibration

In cats, the monosynaptic reflex (MSR) elicited from L7 or S1 dorsal roots, or from the tibial nerve (H reflex) was suppressed by vibration at 50-500 c/s of the hind limb with innervation intact. The MSR was not suppressed by selective vibration of cutaneous receptors, and suppression was still observed after the hind limb was skinned. In contrast, the phenomenon disappeared when all muscle nerves were crushed. SUPPRESSION OF THE MSR BY VIBRATION WAS SHOWN TO BE MEDIATED BY PRESYNAPTIC INHIBITION BY THE FOLLOWING METHODS: correlation with onset of the dorsal root potential (DRP) evoked by vibration, and abolition of both DRP and reflex suppression by picrotoxin; demonstration of primary afferent depolarization and normal excitability of motoneurones to direct stimulation. Reasons are given for deducing that the muscle afferent fibres responsible for the presynaptic inhibition induced by vibration are group Ia rather than groups Ib or II, or afferent fibres from Pacinian corpuscles.