J7ournal ofNeurology, Neurosurgery, and Psychiatry 1996;60:399-402

Early diagnosis and stage classification of vocalcord abductor paralysis in patients with multiplesystem atrophy

Eiji Isozaki, Akira Naito, Satoshi Horiguchi, Rie Kawamura, Tetsuro Hayashida,Hitoshi Tanabe

Department ofNeurologyE IsozakiH TanabeDepartment ofNeurotology, TokyoMetropolitanNeurological Hospital,Tokyo, JapanA NaitoS HoriguchiR KawamuraT HayashidaCorrespondence to:Dr Eiji Isozaki, Departmentof Neurology, TokyoMetropolitan NeurologicalHospital, 2-6-1, Musashidai,Fuchu, Tokyo 183, Japan.Received 9 June 1995and in final revised form8 December 1995Accepted 20 December 1995

AbstractObjectives-Vocal cord abductor paraly-sis (VCAP) is a life threatening complica-tion which may cause nocturnal suddendeath in patients with multiple systematrophy. However, the early diagnosis ofVCAP is often difficult to make on routinelaryngoscopy performed during wakeful-ness, as stridor, which is the sole symp-tom of VCAP in the early stage, developsonly during sleep. The aim was to investi-gate laryngeal dysfunction in patientswith multiple system atrophy while awakeand asleep.Methods-Seven patients with multiplesystem atrophy with nocturnal stridorand five control patients were studied.Vocal cord movement was analysed bylaryngoscopy while the patients were

awake and also during sleep induced byintravenous diazepam.Results-When awake, for the seven

patients with multiple system atrophynormal movement of the vocal cordsoccurred in three, mild abduction restric-tion in three, and paradoxical movementin one. When asleep, however, all showedobvious paradoxical movement with highpitched inspiratory stridor. In controls,there were no differences in the vocalcord movement between wakefulness andsleep. From these findings, VCAP couldbe divided into four stages: stage 0 (nor-mal) with normal vocal cord movementduring both wakefulness and sleep, stage1 (mild VCAP) with normal movementduring wakefulness and paradoxicalmovement during sleep, stage 2 (moder-ately severe VCAP) with abductionrestriction during wakefulness and para-doxical movement during sleep, and stage3 (severe VCAP) with an almost midlineposition for the vocal cords during bothwakefulness and sleep.

Conclusions-Laryngoscopy during sleepcan disclose subclinical VCAP, making an

early diagnosis of VCAP in patients withmultiple system atrophy. Stage 2 ofVCAPseems to be a suitable stage for tra-cheostomy in patients with multiple sys-tem atrophy.

(7 Neurol Neurosurg Psychiatry 1996;60:399-402)

Keywords: multiple system atrophy; vocal cord abductorparalysis; sleep; stridor

Patients with multiple system atrophy present-ing with vocal cord abductor paralysis (VCAP)can suddenly die during the night due to chok-ing.'-3 Many previous investigators haveemphasised that VCAP often requires emer-

gency tracheostomy.8 However, we considerthat sudden death may occur due to delay inthe diagnosis of VCAP or hesitation in per-forming tracheostomy as many patients withmultiple system atrophy and VCAP do notdevelop either speech disturbances5 or severe

swallowing disturbance.7 There are two seri-ous problems in the management of multiplesystem atrophy. How is it possible to make an

early and correct diagnosis of VCAP? Whenshould tracheostomy be performed after thediagnosis of VCAP? To clarify these situa-tions, we analysed vocal cord movement bylaryngoscopy during wakefulness and also dur-ing sleep induced by diazepam. We have alsomade the first attempt to classify VCAP by thestage of severity and discuss the timing of tra-cheostomy.

Materials and methodsSeven patients with multiple system atrophywith nocturnal stridor and five control patientswere studied (table 1). Three patients withmultiple system atrophy (2, 3, and 5) hadalready been analysed by laryngeal EMG.9

Table 1 Neurologicalfeatures ofpatients with multiple system atrophy with vocal cord abductor paralysis

Neurological signsDuration

Patients Agelsex (y) C E P BD OH Dysphagia

1 49/F 7 + + + + + Mild2 63/M 8 + + + + + Mild3 70/F 2 + + + + - Mild4 62/M 4 + - - + + Mild5 61/M 6 + + + + + Mild6 68/F 2 + + + + + Tubefeeding7 64/M 6 + + + + + Tube feeding

C = Cerebellar signs; E = extrapayramidal signs; P = pyramidal signs; BD = bladder disturbance; OH = orthostatic hypotension.

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Table 2 Laryngologicalfindings ofpatients with multiple system atrophy and vocal cord abductor paralysis (VCAP)

Stridor ABGA (mm Hg)Onset of VGAP-

Patients VCAP Disability Awake Sleep pH Pco2 Po' penrod Laryngoscopy

1 7 Moderate - + 7 40 42 83 9 months Stage 12 8 Moderate - ++ 7-33 42 74 5 months* Stage 13 3 Mild - + 7-34 44 72 > I y Stage 24 4 Moderate - ++ 7-37 45 58 12 days Stage 25 5 Moderate - ++ 7-38 47 76 > 1-5 y Stage 26 2 Mild - + 7-44 47 64 10 months Stage 17 6 Moderate + ++ 7-34 55 68 2 days Stage 3

*Tracheostomised due to aspiration pneumonia.ABGA = Arterial blood gas analysis during wakefulness; VCAP-period = period from diagnosis of VCAP to tracheostomy, ifperformed.

The controls included three patients with non-neurological disorders as normal controls andtwo with amyotrophic lateral sclerosis withbulbar symptoms as disease controls. Table 2shows the disability score and the VCAPrelated findings, including arterial blood gasanalysis, during wakefulness around the timeof laryngoscopy. Disability of the patients was,

Exp.Inplnsp _ _ _

Figure 1 Vocal cord movement in a normal subject. The vocal cords abduct on inspirationand slightly adduct on expiration. There are no significant changes between wakefulnessand sleep.

Figure 2 Mild vocal cord abductor paralysis (stage 1) in multiple system atrophy (patient6). Vocal cord movement is normal while awake, but paradoxical during sleep: the vocalcords adduct on inspiration rather than on expiration.

for convenience, evaluated as follows: "mild"means ambulatory with or without a cane,"moderate" means ambulatory with a walkeror wheelchair, and "severe" means bedridden.Vocal cord movement was analysed by laryn-goscopy while the patients were awake andduring sleep induced by intravenous treatmentwith 5 to 10 mg diazepam. Pictures were mon-itored on a video display unit and recorded ona videocassette. An intratracheal tube wasalways available in case of emergency.

ResultsFigure 1 shows the vocal cord movement in anormal subject, with no significant differencebetween wakefulness and sleep: the vocalcords abduct fully on inspiration and adductslightly on expiration. A similar pattern wasseen in the other four controls. In the patientswith multiple system atrophy, three differentpatterns were found. In patient 6 (fig 2),although the vocal cords functioned normallyduring wakefulness, they adducted on inspira-tion and abducted on expiration during sleep.Such a nocturnal paradoxical movement wasalso seen in patients 1 and 2. Arterial bloodgas analysis while awake in this group showedmild to moderate hypoxaemia (table 2). Inpatient 3 (fig 3), laryngoscopy showed mildabduction restriction of the vocal cords whileawake and paramedian fixation with paradoxi-cal movement during sleep. A similar patternoccurred in patients 4 and 5. The pattern wasmore severe in patient 4. The arterial bloodgas analysis during wakefulness in this groupshowed moderately severe hypoxaemia with orwithout hypercapnia. In patient 7 (fig 4), thevocal cords took almost a paramedian to mid-line position, resulting in a slit-like glottisaperture. Moreover, the small aperturebecame narrower during sleep, showing analmost midline position of the vocal cords inassociation with high pitched and heavy inspi-ratory stridor. In this patient, intratrachealintubation was carried out immediately afterthe finding because of the danger of chokingto death. The arterial blood gas analysisjust before the intubation showed pH 7*34,Pco2 55 mm Hg, Po2 68 mm Hg. Table 1and 2 indicate that there were no relationsbetween VCAP and duration of illness,disability score or other neurological find-ings apart from bladder disturbance. Highpitched inspiratory stridor was audible duringsleep in all the patients and while awake inpatient 7.

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Early diagnosis and stage classification of vocal cord abductor paralysis in patients with multiple system atrophy

U nsp. "'! ,IExp.I

Figure 3 Moderately severe vocal cord abductor paralysis (stage 2) in multiple systematrophy (patient 3). Vocal cords show mild abduction restriction during wakefulness andparamedian fixation with paradoxical movement during sleep.

Figure 4 Pronounced vocal cord abductor paralysis (stage 3) in multiple system atrophy(patient 7). Vocal cords take an almost midline position while awake and asleep.Intratracheal intubation was done immediately after this finding.

DiscussionADVANTAGES OF LARYNGOSCOPY DURING SLEEPThe present study showed three advantagesof laryngoscopy during sleep (sleep-laryngoscopy). Firstly, it permits an early diag-nosis of VCAP because the vocal cords inpatients with multiple system atrophy andVCAP showed dramatic paradoxical move-ment only during sleep, although their move-ment when awake was normal. Consideringthat the routine laryngoscopic examination isusually performed during wakefulness in day-time, sleep-laryngoscopy is definitely requiredfor those patients with multiple system atro-phy who snore heavily, to disclose subclinicalVCAP.

Secondly, it is sometimes difficult to differ-entiate true abduction restriction of the vocalcords due to VCAP from seeming abductionrestriction due to some aspiration in patients

with multiple system atrophy. The vocal cordsin the patients with dysphagia have a tendencyto reflective adduction based on a laryngealprotective mechanism against aspiration.'0Hypotonus of the laryngeal muscles duringsleep seems to reduce such an excessive reflec-tive adduction.

Thirdly, sleep-laryngoscopy is able to definethe sound source for snoring or stridor."1 Thedifference is clinically important as non-lifethreatening ordinary snoring, which appears inhealthy normal subjects, is usually derivedfrom the pharyx in the area between theepiglottis and the choanae,'2 whereas lifethreatening inspiratory stridor in patientswith multiple system atrophy is from thevocal cords of the larynx. Therefore, sleep-laryngoscopy is useful to identify dangerous"snoring"-namely, stridor.We speculate that VCAP becomes dramati-

cally apparent during sleep because laryngealmuscle tone in patients with multiple systematrophy with VCAP is prominently adductionas the sole abductor-the posterior cricoary-tenoid muscle-is selectively involved in neu-rogenic atrophy.' 13-1' Also, all the laryngealmuscles lose their activities when asleep.'6'18As a result, the adduction predominant larynxcan be easily pulled inwards and downwardsand then collapsed by intratracheal negativepressure on inspiration. Such an aerodynamicinbalance between the laryngeal muscle toneand airflow pressure seems to cause sleepinduced paradoxical movement of the vocalcords. Moreover, our laryngeal EMG studiesof patients 2, 3, and 5 performed previouslyshowed that the inspiratory activity of theadductor (the thyroarytenoid muscle) and thefade out phenomenon of the abductor mightalso participate in the mechanism of sleepinduced exacerbation.9 We have dividedVCAP into two types, the paralytic type inmultiple system atrophy and the non-paralytictype in Parkinson's disease.19 The second wasthought to be caused by the persistent overac-tivity of the intrinsic laryngeal muscles, possi-bly derived from supranuclear involvement.Because some patients with multiple systematrophy develop predominant extrapyramidalsigns, VCAP in such patients might be causedby a supranuclear mechanism (the non-paralytic type ofVCAP) in addition to the par-alytic type.

STAGE CLASSIFICATION OF VCAPWe divided VCAP into four stages (table 3)according to the laryngoscopic findings. Then,referring to the clinical findings and to ourprevious chronological study,20 we hypothe-

Table 3 Stage classification of vocal cord abductorparalysis on laryngoscopy

Vocal cord movement

Stage Awake Asleep

Stage 0 (normal) Normal UnchangedStage 1 (mild) Normal ParadoxicalStage 2 (moderate) Abduction restriction ParadoxicalStage 3 (severe) Midline Midline

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sised thatVCAP might deteriorate from stage 1to stage 3 through stage 2. However, theremay be some exceptions in this order, such as a"skip" deterioration from stage 0 to stage 2 orfrom stage 1 to stage 3, as our previouschronological study was limited to one patientwho was examined only while awake. Also, thestage of sleep depth may be different amongthe individual patients under drug inducedsleep and it is possible that the severity ofVCAP may depend on this the depth of sleep,as Kakitsuba et all' have already pointed out.To confirm the stage classification morepatients need to be studied chronologically,with concomitant EMG recordings.The perplexing problem is when trache-

ostomy should be performed after the diagnosisof VCAP. In stage 1, there seems to be timeenough before tracheostomy; nine months inpatient 1 and 10 months in patient 6 (table 2).Tracheostomy in stage 3 is obviously too late.Therefore, stage 2 seems to be the suitablestage for tracheostomy. Table 2 indicates twoclinical findings that are helpful in identifyingthis stage-namely, when the inspiratory stri-dor becomes audible, not only during sleepbut also during wakefulness and when thearterial bicarbonate concentration rises whileawake. However, the present study showedthat arterial blood gas analysis during wakeful-ness is not always useful for evaluating theseverity of VCAP, as most critical respiratoryfailure appears during sleep. It should also beborne in mind that severe VCAP requiringtracheostomy can develop even in the earlystage of the disease when patients are stillcapable of walking, eating, and drinking.

In the past, tracheostomy was the onlytreatment for VCAP in patients with multiplesystem atrophy. Some tracheostomisedpatients could speak by setting a speech valvein a cuffless tracheal cannula.20 At present,however, there are four main procedures otherthan a tracheostomy for the treatment oflaryngeal airway stenosis due to VCAP-namely, arytenoidectomy, cordectomy, cordlateralisation, and laryngeal re-innervation.2' 22

For patients with multiple system atrophy,however, there has so far been only one reporton the management of vocal cord lateralisationwithout the need for a permanent tra-cheostomy.2" The reason why these airwayrelieving procedures have not been applied topatients with multiple system atrophy mightbe related to the fact that multiple system atro-phy is a progressive neurodegenerative disor-der associated with severe aspiration sooner orlater. Nevertheless, we think that procedures

for airway restoration should be attempted inmore patients with multiple system atrophypresenting with VCAP.

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