Acute Spinal-Cord Lesions from Diving Epidemiological and

Refer to: Kewalramani LS, Kraus JF: Acute spinal-cord lesionsfrom diving-Epidemiological and clinical features. WestJ Med 126:353-361, May 1977

Acute Spinal-Cord Lesions fromDiving Epidemiological andClinical FeaturesL. S. KEWALRAMANI, MBBS, MSOrth and JESS F. KRAUS, MPH, PhD, Davis

The aquatic activity that produces the greatest number of spinal-cord lesionsis diving. Persons in the general population at greatest risk are males aged 15to 19 years. Of the cases identified, 45 percent resulted from diving into a riveror stream, 27 percent into swimming pools and 28 percent into lakes, reservoirsor the ocean. Distribution by age differed for the major groups of bodies ofwater. The incidence of spinal-cord injuries was related to season (spring-sum-mer) and day of the week (weekends). The incidence of injuries was highest inthose county areas with the least opportunity for exposure to swimming poolsor rivers. Of the injured persons, 60 percent were tetraplegic at hospital ad-mission. The most frequent radiologic finding was wedge fracture. This find-ing, in the absence of objective evidence that most divers struck the bottom ofthe water reservoir or a hard object, suggests that hyperventroflexion was themechanism responsible for injury in most of the cases. Physicians and othersshould be aware of strategy options for preventing or reducing such injuries.

AMONG the most popular leisure-time activities ofAmericans are aquatic sports including swimming,diving, scuba diving, waterskiing and surfing. Theinjuries that may result range from trivial ones tospinal-cord lesions and to death from drowning.The aquatic recreation that produces the greatest

From the Department of Physical Medicine and Rehabilitation(Dr. Kewalramani), and the Department of Community Health(Dr. Kraus), University of California, Davis, School of Medi-cine, with the cooperation of the Northern California HospitalAssociation, Californa Hospital Association, Medical Record Li-brarian Associations, California Coroners and Public Administra-tors Association, and the State of California Departments ofHealth, Rehabilitation and Industrial Relations.Data for this research report were made available as a result

of an investigaticnal grant to Dr. Kraus from the Insurance Insti-tute for Highway Safety, Washington, DC.

Submitted, revised, August 17, 1976.Reprint requests to: Jess F. Kraus, PhD, Department of Com-

munity Health, University of California, Davis, School of Medi-cine, Davis, CA 95616.

number of spinal-cord lesions is diving. In fact,greater than 75 percent of all acute spinal-cordlesions that are recreation-related result from div-ing.' (Recreation-related spinal-cord injuries in-clude those associated with athletics, sportingevents, aquatic recreation, hiking [falls] and thelike. Such injuries from recreational motoring orhunting are classified as injuries from motor ve-hicle collisions or firearms.) The neurologicallesion is often severe enough to result in perma-nent tetraplegia.The incidence and epidemiologic features of

spinal-cord lesions from diving have not been re-ported aside from several clinical descriptions ofseries of cases. Presented here are the results of a

THE WESTERN JOURNAL OF MEDICINE 353

SPINAL-CORD LESIONS FROM DIVING

study of the incidence of acute traumatic spinal-cord lesions due to aquatic diving among residentsof 18 Northern California counties. This paperreports on the methods used in case ascertain-ment, overall incidence rates, human and environ-mental factors associated with the injuries, andthe clinical features of all incidence and preva-lence cases identified.

Methods and MaterialsThe methods used in case ascertainment for

the study of traumatic spinal-cord lesions in 18Northern California counties have already beenpresented elsewhere.' For completeness, this re-port recapitulates important methodologic con-siderations.

Definition of Spinal-Cord Injuryand Incidence Criteria

For the purposes of this study, a spinal-cordlesion was defined as an acute traumatic lesionof the spinal cord, including trauma to nerveroots that results in sensory or motor deficit, orboth. The diagnosis of spinal-cord injury anddescription of the resulting deficits were acceptedas recorded by an attending physician in the hos-pital admission or discharge record, autopsy pro-tocol or other medical record. All informationused was obtained from existing records, not byinterview.

For inclusion as an incidence case, the injurymust have occurred in 1970 or 1971 to a usualresident of the 18 prespecified Northern Califor-nia counties (regardless of place of occurrenceor place of treatment of the injury). The years1970 and 1971 were selected to utilize 1970United States Census data as a denominator inderiving incidence rates according to sociodemo-graphic factors.

Reference Population and Geographic RegionThe population at risk was defined as the usual

residents of the 18 Northern California counties,a population (1970 United States Census) ofslightly more than 5.8 million persons (29.1 per-cent of the state's population). The counties in-volved included Shasta, Tehama, Nevada, Placerand El Dorado (mountain region); Butte, Yuba,Sutter, Yolo, Sacramento, San Joaquin and Solano(central valley region); Contra Costa, Alameda,Marin, San Francisco, San Mateo and SantaClara (coastal region).

TABLE 1.-Hospital Admission Indexing Code Numbersand Rubrics Used for Spinal-Cord Injury Case

Ascertainment*

RubricNo.* Rubric

349 ...... Other diseases of spinal cord (mono-,hemi-, para-, quadriplegia)

725 ...... Displacement of intervertebral disk772.1 ...... Birth injury without mention of cause805 ...... Fracture and fracture dislocation of verte-

bral column without mention of spinal-cord lesion

806 ...... Fracture and fracture dislocation of verte-bral column with spinal-cord lesion

839 ...... Other dislocation: spine958 ...... Spinal-cord lesion without evidence of

spinal-bone injury959 ...... Other nerve injury03 ...... Surgical operations: operations on spinal-

cord structures

International Classification of Diseases, Adapted, 8th Revision.2

Method of Case AscertainmentCase ascertainment involved a systematic, ex-

haustive review of records, files and reports iromall hospitals and coroner's offices in each countyand records of the State of California Depart-ments of Health (Crippled Children's Service),Rehabilitation and Industrial Relations (Work-men's Compensation). There were three phases tocase ascertainment: (1) review of all hospital ad-mission records (the principal method of ascer-tainment); (2) examination of all autopsy proto-cols* for evidence of spinal-cord lesions, and (3)review of all records on file with the State ofCalifornia Departments of Health (Crippled Chil-dren's Service), Rehabilitation and Industrial Re-lations (Workmen's Compensation) to identifyspinal-cord injuries possibly missed in the pre-vious two phases.

Before case ascertainment through examinationof hospital admission records, indexing rubricswere examined to determine which could bestidentify those admitted to hospital with a potentialspinal-cord injury. All hospitals used the In-ternational Classification of Diseases, Adapted(ICDA) , the hospital adaptation of ICDA3 or, toa lesser extent, the Standard Nomenclature ofDiseases and Operations.4 Tests of potential ru-brics at hospitals led to adoption of a final list ofnine hospital admission and discharge rubrics(Table 1). The medical record of each potentialcase with one or more of these rubrics was ex-amined to determine conformance with the defi-

*California law requires that all perscns who sustain an unex-pected, sudden, violent, or unattended death shall have a port-mortem examination and a coroner's investigaticn (Section 27491,California Government Code).

354 MAY 1977 * 126 * 5


nition of spinal-cord injury and whether the inci-dence criteria were met.

Case ascertainment was begun in October 1972and completed in January 1974. Several monthswere devoted to case ascertainment outside the18-county region to identify persons with aspinal-cord injury who were usual residents ofthe 18-county region but injured elsewhere. Forthis purpose, admission records of major hospitalsin counties on the periphery of the 18-countystudy region were used (that is, the remainder ofCalifornia, western Nevada and southern Oregon).A complete search was made of the files of theState of California Crippled Children's Service,Department of Rehabilitation and Workmen'sCompensation, to identify all possible cases whichmet the criteria of incidence. Autopsy protocolswere reviewed from 30 of the most populouscounties in California, western Nevada and south-ern Oregon.

Data on the numbers of swimming pools in eachof the 18 counties (limited to the type of poolbuilt in the ground) were obtained from a privatecommercial firm (personal communication, BakerAdvertising and Mailing, 3923 West 6th Street,Los Angeles 90020). Data on the numbers oflakes and reservoirs as well as miles of rivers andstreams in the 18-county region were obtainedfrom the State of California Department of Fishand Wildlife.

ResultsEpidemiologic Features

Incidence. In all, 45 persons with confirmedacute spinal-cord lesions due to diving were iden-tified from the records reviewed. Twelve did notmeet residency and year of injury criteria. Theremaining 33 persons among the 5.8 million resi-

dents of the 18-county area gave an average an-nual incidence rate of 2.8 per million population.Incidence was about the same for 1970 and 1971.Incidence by age, sex, racial-ethnic group or typeof body of water involved was not related to yearof occurrence. The single death (dead on arrival)among the 33 cases gives a fatality rate of 3 per-cent. (In all 45 cases there were two deaths.)

Age, Sex and Race-Ethnicity. Table 2 gives thenumbers and rates of injury by age and sex. Withboth sexes, peak incidence was from 15 to 19years of age. Incidence rates were about six timesas high for males as for females. Persons in thegeneral population at greatest risk were malesaged 15 to 19 years. None of the persons wereunder thirteen or over 44 years old. At the timeof the 1970 United States Census, slightly greaterthan 12 percent of the population of the studyarea was Mexican-American, and 7.3 percent wasblack. On the basis of the percentage distributionof the general population by race-ethnicity, theinjuries would have been expected to involve fourMexican-Americans and two blacks. In fact, twoMexican-Americans were identified, but noblacks, a difference which was not statisticallysignificant.

External Cause and Types of Bodies of Water.Incidence cases involved diving, except one som-ersault into a swimming pool. There were nospinal-cord injuries from waterskiing, surfing orboating. Table 3 gives a distribution according totype of body of water and age of injured person.Of the 33 cases, 15 (45 percent) resulted fromdiving into a river or stream. Swimming poolswere second in frequency (27 percent). Distribu-tion by age differed with each of the major groupsof bodies of water. For example, six of the nineinjuries in swimming pools involved persons 25

TABLE 2.-Number and Average Annual Incidence of Spinal-Cord Lesions from Diving According to Age and Sex,18 Northern California Counties, 1970-1971

Sex

Male Female Both Sexes

Rate RatePersons Population per Persons Population per

Age* Injured at Risk Million Injured at Risk Million

10-14 ..... 3 286,930 5.2 1 277,077 1.815-19 ..... 10 260,408 19.2 3 256,429 5.820-24 ..... 4 251,388 8.0 0 265,92525-34 ..... 6 403,437 7.4 1 404,889 1.235-44 ..... 5 343,047 7.3 0 349,306

All agest. 28 2,853,297 4.9 5 2,947,653 0.8

*There were no reported cases for persons 0-9 or over 44 years of age for either sex.tRates calculated on the basis of the populations of 18 Northern California counties combined.

Rate.Persons Population perInjured at Risk Million

413475

33

564,007516,837517,313808,326692,353

5,800,950

3.512.63.94.33.6

2.8



TABLE 3.-Number of Persons with a Spinal-CordLesion from Diving by Age and Type of Body of Water,

18 Northern California Counties, 1970-1971

Type of Body of Water

River,Swimming Stream, All

Age Pool or Creek Lake Ocean Types

10-14 ......... 1 3 0 0 415-19 ......... 2 5 4 2 1320-24 ......... 0 4 0 0 425-34 ......... 3 2 1 1 735-44 ......... 3 1 1 0 5

All age groups .. 9 15 6 3 33

years old or above, whereas 16 of the 21 injuriesin rivers, lakes and streams involved persons 24years of age or younger.

Other Factors. Spinal-cord lesions occurred ex-clusively in May through September, peaking inthe three middle months; 3 in May, 9 in June, 9in July, 8 in August and 4 in September. Therewere too few cases for statistical test of any rela-tion between month of injury and age; however,the ratio of observed to expected frequencies washighest for those 25 years old or above injured inMay and September (Table 4).

The injuries were not distributed evenlythroughout the week. Of the 33 injuries, 12 wereon Sundays, 5 on Saturdays, 4 on Mondays, 5 onTuesdays, 3 on Wednesdays and 2 each on Thurs-days and Fridays. Day of occurrence was not re-lated to age (<25, .25 years).

Injury rates were not calculated by county ofresidence because the numbers were so low foralmost all of the counties. However, incidence washighest (5.9 per million) for the mountain coun-ties, intermediate (4.4 per million) for the centralvalley counties and lowest (2.2 per million) forthe north coastal counties. The ratio of spinal-cord lesions per 1,000 in-ground swimming poolswas highest in the mountain counties (8.5 per1,000 pools), and lowest in the valley and coastalcounties (0.5 and 0.2 per 1,000 pools, respec-

tively). It should be noted that the ratio for themountain counties was based on a single injuryper 118 in-ground pools. The ratio of injuriesper 1,000 miles of rivers and streams for each ofthe three areas was highest for the coastal counties(9 per 100 miles) and lowest for the valley andmountain counties (0.3 and 0.2 per 100 miles,respectively). The information available to usgave no data on water depths, or heights andtypes of dives.

Although the injuries were too few for a sta-tistical test of significance, excess numbers of per-sons with tetraplegia were associated with divinginto a lake, a quarry or the ocean, and excess in-stances of persons with tetraparesis were associ-ated with diving into swimming pools (Table 5).Similarly, no statistical test could be made of as-sociation between age and neurologic impairmentlevels since three of six cells (Table 6) had ex-pected frequencies of less than five. However, thenumber of tetraplegics was higher than expectedfor those less than 25 years of age.

Clinical Features

The spectrum of neurologic injuries observedin all 45 cases identified (33 incidence, 12 preva-lence) varied from no sensory and minimal motordeficit to complete sensory motor tetraplegia.Three patients with fractures of neural arches ofC1-4, wedge fractures of C5 and subluxation ofC2-3 and C3-4 were neurologically intact on ad-mission, although all had severe paresthesias atthe time of injury. Three patients with only mini-mal motor weakness of one upper extremity hadfractures of neural arches of C5 and C6 andwedge fracture of C6. Ten patients had clinicalfeatures of acute central cervical cord syndromewith various degrees of sensory and motor loss.A total of 27 patients (21 <25 years of age and6 >25 years of age) were completely tetraplegicat admission, and only 1 of these showed func-

TABLE 4.-Number and Ratio of Observed to Expected* Frequencies of Spinal-Cord Lesionsfrom Diving by Month of Occurrence and Age, 18 Northern California Counties, 1970-1971

Month of Occurrence NuimberAge Group Observed,

(years) May June July August September All Months

<25 ......... 0.5 1.1OBS/EXP .... (1/1.9) (6/5.7)>25 . 1.8 0.9OBS/EXP .... (2/1.1) (3/3.2)Number observed,

all ages ....... 3 9

*Based on rowXcolum+.-total number observed.

356 MAY 1977 * 126 * 5

0.9(5/5.7)

1.3(4/3.2)

9

1.6(8/5.1)

0.0(0/2.9)

8

0.4(1/2.5)

2.0(3/1.5)

21

12

4 33

,


tional neurologic return and achieved independentambulation. Of the 27 patients with tetraplegia,there were two physiologic transections of thespinal cord at C4, fourteen at C5, ten at C6 andone at C7. The distribution of locations of tran-sections of the spinal cord was not related to ageof the patient or type of body of water. Two pa-tients were admitted in a comatose state withflaccidity, areflexia and tetraplegia possibly sec-ondary to intracranial injuries. These two patientsdied two and four days, respectively, after hos-pital admission, and results of autopsy showedbilateral cortical softening, severe maceration ofthe spinal cord, and fracture dislocation of C3on C4 and C5 on C6.

Of 13 patients with bradycardia (pulse rate 60per minute or below), hypothermia and hypoten-sion, there was functional return in only one; theothers remained tetraplegic. Those 13 patientswith a systolic pressure of 100 mm of mercury orbelow, with or without bradycardia, also remainedtetraplegic.

Most of these patients reported difficulty inbreathing, and had been rescued by personsnearby at the time of injury. Only three of thesepatients had scalp lacerations, suggesting that

they struck the bottom of the water reservoir orhard objects.Two patients with no previous history of peptic

ulcer disease developed stress ulcers four to sixweeks after the injury, and one of these developedperforation of a duodenal ulcer.The Queckenstedt test was carried out on six

patients. Three in whom there was a positive re-sult were found to have a contused or maceratedspinal cord on laminectomy. In one in whom testresults were equivocally positive, the spinal cordwas reported to be edematous. Those four pa-tients remained tetraplegic. As to the two patientswith negative results on a Queckenstedt test, onehad acute central-cord syndrome and the otherhad minimal motor weakness of one upper ex-tremity.

Radiologic Findings. All 45 patients had injuryto the cervical spine. None had an injury to thethoracic or lumbar spine. Radiographic evidenceof osteoarticular injury was detected in 44 of the45 patients. The patient in whom there was noradiographic evidence of osteoarticular injury wasfound on autopsy to have a crush fracture of C3vertebral body with subluxation on C4. In all,there were 56 vertebral-body fractures in 40 pa-

TABLE 5.-Number of Persons with a Spinal-Cord Lesion from Diving by FunctionalImpairment Level and Type of Body of Water, 18 Northern California Counties, 1970-1971

Impairnment Level

Other NeurologicTetraplegia* Tetraparesis DeficitNumber Number Number All

Type of LevelsBodies of Water Observed Expectedt Observed Expected Observed Expected Total

Swimming pool . 1 ( 4.1) 5 (2.7) 3 (2.2) 9River/stream ... 7 ( 6.8) 5 (4.5) 3 (3.6) 15Lake/ocean .... 7 ( 4.1) * (2.7) 2 (2.2) 9

All types ...... 15 (15.0) 10 (9.9) 8 (8.0) 33

*Includes one in-hospital death.tExpected values based on column totalXrow total-. total number of cases (e.g., 15X9--33=4.1).

TABLE 6.-Number of Persons with a Spinal-Cord Lesion from Diving by FunctionalImpairment Level and Age, 18 Northern California Counties, 1970-1971

Impairrnent Les'el

Other NeurologicTetraplegia Tetraparesis DeficitNumber Number Number All

LevelsAge Group Observed Expectedt Observed Expected Observed Expected Total

<25 ......... 12* ( 9.5) 5 ( 6.4) 4 (5.1)>25 ......... 3 ( 5.5) 5 ( 3.6) 4 (2.9)

All age groups. 15 (15.0) 10 (10.0) 8 (8.0)

*Includes one in-hospital death.tExpected numbers calculated on the basis of column totalXrow total--total number of cases

ke.g., 15X21÷.33=9.5).


2112

33


TABLE 7.-Osteoarticular Injuries from DivingAccording to Vertebral Level, 18 Northern

California Counties, 1970-1971Fractures Luxations

Vertebral Neural Sublux- Dislo-Level Body Arch Level ation cation

C1 1 C1/2 1C2 2 C2/3 1C3.... 3 2 C3/4 4C4.... 8 2 C4/5 7 2C5 ....28 10 C5/6 11C6 ....15 3 C6/7 3 2C7.... 2

ToTAL . 56 20 27 4

TABLE 8.-Number of Persons Sustaining Wedge Frac-tures from Diving According to Vertebral Level andTypes, 18 Northern California Counties, 1970-1971

Number of Persons with at Least One Wedge Fracture

One Wedge Two WedgeVertebral Plus PlusLeiel of One Wedge Two Wedge Additional AdditionalFracture Fracture Fractures Fracture Fracture

C3. 22C4. 0C58...... .C6. 4C3-4 1C4-5 3 3*CS-6 6 1 1*

All levels 14 10 4 1* Includes additional burst fracture.

tients (Table 7). A total of 16 patients had frac-_tures at two levels, and all the fractures were ofadjacent vertebral bodies in continuity. In 24patients there was fracture at one level only. Moreolder persons (.25 years) than expected had afracture at a single level of the cervical vertebrae(x2 =6.45, p=0.01). Excess numbers of pa-tients with fractures at two levels of the spinewere associated with dives into rivers and lakes(x2=3.95, p=0.05). Of the 56 vertebral-bodyfractures, there were 40 wedge, 11 burst and 5teardrop fractures. The type of vertebral bodyfracture was not associated with the age of thepatient or the type of body of water. In 12 pa-tients there were fractures of the posterior ele-ments or neural arches. In 11 of the patients withfractures of the neural arch there also were asso-ciated vertebral-body fractures.Wedge fracture was the most common type of

osteoarticular injury. There were 40 wedge frac-tures in 29 patients. In 14 of these patients therewere single wedge fractures and in 10 two wedgefractures. Four patients had a wedge fracture anda burst fracture in the adjacent vertebral body.

One patient had two wedge fractures and a burstfracture in the adjacent vertebral body. The dis-tribution of wedge fractures by vertebral level isgiven in Table 8. For those with a single wedgefracture, the most common level was the C5vertebral body. For those with two wedge frac-tures the C5-6 vertebral bodies were most com-monly involved.

There were 25 patients with subluxations atvarious levels. In addition, there were 4 patientswith dislocations of the cervical vertebrae (Table7). Of the 29 patients with subluxations and dis-locations, 28 also had a fracture of a vertebralbody or of posterior processes of a vertebra.

Myelograms were carried out on eight patients.Three patients with evidence of myelographicblock had a swollen, contused, or maceratedcervical spinal cord at the time of operation, andall three remained tetraplegic. Two other patientswith myelographic block had a normal-appear-ing spinal cord on laminectomy, and only onehad a functional neurologic return. Three pa-tients with no myelographic defect had centralcervical-cord syndrome, and two of the three hadexcellent neurologic recovery.

Management. Initially, all patients with radio-logic evidence of injury to the cervical spine wereimmobilized and Vinke, Crutchfield, or Cone-Barton tongs were applied for skull traction. Fivepatients were placed in a Halo body cast withoutany complication. Decompression laminectomywas carried out on nine patients on the day ofinjury, and on one patient four days after theinjury. Three of the laminectomies were doneconcomitantly with posterior fusion and wiring.In one patient anterior interbody fusion was done,in addition to laminectomy and posterior fusion,and in another patient who had a laminectomyon the first day, anterior fusion was done becauseof instability nine weeks later. One patient whohad made good recovery following central-cordsyndrome had posterior fusion done 12 weekslater because of the persistent instability. Anteriordecompression and interbody fusion by Clowardor Smith-Robinson technique were carried out on12 patients: on seven within one week of thetrauma, and on five from 2 to 16 weeks follow-ing the injury.

Correlation of Radiographic Findingsand Neurologic Return

Radiographic abnormalities of the cervicalspine are of little significance in the absence of

358 MAY 1977 * 126 * 5


neurologic deficit. Hence, the different types ofosteoarticular injuries were compared with neuro-logic recovery of residual deficit.

Eleven burst fractures were present in nine pa-tients, associated with variable degrees of sub-luxations in eight of them. Teardrop fractureswere present in five patients. Three of them hadcentral-cord syndrome and made an excellentrecovery, and the other two had second- andthird-degree subluxation, with complete tetra-plegia that remained unchanged on dischargefrom hospital.

Forty wedge fractures were seen in 29 patients.Eighteen of these patients remained tetraplegic.Three of four patients with wedge and burst frac-tures at different levels remained tetraplegic. Onepatient with a wedge and teardrop fracture at twolevels also remained tetraplegic.Of 16 patients with fractures of two vertebral

bodies, 12 had complete tetraplegia. Of these 12patients, there was functional recovery in onlyone.

Dislocation or third-degree subluxation waspresent in four patients; all were tetraplegic. Theirneurologic status remained unchanged on hospitaldischarge. Of 24 patients with subluxation, 22had associated fractures of vertebral body orneural arch, or both.

Functional ImpairmentOf the total 45 patients, six had minimal sen-

sory or motor deficit and within a week were freeof any detectable neurologic abnormality. Tenpatients with acute cervical central-cord syn-drome showed good improvement, and all but onewere independent in their activities of daily living6 to 12 months after the injury. Five of these stillhad a mild residual sensory and motor loss. Hy-perreflexia and positive Babinski sign persisted inall these patients as long as they were followed.In all, 27 patients were tetraplegic at admission,and their impairment remained unchanged exceptthat one patient showed some functional returnand was ambulatory with crutches. Two patientsdied as a result of complications from intracranialinjury, and in both there was evidence of cervicalspinal-cord maceration on autopsy.

DiscussionThe National Institutes of Health have esti-

mated that the cost to society of spinal-cord in-jury is second only to that of mental retardation,among the neurologic and sensory disorders.5 Ofparticular significance in this respect are acute

traumatic lesions of the spinal cord as a result ofdiving, since these injuries always involve thecervical spine and the resulting neurologic deficit,if permanent, is tetraplegia. The actual incidenceof spinal-cord lesions in the United States fromdiving injuries is not known. Burke6 reported that8 percent of traumatic spinal-cord lesions inAustralia resulted from diving. Kewalramani andTaylor7 found that 18 percent of spinal columninjuries over four years were from diving. Thispercentage included those with spinal-column in-jury with and without a spinal-cord lesion. Of the619 spinal-cord lesions identified in the presentstudy, 5.3 percent were from diving, producingan average annual incidence of 2.8 per millionpopulation. Projected nationally, this rate indi-cates an annual total of 600 to 650 spinal-cordinjuries due to diving. This range may be an un-derestimate because many drownings may haveresulted from paralysis from spinal-cord injury. Amore thorough postmortem examination of per-sons who have drowned for evidence of spinal-cord damage could provide information on thisquestion.

Spinal-cord injuries from diving occur mostlyamong the young. Greater than 51 percent of thecases occurred among teenagers. The number ofpersons exposed to the risk of injury in diving byage and sex is unknown. Nonetheless, the tragicconsequences include a lifetime of permanent dis-ability for a substantial number of young people.

Interestingly, only one of the 15 cases withtetraplegia resulted from diving into a swimmingpool. In northern California in 1970 and 1971,there were about 35,500 in-ground public or pri-vate swimming pools. In the mountain counties,with only 118 pools, there was one case of spinal-cord injury. The frequencies of diving-relatedspinal-cord lesions in the valley counties (withabout 6,500 pools) and the coastal counties (withalmost 29,000 pools) were substantially lowerthan expected. Although the ratios of injuries per1,000 pools were based on a total of only ninecases, they suggest highest risk associated withleast opportunity of exposure.Of 15 cases of tetraplegia, 14 resulted from div-

ing into rivers, streams, lakes or the ocean. Thenumbers of lakes or reservoirs and the numbersof miles of rivers, streams and canals were se-

lected as indication of potential exposure to in-jury. The ratio of injury was highest in countieswith the least opportunity for exposure (coastalcounties) and lowest in those counties with the



greatest opportunity for exposure based on num-ber of miles of rivers and the like.

The anatomical site of injury in all cases wasthe cervical spine. In almost 60 percent of the 45cases identified, the patients were still completelytetraplegic at hospital discharge. The two patientswho died because of associated head injury alsohad destruction of the cervical spinal-cord whichwould have resulted in tetraplegia.

Information in some of the medical records in-dicated that patients had underestimated the depthof water, but only three patients had objectiveevidence (scalp laceration or hematoma) of hav-ing struck the bottom of a water reservoir or ahard object. Lack of functional recovery had a96 percent correlation (26 of 27 cases) with com-plete sensory or motor tetraplegia at admission;these patients remained permanently paralyzed.All ten patients with acute cervical central-cordsyndrome had significant functional return. Theother equally important predictor of neurologicoutcome with a 92 percent correlation (12 of 13cases) was impairment of autonomic function atadmission, that is, bradycardia, hypothermia orhypotension. Radiographic abnormalities were lessreliable predictors of functional return than wereclinical findings at admission. All the same, inmost of the cases, fractures at two levels of thecervical spine or burst fractures and dislocationwere suggestive of severe and permanent neuro-logic deficit.Wedge fractures are generally accepted to be

flexion injuries to the vertebral body. Sarpyener8postulated that severity of wedging was directly re-lated to the weight of the diver, height of the diveand depth of the water reservoir. This conclusionwas not based on experimental data, and, unfortu-nately, we have no data to confirm or refute thisconclusion. Flexion forces in combination withrotary motion would rupture the posterior liga-ment complex or, without rupture, cause fractureof tips of the spinous processes in addition towedge fracture. The present series included 29patients with one or more wedge fractures. Indiving it is the combination of flexion and verticalcompressive forces over the cervical spine thatresults in wedge, burst and teardrop fractures, andsubluxation or dislocation of vertebrae dependingupon the degree of initial flexion of the spine atthe time the person contacts the water surface.The angle of. projection, velocity of mass centerand angular momentum are established in thetakeoff of the dive.9 These factors play a major

role in determining the success of the dive, andthe alertness and expertise of the diver can modifythese factors considerably. Although alcohol orother drugs would probably affect alertness of thediver, no information was available on the use ofalcohol or other drugs preceding the injuries in-curred.

Burke6 concluded from the high percentage (88percent) of burst fractures in diving activitiesthat these were incurred from hitting the bottomof the water reservoir. In the present series,however, only 20 percent of the fractures wereburst fractures, with the other 80 percent beingwedge and teardrop fractures. Of the three pa-tients who had objective evidence (scalp lacera-tions) of having struck the bottom of a waterreservoir, only two had radiologic evidence of in-jury: wedge and burst fractures at two levels. Thisfinding would support our hypothesis that hyper-ventroflexion was the mechanism responsible forinjury in most of the cases. Because of the cus-tomary slight flexion of the neck in diving, impactwith the water surface tending to counteract themomentum of the falling body, would cause hy-perventroflexion or hyperretroflexion, dependingon the angle of entry into the water, perhaps be-ing great enough to produce the variety of frac-tures reported without any collision with thebottom or hard objects.

About 80 percent of the patients noticed aninability to move the upper and lower limbs im-mediately after the injury and also reported diffi-culty in breathing. All were removed from thewater by other persons. Most would probablyhave drowned if not rescued. Many persons whoparticipate in saving lives following diving injuryprobably have no knowledge of the water-rescueprocedures that would be proper when the spinalcord may have been injured. Conventional water-rescue procedures need to be revised in the lightof possible cervical spinal-cord injury in diving.Improper moves could aggravate the severity ofinjury.The problem of spinal-cord injuries should be

examined from an etiologic perspective as well asanatomic and pathologic points. Spinal-cord in-juries from diving result from the forces producedin the energy exchanges that result from impactswith the surface of the water or with hard ob-jects or structures in or under it. Haddon'0 hasidentified a series of strategy options for reducinglosses from energy exchange and related injuriessuch as drowning, an injury produced by inter-

360 MAY 1977 * 126 * 5


ference with normal energy exchange. Drawingon Haddon's analysis, some options for reducinglosses from diving include:

* Prevent the aggregation of water suitable fordiving or attempted diving (for example, do notbuild swimming pools).

* Reduce the amount of energy marshaled (toreduce the heights of diving boards for swimmingpools would be one preventive tactic illustratingthis option).

* Prevent (or modify the rate of) the releaseof the energy of the diver on the board (prevent-ing the untrained from using high boards andeliminating shallow water reservoirs are examplesof tactics for this option).

* Separate populations at risk and opportuni-ties (places) for diving (locating hazardous bodiesof water far away and fencing them illustrate thisoption).

* Modify the contact surface or basic structure(two important tactics involve softening the bot-toms of swimming pools or removing rocks, pil-ings or other hard obstacles from lakes, rivers andoceans where swimming and diving are practicedor are likely to occur).

* Strengthen divers to make them less suscep-tible to excess energy delivered to the body in adive (muscle strengthening exercises are a tacticillustrating this option).

* Increase the availability, speed and compe-tence of emergency medical care and transport(training in techniques to ensure nonaggravationof existing spinal-cord damage during proceduresto prevent drownings, or during emergency trans-port is one tactic that illustrates this option).

* Increase the availability of reparative andrehabilitative measures to stabilize the injury andrestore injured persons to maximum functionalstatus.

REFERENCES1. Kraus JF, Franti CF, Riggins RS, et al: Incidence of trau-

matic spinal-cord lesions. J Chron Dis 28:471-492, 19752. International Classifications of Diseases, Adapted for Use in

the United States, 8th Revision. Public Health Service Publica-tion No. 1693. US Department of Health, Education, and Wel-fare, Public Health Service, 1967

3. Commission on Professional and Hospital Activities: Hos-pital Adaptation of the sCDA, Ann Arbor, Michigan, 1968

4. Thompson ET, Hayden AC (Eds): Standard Nomenclatureof Diseases and Operations, 5th Ed. New York, McGraw-Hill,1961

5. Neurological and Sensory Disabilities: Estimated Numbersand Cost. National Institute of Neurological Diseases and Stroke,Public Health Service Publication No. 1427. US Department ofHealth, Education, and Welfare, Public Health Service, 1970(revised)

6. Burke DC: Spinal-cord injuries from water sports. Med JAustralia 2:1190-1194, 1972

7. Kewalramani LS, Taylor RG: Injuries to the cervical spinefrom diving accidents. J Trauma 15:130-142, 1975

8. Sarpyener MA: Cervical column injuries due to diving andfalling, In Proceedings of the IX Congress of International Soc.of Orthopaedic Surgery and Traumatology. September 1-7, 1963,366-372, Brussels: Imprimeries des Sciences

9. Miller DI: A comparative analysis of the take-off employedin springboard dives from the forward and reverse groups, InProceedings of the Fourth International Seminar on Biomechanics.Biomechanics 4:222-228, University Park Press, 1974

10. Haddon W: Energy damage and the ten countermeasurestrategies. J Trauma 13:321-331, 1973


Acute Spinal-Cord Lesions from Diving Epidemiological and

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