Surgical Anatomy and Physiology

ANATOMIC THINKING UNDERLYING THE INTERPRETATION OF SIGNS, SYMPTOMS, AND TREATMENT IN

TRIGEMINAL NEURALGIA

T HIS paper is not ~~~ncerned with the detailed account of the anatomy of the fifth cranial ncrvc and its associated structures; it does attempt, however.

lo correlat,e csscntial anatomic features with the signs, symptoms, and treatment of trigeminal neuralgia.

In 1773, ;lohn Fothcrgill, author of the first complete description of tri- geminii Ilcurnlgia, mrotc as follows :

From impert~eptible beginnings, a pxiu attack s some part or other of the face, or lhc side of the head: sometimes about the orljit of the eye, sometimes the ossn mcr7n~wn, some- times the temporal bonrs, iire the parts complained of. The pain ~comrs suddenly and is excruciating; it lasts for a short time perhaps :I quarter or half a minute and then goes off: it returns at irregular intervals. Eating will bring it on in some persons; talking or the least motions of the murclt~r: of the face affects others; the gentlest touch of n hand or iI handkerchief will sometimes Ijring on the pain, whilst a strong pressure on the part has no effect. It affects some who 11:~~ few or no teeth. Sornet,imes it is excited to an txtrerw dcgreo of Violence bp the slightest touch of the bed-clothes, which C:LII s~lrrely be avoitletl in turning in bed. The most ewru~iat ing pain m:ry forw out the team ant1 prod~~cy violrnt contortions of thr fare and the \~hol~~ bo~ly.

The trigeminal nerve is a misctl cranial nerve composed of a sensory and nrotor component. The modalities 01’ sensation carried through this nerve are : (a) generxl somatic affcrcnt cxttroccptive imlnllsrs of touch, pessure, pain, and

temperature from the skin OF the fact aIjt3 the ~IICOUS membrane of the oral cavity ; (b) pncral somatic sfYtrcnt ~)roprioceptive impulses from the muscles of mastication, the teeth and the palate ; (c) special visceral efferent impulses to the mllscles of mastication. 11 is important to bear in mind that although the modalities of touch, pressure, pain, and tcmpcratnre are grouped together in the peripheral divisions of’ the trigeminnl nerve, these modalities become physi- ologically separated into specific tracts when they reach the central nervous s)-stem.

The superficial attachme~~t of the trigcminal nerve is to the pans at the junction of the upper with the lower two-thirds. This fact is important in the later consideration of the espandin g tumors which may arise from the cerebel- lopontilo recess of the brain stem.

The deep connections olt this nerve-an understanding of which is im- ljerative in the interpretation of its reflex connections with other cranial nerves --are represented by groups ol’ nerve cell bodies lorated in each division of the Ikmin stem iIll< also in the: spinal Wrd. Thus (see Ii’ig. 1 ) : t,lie proprioceptivr

* l’rof~~ssor of Anatomy. Tufts College Mrdicnl and Ikntnl Schools : Consultant in Anatomy, Joseph II. Pratt JIiagnostir Hospital : Horton Dispensary.

291

nuclena for the roordinatio77 arltl co71trol of thv muscles of masticatio77 and the teeth is located in the mcsc7~cel~halon; the 177ain sensory retcption 7117clcr1s for IouCh, pressure, and proprioception is lwated in tl7e ripper part ol’ the l)ons : the nucltws of the descending tract oi' tl7c fiftl7 r7wve for the tra7ls777ission 01 pair7 and temperature irnpnlses is located in that 777cdnl la and 7nwgcs with ttrv suhstantia gclatinosa within the spinal cord. ThC thd2L7llllS, Ih(’ ll~~JOtl7i~1,27l7llS.

and the ccrchral tortes are also intcgrill parts of the trigeminal ii(‘rvc and pIa>. i7 considerahlc l)art in the judgment of 117~ IJnticnt n-hen 17,vlwrMhesia a77tl

hppcralgesia of t>he face arc present.

An csamination of Fig. 1 will snp~~ly the w77wnt~ional information of ttiv three-neurone pat hmay involved in i777pulscs tra\,cll in, 0’ Fro7n tl7e ski77 ant1 ~~LKYJ~IS mcrnhrarie to the cerebral tortes. Noie especialI\- tEli71 the nc~i770sriisor\- u71il

comprises : (a ) the end organs as the peripheral sensor’!- reception mcc~hanism. (1)) the cell bodies situatctl outside the central 77~~0~7s system withi thr tri- gerninal ganglion, and ((31 the peripheral IF tlirwtc~tl tlcridrit,es a.77d the ccntrall~ dir&cd axones of these ccl1 bodies. iTe711'071c 1 is t tirrcforc~ the trigc~minal ganglion. Neurone II is rcpresrntotl as a tadpole-shaljed st7.rlcIt1rc with the head as its 7nain sensory reception nl7clc7ls a17tl its attenuated tail as tl7c nucleus of reception for the fibers 01 the descc77din, 0 t7Ylc.t of l,hc fifth ll(‘1’VP. The cvll bodies of ncuronc II give off axis eyliridcrs which (*rosss and ;7sw71tl iis tlic tri-

gelnina lemniscus to terminate i77 tl7e tht7lat77ns which constitutes ~~(~III'OHC lJI. Tj’rom the tlialamus, thalamocorticnl fihcrs l)iwcwl to the somacst hetic arwa of the face situated in the lower third of the postccntr~al gyrus of thv vortex. 1 t7 i~ddition, the niesrncrl~l7alic nucleus is iiitlicatctl as Iwing ilt ttw Icvc~l of t t7(, superior colliculns wit17 its fihcrs passi77g orll alo71p tlitr 771~71di1~171ill~ clirisiori of

t,lic trigcniinal nerve.

Tl7c clinician mill find it 7nost nsef77l to keep i71 rni77tl the t(~r777i77atio77 of the

entering root fibers of the trigeniiiial iit’7’vc as tl7q aiarivc tvithiii the pans. b’ig. 2 shows that the “trigger” zones 77~s lrr wtivated from stiinuli i7iitiated f7tom cut,aneous (shaving), 7nucosal (lnwliiiig of tt‘c‘th ), 07' 77lllS('lllilt' (swallow- ing) surfaces. Kate especially the r70771-jif777.cnt,in~ filers which cont.riljut,e to the formation of the descending tract, ol’ the fifth I7crw ; these fihcrs are ~L71-

777yelinated or s777all rnyelinated “slow” fibers which traiisniit it771)7llscs of ljain and temperature. The fibers which ascc17d a77tl tcrminnte in the nlai77 sensor; reception nurlens convey touch and r’rol)rioc~eijtivt: iinpulses a77d ai’(s riiadc ilp of good-sized mpelinated ‘ ‘fast ” fibers. AttP7ltiOll is called to tt70 \-cntrodorsill lanlination of the peripheral divisions of t.he trigeminal 77errc wl7ich shone t hai the ophthalmic division reaches the spi77al vortl at the 2 C Intel, wliilc tilt) nias- illary a77d mandibular divisior7s 1*eacl1 levclls s7wwssively more 7wt rall;~. This anatomic point is important iii tiw~toto771\-. If, L’07’ (5ampl(~, all ;Il)St:llt, C’O7TlCill

reflex is observed, one may conrltldc~ that the \w7tral part of the spi77al t7wt 17as degenerated; if. on the other haiid. 1 trc wi*rieal 7*c4vs is iiitavt. t Iivlr (lC’~‘c’llt’l’il-

tio77 of the dorssrl part is i77ferwtl. rt is hecause the l)(/ijL a7id fejjll/evcllI4w fibers dcscancl into the 77l~dLLlliL aid tfic spinal c~jrcl whilr the 777a.ioritJ- of touch fibers ascend illto the pons ihat the proccduro of traetotorny is ;777aton7icall>

SIGNS, SYRII’T03IS, AND TREbTRlICNT IN TRIGEMI~AL NEURALGIA 293

and pII)-siologicall)- possible. This figure also trim to point out the great value to the diagnostician 01: keeping clearly in mind the activity of the cewbrcrl c0rtc.c in which highly locnlizc/l~le pcrin is perceived and the hypothalamic vegio~b \vllrrc~ rfrfctiom to ptri7c oc(‘lIr. I~‘urthemlow, the frontal lolm acting in con-

TRIGEMINAL NERVE - THREE NEURONE

AFFE RE NT PAT l-4 WAY TO CONSCIOUJNESS

294 BENJAMIK SPECTOR

junction with the hypothalamus are rwponsihlc for the emotional component and the attitudinal reactions of anxiety ant1 fear as well as certain autonomic reactions such as sweating, tachy-cadia, and lacrirnntion. The thalamus pre- sumably synthesizes all the irnp~~lscs coming ill l’lw111 the prriphcral l)~illl~llC!S of the trigeminal ncrw am1 adds a syncli*gic* aft’wtiv(l lone uot only for thti pain impulses hut also for the impulses of torIch and [)rcssure ; the thalamks thus 1)ecomes a significarit integrative area of the trigemirial nerve. Since, as alreadp pointed out, the h-pothalamns is the “c~entcr” for attitrtdinal and autonomic

ANATOMIC SITES FOR INTERRUPTION OF PATHWAYS

WHICH CARRY PAIN IMPULSES FROM THE TRIGEMINAL NERVE

Fig. 2.

SIGNS, SYMPTOMS, AND TREATMEKT IX TRIGEMINAL KEURALGIA 295

responses, the question of prefrontal lobotomy is often seriously considered as one method of dealing with the int,ractable pain of tic douloureux. This oper- ation interrupts the connections brtmeen the rerebrel cortex and the thalamus and hypothalamus (Fig. 2, no. 5). In fractional root section (Fig. 2, no. 3) the ophthalmic bundle of fibers is spared in order to protect the ipsolateral e)-c against keratitis, and injury to the motor root is also guarded against. Medul- lary tractotomy (Fig. 2, no. J), in view of the anatorny of this region, results in analgesia without anesthesia; although pain of the face is abolished, there may be slight subjective loss of touch sensation. It is also evident that, since the mandibular division is more frequently involved, the medulla must be deepl! incised to obtain optimum or rnasirnum results. Even though tractotomy is successfully performed, thcrc sometimes remains a sense of fullness or even pain in the ear as well as a persistent hot, burnin, w sensation over the anesthetic area.

Fig. 3.

This pain may be accounted for by the fact that afferent sensory impulses from the face are carried via the sympathetic fibers along the carotid vessels to the upper thoracic spinal cord segments and from the spinal cord via the spino- thalamic tracts to the cerebral cortex. Other points for the physiologic interrup- tion of pain impulses arc indicated by (Fig. 2, nos. 2 and Z), namely, alcoholic injection of peripheral branches and possible ganglionectomy.

296 BmJ.43ns SPECTOR

The differential diagnosis of tic doulollreus in relation to other structures of the brain stem is brought, out in Fig. 3. Tt sho111d 1~ clear froul the allatom>- that expanding tumors in the cercl)ellol)orltil(~ I’WCSS may producr s>-mptoms of trigemina.1 neuralgia alone or in conjunction wit II ar~ditory, \,cstibular, and cerehellar signs. T’nilateral acoustic neurom;\s, nollrinonias of the fifth nerve, or cholesteatomas may prodlIce tic doulourcl~s as the prcdorninant complaint. It would st’em. therefore, that the oral surcvon mighl find it ncccssnr~-. in I%\\ of t,lie anatomic relat,ionships of the supcrficiai at,lachmrnts of the cranial ncrvcs at the ccrcbellopontilc recess, to ha\-c the I)aticnt s~~bmittctl to audiomc~tcr ant1 vestlbular tests l~fore m;lkinc: il th~finilc~ diagnosis oi’ t rigvniinal ncurirl~ia. Obviously, where symptoms of tic doulol~rc~llx csist in associatioll with lle:lring deficit,, vestihular changes, and in~ool~tli~l;ltio~~ ot’ ~tIovcnicnts, tticl cliagz~osis 01’ true trigeminal neuralgia must. 1~1 lir~l(l ill ~llN!~~ilI~~('.

FLOOR OF FOURTH VENTRICLE

REFLEX CONNECTIONS OF TRIGEMINAL

NERVE WITH OTHER CRANIAL NERVES

The floor of the fourth ventricle merits careful consideration by the clini- rian, for here is afforded an arrangement of cranial nerves which easily accounts for the many reflexes observed in tic douloureux. Fig. 4 shows the fourth

\entricle bounded t)y the threr ccrcl~ellar peduncles. There are transvcrsc white fibers which woss the qa;r- matter called the strine medullares, which in I III’IL divide tlw floor int,o a lower mcdullary and an upper pontine division. 1 II t.hr nrc~d111l;rry part arc 1ocattLcI the nllclci of the ac+oustic, glossopharyngcal. iI(‘~(‘SSO~~\~, and h~poglossal 1lc’I’V~‘S. In tlw pontinc part are located the nuclei of t lit triq~tninal, al)duc~ms, ad facial ncrvcs. It is clear now that if lhc tri- zclrlinill stvw)iy wwptioii nnc~lc~w wcrc lwml~~rdcd 1)~ painful impnlscs from t hc pwiphcry. throlqh collateral filjcrs or tlirougli the short nenroncs whicli make up tlw reticular sal~staiice of the Roar of the fourth vcntriclc, the signs and spptoms noted in Fig. 4 may result, namely: (a) mout,h fixed in open Iwsition due to excessive stimnlat,ion of the motor nucleus of the tripeminal nerve: ih) reflex squeezing of eplids , grimaces, I)lepharosl,asm, spasm of t hcl TaGal muscles froni irritation of the facial nwleus ; (c) increased salivation fw~i overstimulatior1 oi’ the facial and glossopharyngcal nuclei ; cd) excessi\e sweat- ing, l~radycaI~(lia, or tachycardia Cram overflow of stimuli to the V~QUS IIUPIPUS :

(c) spasmodic turning of the head From impulses rcnvhin, 0 the arcessor~ llllclcns

and the nuclei of the cervical spinal nerves. The functional anatomic mechanisms presented in this discnssion of the

trigeminal n(‘rve ma\- well reaffirm tllc opinion of thoughtful clinicians that klIlatOlll)- k 110 hll~Cr n ~at~llOgllc Of IlilJllCS hut a JllPthOd of WlderStaJl(~bl~ :(JJtl

interpretation. References

Adson, ;\\. W.: The Radical Treatment of Trifacixl Nellralgia, PIill. 14: lo~i~~)-ln79. lW2.

Collectetl Papers of Afag

(‘uslling, 1-I. : Tht? Major. ‘+&Gin:+1 Seuralgiax and Their Swgical Treatment Based on Experiences With 332 Gasserian Operations, Am. .T. M. SC. 160: 157-184, lQ20.

I)avis, r,.. an{1 TIaven, JI. A.: Surgical L4natonlp of Sensory Root of Trigeminal N~YL-F, i\wh. Neural. & Psyehiat. 29: l-18, 1933.

l.‘otIlwgill, .J. : On a Painful Affection of the Face, Medical Observation xnd Inquiries 5: l‘,O 177.2 --’ , .. ”

bhzirr, (‘. II., and Whitehead, E.: The Morpl~ology 48: 458-475. 1925.

of the Gnsserinn Ganglion, BliliIl

F‘1,:lzicar. C. H.: Pain Phenomena of thr Face, Their Origin aud Treatment With Spevixl Reference to Trigeminxl iY-euralgix, Au]. J. hf. Ro. 169: 469.476, 1925.

G~~lmd. hr. w’. : Afferent Impulses of the Trigeminal Serve, Arch. Seurol. & Psycltiat. 9: RO(i-1’38 192:: **, .

lIarl,ison, I”., and eorbin, Ii. B.: Oscillographic Studies on the spinal Tract of the ]Piftll Cranial P;erve, .T. Keurophysiol. 5: 465.4S2, 1942.

.I ro~fils c: .1 and Poppen, J. L.: Trigeminal Neuralgia. Expwienecs With, ’ Emploved in 468 Patients Iluring the Past, 10 Years, Surg.,

and Treatment

:w4oi, 1935. Ggnec. 6; Obst. 61:

Otennsek? F. .T.‘: Prefrontal Lobotomy for the Relief of Intractable Pain, Bull. Johns Hopkins Hosp. 83: 229-236, 1948.

I:nason, S. W.: Non-medullated Serve Fibers in the Spinal Serves, Am. J. Anat. 12: 67.87, 191 1.

lievilla, A. G.: Tic 1)ouloureux ant1 Its Belationshiy to Tumors of the Posterior Fossa, .J. Seurosurcr. 4: 2X-239. 1947.

Rrvilla, A. G.: l%fferential Diagnosis of Tumors at the Cerebellopontile Recess, Bull. Johns Hopkins Hosp. 83: 187-212, 1948.

Sjiiql-ist, 0.: The Conduction of Pain in the Fifth Scrre and Its Bearing on the Treatment OC Trigeminal Neuralgia, Yale J. Biol. & Med. 11: 5Q3-600, 1939.

St,opford, J. 8.: The Function of the Spinal Nucleus of the Trigeminal Xerve, J. Anat. 59: 120-128, 1925.

V’alker, i\. B.: Anatomy, Physiology and Surgical Considerations of the Spinal Tract of 111c Trigeminal Xerre, J. l?reurophvsiol. 2: 234-248, 19%.

XVindlr, IV. F.: Nowbifurcating Serve Flhers of the Trlgeminal Nerve, J. Comp. Neurol. 40: 29-240, 1926.