J. Neurosurg. / Volume 31 / August, 1969

The Postural Effect of Lesions of the Vestibular Nuclei: A Note on Species Differences Among Primates

EDWARD TARLOV, M.D.* Surgical Neurology Branch, National Institute of Neurological Diseases and Stroke, National Institutes of Health, Public Health Service, Department of Health, Education and Welfare, Bethesda, Maryland

HE pathology of human spasmodic and, in some cases, the Fink-Heimer silver torticollis 1,12,14,15,~3 has not been con- stains for degenerated axons were used on T vincingly demonstrated and therefore adjacent series. The sections stained for cells the recent papers 13,16 on abnormalities of head were projected onto Kodak photomechanical posture resulting from experimental lesions T paper and photographed. Nuclear bounda- in the brain stem have evoked considerable ries and destruction of tissue by the lesion interest. Lately I have had an opportunity were drawn directly onto these photographs, during the course of a study of the primate and reconstructions of the brain stem and central vestibular connections 24 to observe the extent of the lesion were made from 10 Macaques, a baboon, and a chimpanzee tracings of these photographs. A detailed de- with experimental lesions of the vestibular scription of each of these lesions, the extent nuclei. Lesions of similar extent produced of damage, however slight, to surrounding strikingly different postural effects in the regions, and the rostral projections of degen- species examined. The data indicate that le- erated fibers is given elsewhereY 4 sions in the central nervous system that are The terminology used to describe the ves- responsible for abnormalities of posture in tibular nuclei is that of Brodal and monkeys may have quite different effects on PompeianoY In addition to the four classical the posture of the higher primates. vestibular nuclei (the superior vestibular nu- cleus of von Bechterew, the medial vestibu- Materials and Methods lar nucleus of Schwalbe, the lateral vestibu- Ten immature and adult Rhesus Ma- lar nucleus of Deiters, and the spinal vestib- caques (Macaca mulatta), a large male ba- ular nucleus), two other regions are indi- boon (Theropithecus gelada), and an imma- cated in Figs. 1 to 4. These are the intersti- ture female chimpanzee (Pan troglodytes E. tial nucleus of the vestibular nerve, whose P. Walker) were studied. None of the ani- cells lie interspersed among the fibers of the mals had been previously used in any other vestibular nerve, and the area x, a small studies or operations. group of cells lying between the caudal tip of Lesions in the right lateral floor of the the spinal vestibular nucleus and the lateral fourth ventricle were placed with a fine cuneate nucleus. The abbreviations for the curved glass suction pipet under direct vi- terminology are given below. sion, after elevation of the cerebellar vermis A.pt. area postrema through a suboccipital craniectomy. The ani- Am. nucleus ambiguus mals were deeply anesthetized and sacrificed B.cj. brachium conjunctivum by perfusion following postoperative survival C.r. restiform body times of between 6 and 16 days. Longer sur- Cu.L. lateral cuneate nucleus vivals interfered with optimal selective silver Cu.m. medial cuneate nucleus staining of degenerated axons. D.mo.X dorsal motor nucleus of the vagus After fixation, frozen sections were cut at F.L.m. medial longitudinal fasciculus 25 to 30 7 in frontal, sagittal, or horizontal G. gracile nucleus planes. Serial sections every 450 to 500 p. G.L. lateral geniculate body N.po. pontine nuclei were stained with cresyl violet or luxol fast N.t.s. nucleus of the tractus solitarius blue and cresyl violet. The Nauta-Gygax N.Vme. mesencephalic nucleus of the tri- Received for publication July 26, 1968. geminal nerve * Present address: Neurosurgical Service, Massa- N.Vmo. motor nucleus of the trigeminal chusetts General Hospital, Boston, Massachusetts. nerve 187 188 Edward Tarlov

Fro. 1. Sections showing extent of lesions involving vestibular complex. Comparable lesions that pro- duced severe postural abnormality in Macaques were associated with only slight postural disturbance in the baboon and even less in the chimpanzee. A. Macaque V-2. Frontal sections progressing from caudal to rostral. Lesion involved right spinal, medial, lateral, and superior vestibular nuclei and injured superior cerebellar peduncle and posterior column nuclei. Animal had severe cephalic and trunk torsion (see Fig. 5 left), B. Macaque V-3. Sagittal section; left side is rostral. Lesion involved medial and spinal vestibular nuclei. The animal's marked postural abnormality was similar to that of Macaque V-2. C. Baboon V-1-67. Sagittal section; left side is rostral. Lesion involved right superior, medial, lateral, and spinal vestibular nuclei. Animal had only slight postural disturbance, with ipsilateral in- clination of its head. D. Chimpanzee C-1-67. Sagittal section; right side is rostral. Lesion of superior, medial, lateral, and spinal vestibular nuclei, also damaged superior cerebellar peduncle. The animal demonstrated only very slight and transient postural disorder which lasted 3 days (see Fig. 5 right).

N.Vs. principal sensory nucleus of the Ve.L. lateral vestibular nucleus (Deiters) trigeminal nerve Ve.m. medial vestibular nucleus Ne.IV trochlear nerve (Schwalbe) Ne.VII facial nerve Ve.s. superior vestibular nucleus O.i. inferior olive (Bechterew) Ru. red nucleus Ve.sp. spinal vestibular nucleus S.n. substantia nigra Ve.in. interstitial nucleus of the vestibular T.O. optic tract nerve