Responses of Purkinje cells of cerebellar vermis to sinusoidal rotation of neck

1. The response of Purkinje (P) cells located in the vermal cortex of the cerebellar anterior lobe to sinusoidal rotation of the neck was investigated in precollicular decerebrate cats. The head of the animal was fixed in a sterotaxic frame while the spinous process of the second cervical vertebra was held by a clamp rigidly fixed to the tilting table. It was then possible to elicit a selective neck input by rotating the neck and the body simultaneously along the longitudinal axis of the animal while maintaining the head in horizontal position. 2. Among the 95 P-cells tested for neck stimulation, 35 units showed a mossy fiber (MF) or a climbing fiber (CF) response to sinusoidal rotation of the axis vertebra at the frequency of 0.026 Hz and at the peak amplitude of displacement of 5--10 degrees. The response consisted in a periodic modulation of the discharge frequency during sinusoidal rotation of the neck. Most of these units were excited during side-down rotation of the neck, but were inhibited during side-up rotation. 3. The threshold amplitude of neck rotation responsible for the MF-induced responses varied in different units from 1 to 3 degrees at the frequency of 0.026 Hz. The sensitivity of the units, expressed in percentage change of the average firing rate per degree of displacement, either did not change or very slightly decreased as a result of increasing amplitude of stimulation from 1--3 degrees to 10--15 degrees at the frequency of 0.026 Hz or by increasing frequency of neck rotation from 0.015 to 0.15 Hz at the amplitude of neck displacement of 5--10 degrees. 4. Changes in amplitude or frequency of stimulation at the parameters reported above did not greatly modify the phase of the unit responses relative to the side-down position of the neck. These findings indicate that the MF and CF responses of P-cells to sinusoidal rotation of the neck depended on changes in neck position and not on changes in velocity of neck rotation. 5. The observation that the majority of responding P-cells located in the vermal cortex of the cerebellar anterior lobe increased their firing rate during side-down rotation of the neck is discussed in relation to the results of stimulation and lesion experiments, indicating that postural changes can be elicited either during asymmetric stimulation of neck receptors or by unilateral interruption of the neck afferents.

Cervico-occipital pain and its surgical treatment: the myth of the bony millstones

The proposal was made in 1949 that occipital neuritis/neuralgia was frequently of traumatic origin. The hypothesis was advanced that the C2 sensory root lay unprotected between the lateral masses of the atlas and axis and was vulnerable to squeezing on extreme extension or rotation of the head. This conjecture converted a hitherto banal neurologic affliction into the sequela of a banal trauma. Hence, it has been exploited in the diagnosis and treatment of whiplash injuries as well as for headaches of unknown origin. Evidence is presented that the original anatomic proposition was erroneous and that the C2 root is not exposed and is not vulnerable. Indeed, a survey of the "worst" traumatic and pathologic disruptions of the craniospinal junction shows that although they would be expected to injure the C2 root, in fact, they do not. The theory as well as the operations based upon it, particularly intradural section of the C2 root, should be abandoned.

[Pathomechanism of pain in vertebral column diseases]

The pathological mechanism of pain in vertebral column diseases is discussed in accordance with the theory of Melzack and Wall taking into account both systems of pain sensation control at the spinal level and reticular formation level. The action of pain mediators is discussed as well. The main pathogenetic factors are: compression, stretching and ischaemia. Other factors, functioning particularly at the cervical spine level are, most frequently, developmental anomalies in the occipito-cervical area and faulty posture assumed during occupational work, as well as injuries which may be remote in time and forgotten. Elimination of pain perception may be obtained with surgical methods or by physicochemical means blocking the conduction of pain impulses.

[Cervical-nystagmus as related to vertebral receptors]

Two patients with absent peripheral labyrinthine function are reported, in whome cervical nystagmus could be demonstrated. Return of labyrinthine function with simultaneous disappearance of the cervical nystagmus in one of the patients demonstrates existence of receptors in the upper three vertebral joints and their potential influence on the vestibular system. Pathogenetic as well as diagnostic functions of the sensory afferent systems of the upper cervical region are discussed.

Innervation both of peri-orbital structures and of the heart by the cervical sympathetic nerves in mouse, rat, guinea-pig, rabbit and cat

1 In anaesthetized rats electrical stimulation of the intact cervical sympathetic nerve produced frequency-dependent lower eyelid contractions and tachycardia. 2 The tachycardia was caused by excitation of efferent fibres since it was equally evident in the pithed rat preparation, and the right nerve was more effective than the left. By contrast, no differences were seen between the responses to right and left vagal stimulation in either rats or rabbits. 3 Guanethidine inhibited both cardiac and eyelid responses, propranolol only the former and phentolamine only the latter, therby revealing the adrenergic nature of the nerves. Hexamethonium caused partial inhibition and the block was intensified by atropine. 4 The inferior eyelid of mice, guinea-pigs and rabbits as well as the nictitating membrane of rabbits and cats were contracted by cervical sympathetic nerve stimulation. In these species too, tachycardia occurred; this was more pronounced with the right than the left sympathetic nerve. The order of cardiac responsiveness was mouse greater than rat greater than guinea-pig greater than rabbit greater than cat. 5 In guinea-pigs histamine-induced bronchoconstriction was reduced by cervical sympathetic nerve stimulation. 6 That discrete cardiac pathways exist in the cervical sympathetic nerves is suggested by the reproducibility of the effects within any one species. The accessibility of the nerves greatly simplifies the examination of drugs in vivo on two different structures innervated by the sympathetic nervous system.