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(Stroke. 1996;27:1558-1563.)
© 1996 American Heart Association, Inc.
Articles |
Misdiagnosis of Symptomatic Cerebral Aneurysm
Prevalence and Correlation With Outcome at Four Institutions
the Neurovascular Surgery Program, Section of Neurosurgery, Yale University School of Medicine, New Haven, Conn (P.L.M., I.A.A., P.D.); Department of Neurosurgery, New York Medical College, Valhalla (R.T., T.A.L.); Division of Neurosurgery, Dartmouth-Hitchcock Medical Center, Dartmouth Medical School, Lebanon, NH (K.H., R.H.); and Department of Neurosurgery, School of Medicine and Biomedical Sciences, State University of New York at Buffalo (G.V., L.N.H.).
Correspondence to Issam A. Awad, MD, MSc, FACS, Professor of Surgery (Neurosurgery), Yale University School of Medicine, 333 Cedar St TMP 405, New Haven, CT 06520. E-mail issam.awad@yale.edu.
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Abstract |
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Background and Purpose It is not known what fraction of patients with symptomatic cerebral aneurysms are misdiagnosed at initial medical presentation. It is also not clear whether misdiagnosed patients more frequently deteriorate before definitive aneurysm diagnosis and therapy or achieve a poorer outcome than correctly diagnosed patients.
Methods We reviewed records of consecutive patients with symptomatic cerebral aneurysms managed by four tertiary-care neurosurgical services during a recent 19-month period. Clinical course and outcome were analyzed according to misdiagnosis or correct diagnosis at initial medical evaluation.
Results Fifty-four of 217 patients (25%) were misdiagnosed at initial medical evaluation, including 46 of 121 patients (38%) initially in good clinical condition (clinical grade 1 or 2). Forty-six of 54 patients (85%) in the misdiagnosis group were initially grade 1 or 2 compared with 75 of 163 patients (46%) with correct initial diagnosis (P<.01). Twenty-six of 54 misdiagnosed patients (48%) deteriorated or rebled before definitive aneurysm treatment compared with 4 of 165 correctly diagnosed patients (2%) (P<.001). Among patients initially presenting as clinical grade 1 or 2, overall good or excellent outcome was achieved in 91% of those with correct initial diagnosis and 53% of patients with initial misdiagnosis (P<.001). Deterioration before correct diagnosis accounted for 16 of 67 patients (24%) with poor or worse final outcome in this series.
Conclusions Patients in good clinical condition with symptomatic cerebral aneurysms were commonly misdiagnosed. Misdiagnosed patients were more likely than correctly diagnosed patients to deteriorate clinically and had a worse overall outcome. Misdiagnosed cases accounted for a significant fraction of overall poor outcomes among consecutive cases of symptomatic aneurysms.
Key Words: cerebral aneurysm • diagnosis • outcome • subarachnoid hemorrhage
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Introduction |
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Gillingham1 2 is credited with coining the term "warning leak" to describe signs and symptoms of a probable minor aneurysmal subarachnoid hemorrhage (SAH) shortly preceding a major one. If these signs and symptoms are properly recognized, medical intervention may proceed to treat the aneurysm and thus avoid a major hemorrhage and the very high morbidity and mortality associated with it.3 4 5 6 7 8
In fact, the concept of warning symptoms has been appreciated as part of the natural history of aneurysmal SAH for as long as the disease has been understood.9 10 11 12 Many other terms have since been used to describe these premonitory symptoms and signs (eg, "sentinel bleed," "sentinel headache," "minor leak," "warning headache"), which are reported as preceding major SAH in 5% to 70% of patients in various series, with an average of approximately 40%.2 3 4 5 Approximately half of affected patients seek medical attention before a major SAH, and 16% to 60% of these patients are misdiagnosed.3 4 5 14 15 19 22 25 26 The clinical course and outcome of misdiagnosed patients compared with those correctly diagnosed have not been well documented. We hypothesized that (1) symptomatic aneurysms are frequently misdiagnosed at initial presentation to medical attention, (2) correctly diagnosed patients are less likely to deteriorate before definitive aneurysm treatment, and (3) correctly diagnosed patients achieve better outcome than patients who are initially misdiagnosed. This study examines these hypotheses in a cohort of consecutive patients with symptomatic cerebral aneurysms managed at four tertiary-care neurosurgical centers.
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Subjects and Methods |
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Study Design, Inclusion and Exclusion Criteria, and Definition of Misdiagnosis
We performed a retrospective review of medical records of consecutive patients with symptomatic, subarachnoid, intracranial aneurysms during a recent 19-month period at four tertiary-care neurosurgical centers with various referral demographics. The study included all patients presenting with symptoms or signs due to aneurysmal hemorrhage (SAH, intracerebral hemorrhage, intraventricular hemorrhage), mass effect (cranial nerve palsy, chiasmatic compression, lateralizing neurological deficit), headache attributable to aneurysm (new or different from previous headache), hydrocephalus, thromboembolic ischemia, or seizure directly attributable to aneurysm. Excluded were patients with aneurysms entirely outside the subarachnoid space, nonaneurysmal SAH, headaches and seizures not clearly attributable to aneurysm, and asymptomatic, incidentally discovered aneurysms.
A misdiagnosis was said to have occurred if the initial medical evaluation did not consider the possibility of intracranial aneurysm or if the diagnosis of aneurysm was delayed by more than 24 hours from the time of presentation to medical attention with symptoms of intracranial aneurysm.
Study Parameters
Parameters noted in the record review included age, sex, presenting symptoms, time to medical attention after symptom onset, specialty(ies) of health professional(s) making initial medical contact(s), clinical grade (severity of symptoms and signs) at initial presentation, clinical grade at time of correct diagnosis, erroneous working diagnoses, time to correct diagnosis, time to neurosurgical attention (or appropriate managing service), hemorrhage before correct diagnosis, hemorrhage after correct diagnosis, neurological deterioration after initial presentation, reasons for repeated presentation to medical attention if initially misdiagnosed, method of correct diagnosis, modality of definitive aneurysmal treatment, timing of treatment, and clinical outcome.
We graded the severity of presenting signs and symptoms from 1 (least severe) to 5 (most severe) using a modified Hunt and Hess SAH clinical grading scale.27 Clinical grade was established as the best condition achieved within the first 24 hours after initial medical presentation. The grading scale was as follows: grade 1, headache or seizure only; grade 2, any meningeal symptoms and signs, isolated cranial nerve palsy, nausea, or vomiting; grade 3, any altered level of consciousness (Glasgow Coma Scale score <15) or any lateralizing deficits; grade 4, coma (abnormal posturing unilaterally or bilaterally); and grade 5, coma plus hemodynamic instability.
Clinical outcome was graded at 6 weeks or last clinical encounter according to a modified Glasgow Outcome Scale,28 as follows: excellent (no deficits, return to all premorbid activities); good (minimal deficits, nondisabling for the individual patient); fair (disabling deficits, patient independent in all activities of daily living); poor (disabling deficits, requiring assistance in activities of daily living); vegetative (vegetative survival only); and dead.
Statistical Methods
We performed statistical analysis of the data using Student's t test and a simple statistical software package on a Macintosh microcomputer with statistical significance assumed at the .05 level.
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Results |
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A total of 217 consecutive patients treated for symptomatic cerebral aneurysms were identified. Of these, 54 patients (25%) sought attention from a healthcare professional for symptoms or signs of cerebral aneurysm and were initially misdiagnosed as defined. Table 1
summarizes the study cohort by clinical grade at initial medical evaluation and by study center.
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Rates of misdiagnosis ranged from 13% at the center contributing the least total cases to 35% at the center contributing the largest number of total cases. Overall, misdiagnosis occurred in 46 of 121 patients (38%) initially in good clinical condition (clinical grades 1 to 2), in 6 of 56 patients (11%) drowsy on presentation (grade 3), and in 2 of 40 patients (5%) unconscious at presentation (grades 4 to 5).
Clinical Characteristics and Patient Demographics
Table 2 summarizes clinical characteristics of the study cohort. Patients presenting with hemorrhage were significantly less likely to be misdiagnosed than patients presenting with mass effect or seizure. The presenting symptoms and signs for the two groups are summarized in Table 3. Headache was the dominant symptom in both groups. The majority of headaches were sudden and severe ("thunderclap" type). They were usually associated with nausea, vomiting, photophobia, neck stiffness or pain, back pain, lightheadedness, visual disturbance, and/or altered level of consciousness. Headaches that were not obviously related to the aneurysm (eg, typical migraine, chronic headaches of uncertain etiology, muscle contraction headache) were not considered aneurysm symptoms for the purposes of this study. Altered level of consciousness (especially coma) was significantly more likely to be associated with a correct diagnosis.
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Diagnostic Evaluation
Table 4 lists the erroneous working diagnoses for the misdiagnosed patients. Seven of the eight patients with a misdiagnosis of "viral meningitis" had neither a CT scan nor a lumbar puncture. The one patient who did undergo CT scanning had evidence of SAH on the scan that was initially not recognized. Eight of nine patients with diagnoses of migraine or cluster headache had no such prior history. For the one patient with a migraine history, it was clearly noted in the record that the presenting headache was different from and worse than her usual migraine.
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The methods of diagnosis of patients in both groups were similar and conformed to the usual diagnostic procedures for cerebral aneurysms and SAH. These methods are indicated in Table 5. The vast majority had positive CT and/or MRI scans. The CT scan was either misread or negative as a result of the scan having been performed days to weeks after presumed SAH in eight (15%) of the misdiagnosed patients. However, the majority of misdiagnoses occurred because the possibility of symptomatic aneurysm was not entertained and imaging studies were not performed.
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The time to correct diagnosis after initial misdiagnosis was 0 to 2 days in 13 cases (24% of misdiagnosed cases), 3 to 7 days in 21 cases (39%), 8 to 30 days in 13 cases (24%), and more than 30 days in 7 cases (13%). The specialty of the healthcare professional with whom initial contact was made in cases of misdiagnosis is shown in Table 6. Patients were occasionally evaluated by more than one healthcare professional.
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Rebleeding and Deterioration
Twenty-six of 54 misdiagnosed patients (48%) rebled or deteriorated after initial presentation to medical attention and before correct diagnosis and definitive management, while only four rebleeds and no other deteriorations occurred among the 163 correctly diagnosed patients before definitive aneurysm management. This difference was statistically significant (Table 7). Deterioration before definitive aneurysm management accounted for 18 of 67 patients (27%) with poor or worse final outcome in the entire study cohort: 16 of 23 (70%) with poor or worse final outcome in the misdiagnosis group compared with 2 of 44 (5%) in the correct diagnosis group (P<.001). The time course of rebleeds and clinical deterioration among misdiagnosed patients included 12 such occurrences in the first 5 days after initial medical presentation, 11 occurrences in days 6 to 20, and 3 occurrences after day 20. Among correctly diagnosed patients, three of the four rebleeds occurred in the first 5 days after initial medical presentation. Misdiagnosed patients suffered 26 rebleeds and other deteriorations during 1518 patient-days from presentation to medical attention until correct diagnosis (0.02 events per patient per day), while correctly diagnosed patients suffered four rebleeds during 1652 patient-days from presentation to medical attention (and correct diagnosis) until definitive treatment (0.002 events per patient per day).
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Clinical Outcome
Table 8 summarizes the clinical outcome in misdiagnosed and correctly diagnosed patients. Ninety-one percent of correctly diagnosed patients initially in good clinical condition (grades 1 or 2) achieved excellent or good outcome compared with only 53% of patients in those same grades who were misdiagnosed (P<.001). Thirty-six percent of patients in good clinical condition (grades 1 and 2) who were misdiagnosed suffered a poor outcome compared with only 4% of such patients who were correctly diagnosed (P<.001).
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Discussion |
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The outcome of patients suffering a major SAH has been widely reported.17 19 29 30 31 32 33 34 35 Approximately one third suffer early mortality without treatment, one third undergo treatment with eventual death or significant morbidity, and one third survive after treatment with favorable outcome. The condition of the patient at the time of treatment is the most important predictor of outcome. An untreated ruptured aneurysm is predisposed to recurrent hemorrhage, often within hours or days of initial SAH. Rebleeding is associated with a 33% to 100% rate of major morbidity or mortality.
Patients commonly present new onset of severe headache or other neurological symptoms before demonstrated SAH.3 14 17 It is impossible in retrospect to know whether all these patients had an actual "warning leak" since there is not always evidence of actual SAH at initial presentation. The term "warning headache" or "warning symptom" is perhaps preferable for such retrospective determination. For the purpose of this study, we included all cases of symptomatic presentation of cerebral aneurysm to medical attention because it was difficult to ascertain "rupture" at the time of first clinical presentation, particularly among misdiagnosed patients and those presenting solely with headache. We carefully excluded by methodology any patients in whom the aneurysm was totally extradural (not vulnerable to rupture) and patients in whom symptoms could not be directly attributed to the aneurysm (chronic headache). We sought to identify the prevalence of misdiagnosis at various institutions and in association with various presenting symptoms. We also evaluated the clinical course and outcome of correctly diagnosed patients in comparison to those in whom diagnosis of aneurysm was not sought or established.
The clinical management of cerebral aneurysms is typically guided by neurosurgeons and neurologists. However, it is the primary-care health provider who has the optimal opportunity to suspect and establish this diagnosis. Headache is the cardinal symptom associated with clinical presentation of cerebral aneurysm. A recent large prospective study reported that 25% of patients presenting for medical attention with acute onset of a new severe headache were found to have had an SAH, and another 12% had other serious intracranial pathology.20 Primary-care providers evaluate a large number of patients with headaches (1.5% of all visits to primary-care physicians) and obviously cannot perform CT scans and lumbar punctures on all of them.25 36 37 38 39 Furthermore, the diagnostic algorithm to rule out a cerebral aneurysm is potentially invasive and expensive. Nonetheless, it has been shown that primary-care physicians can effectively screen for symptomatic aneurysms with high efficiency when sensitized to this problem.20
Signs and symptoms that suggest the diagnosis of symptomatic aneurysm have been reported and reviewed extensively over the past seven decades.1 2 3 4 5 6 7 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 26 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 Typical symptom presentations include (1) sudden severe headache, alone or associated with nausea, vomiting, and/or meningeal signs; (2) new severe headache, unlike previous headache pattern in patients with chronic headaches; (3) significant unilateral headache not conforming to other headache syndromes; (4) retro-orbital headache; (5) unilateral ocular symptoms (eg, third-nerve palsy or visual field cut), usually with retro-orbital headache; and (6) headache with altered level of consciousness. The CT scan without contrast will reveal SAH in more than 90% of cases, although the scan may be negative if it is performed more than 1 or 2 days after clinical onset. In these cases or if there is suspicion of possible SAH on CT scan, a lumbar puncture will reliably exclude SAH (although not aneurysm). A CT scan with contrast, MRI, or MR angiography of good technical quality will diagnose more than 90% to 95% of aneurysms.8 20 25 37 Catheter angiography confirms the diagnosis of aneurysm and allows optimal planning of definitive treatment of the aneurysm.
Finally, the proper management of patients with symptomatic aneurysms, once recognized, is also important. The approach used by all participants in this study was similar and conforms to current published guidelines for SAH management.8 It included regulated bed rest; control of overt hypertension; use of anxiolytics, sedatives, and analgesics; and preparation for definitive aneurysm treatment as rapidly as possible for the individual case. This strategy appears to have greatly reduced the rate of aneurysmal rebleeding before definitive treatment compared with patients who were misdiagnosed (and not subjected to such management) and with the natural history of the disease as previously reported in the literature.12 29 30 31 32 33 34 35 57 58 59
In this study misdiagnosis of symptomatic aneurysm was most likely in the setting of headache alone and without more overt neurological symptoms and signs. Yet these patients presented the best opportunity to treat the aneurysm with good outcome. Patients with headache invariably stated that this was a more intense or otherwise different headache than usual, and this was often noted in the medical record. While the diagnosis of cerebral aneurysm rarely eluded simple and widely available modalities (CT, MRI, and lumbar puncture), it was most frequently missed because it was not considered and simple tests were not done. In patients in whom correct diagnosis was promptly established, the rates of subsequent deterioration and of untoward outcomes were significantly decreased.
This is the first published report documenting the prevalence of initial misdiagnosis among consecutive patients with symptomatic aneurysms presenting to four different tertiary-care centers. It highlights the frequency of this problem, particularly among patients in good clinical condition, and demonstrates that most patients should not be misdiagnosed when commonly available modalities and published guidelines are used.8 The study also supports the hypothesis that initially misdiagnosed patients achieve a worse eventual outcome than those in similar clinical condition who are promptly diagnosed and treated.
These results must be interpreted within potential biases of study design and referral to the four institutions. It is possible that patients who were misdiagnosed had features of symptomatology, demographic background, aneurysm or host characteristics, or medical comorbidity inherently predisposing to misdiagnosis or to poor outcome that were not identifiable by retrospective analysis. While all consecutive patients with symptomatic aneurysm managed at the four institutions were included in the study regardless of how or where they initially presented to medical attention, it is possible that patients who were referred to these institutions were inherently more likely to have been misdiagnosed. Other patients not referred to these institutions may not reflect similar rates or consequences of misdiagnosis. Future studies should examine these same hypotheses prospectively and in population-based cohorts. Specific protocols and referral and diagnosis guidelines should be disseminated to primary-care and emergency department physicians, and their impact on rates of misdiagnosis and overall outcome should be monitored and documented. A policy of "facilitated access" to specialized opinion for possible symptomatic aneurysm should replace prevalent "gatekeeper" paradigms in emerging managed-care models. It is likely that major impact on outcome of this disease may be accomplished through such strategies of improved diagnosis and timely referral and treatment.
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Acknowledgments |
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We acknowledge the contributions of David Chang, Yale MS3, for the compilation of data forms, Elizabeth Claus, MD, PhD, for assistance with statistical analyses, and Linda Barbato for manuscript preparation.
Received February 7, 1996; revision received May 20, 1996; accepted May 20, 1996.
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