The clinical picture in occult hydrocephalus.

21 The Clinical Picture in Occult Hydrocephalus" C. MILLER FISHER, M.D.

INTRODUCTION

In 1959 there was admitted to the Massachusetts General Hospital on the service of Dr. R. D. Adams a woman aged 63 who 6 months before had insidiously developed a peculiar wobbling gait, 3 months later forgetfulness, slowness and difficulty concentrating, and for several weeks urinary incontinence (1). In the pneumoencephalogram there was hydrocephalus, the ventricular span measuring 70 mm. A lumbar puncture before the pneumoencephalogram showed an initial pressure of 174 mm. H 20. After the pneumoencephalogram the patient became profoundly abulic and remained so during the following 5 weeks. Another lumbar puncture showed an initial pressure of 300 mm. H 20. The patient vomited from time to time. Because of hydrocephalus, increased intracranial pressure, and vomiting, ventriculoatrial shunt was installed by Dr. William Sweet with remarkable improvement in the patient's condition. After 30 days, although greatly improved, she was still not back to her state on admission. Six weeks after shunting she fell fracturing her left hip. Two days later she had again become slow, lethargic, inactive, drowsy, and forgetful. A lumbar puncture showed an initial pressure of 240 mm. H 20. The plastic connection between the valves of the shunt tubing had been broken in the fall and when drainage was restored 6 days after the fall, 4 days after deterioration of her condition, dramatic improvement occurred in 24 hours. In the next month the patient's family reported that not only was she back to her condition on admission but she had returned to her normal mental state with her usual animation and mental acuity. On reviewing the puzzling course of events in this case, it seemed that the patient's underlying illness had been communicating hydrocephalus and not cerebral atrophy as I had first thought. Furthermore, the communicating hydrocephalus must have caused progressive symptoms for they had been reversed

* Supported in part by National Institute of Neurological Diseases and Stroke Grant NS 05152. 270

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by shunting. The temporary exacerbation of symptoms when the shunt tubing was damaged proved that the original postshunt improvement was not a coincidence. Yet the resting cerebrospinal fluid (CSF) pressure on admission had been only 174 mm. H 20. It was tentatively suggested that hydrocephalus may be symptomatic even when the spinal CSF pressure is normal. The author having a penchant for identifying any unusual clinical phenomenon or state by applying a name tag to it, one day, as Dr. Salomon Hakim and I left the patient's room, the term "symptomatic normal pressure hydrocephalus" was proposed as a working label for the condition. (Dr. Hakim had previously performed a ventriculoatrial shunt and reversed a stuporous state in a young hydrocephalic patient whose CSF pressure was normal (7). The hypothesis suggested by the name tag was strengthened 4 months later .when there came to postmortem an elderly retired general of the United States Army who for 6 years had been a diagnostic problem because of difficulty with balance, falling, moderate dementia, and urinary incontinence. The CSF had been normal in all respects. When the brain was sectioned by Dr. E. P. Richardson at the weekly neuropathologic conference, the only abnormal finding was massive ventricular enlargement. Cerebral atrophy was minimal. Review of the details of the case supported the idea of normal pressure hydrocephalus and suggested that the first case was not necessarily unique. The next patient with a similar clinical picture at the Massachusetts General Hospital was a 62 year old physician who proved to have greatly enlarged lateral ventricles as the result of a third ventricular cyst. He too was restored to normal when shunted by Dr. Robert Ojemann and the general thesis concerning hydrocephalic symptoms was confirmed. The term symptomatic normal pressure hydrocephalus was chosen to underline the fact that hydrocephalus with a normal pressure was not necessarily a burnt out stable state, as was the view current at that time, but could be associated with progressive manifestations which were reversed by lowering the pressure to still lower values. It was not meant in any way to suggest that ventricular enlargement developed under conditions of normal pressure, and from the beginning we assumed that initially the pressure had been elevated. The term "low pressure" hydrocephalus has been used at times but is better avoided. Since it is now appreciated that hydrocephalus may be symptomatic whether the pressure is normal or elevated, the term symptomatic occult hydrocephalus or the hydrocephalic syndrome might be considered sufficient to define the state regardless of the pressure. When papilledema is present, an elevated pressure is assumed and when it is absent and the pressure is unknown the words "without papilledema" can be appended. However, it cannot be denied that the term normal


CLINICAL PICTURE IN OCCULT HYDROCEPHALUS

CLINICAL NEUROSURGERY

pressure hydrocephalus is still useful for designating the chronic process and setting it apart from acute high pressure events. When sought for, elements of hydrocephalic symptomatology can be recognized as a frequent component of the clinical picture in all disease processes interfering with the circulation of the cerebrospinal fluid. CASE MATERIAL

Since 1959, at the Massachusetts General Hospital some 60 adult cases of hydrocephalus with normal CSF pressure (or without papilledema) have been treated by shunting procedures because of cerebral symptoms. For this presentation I have analyzed 30 of these cases of varied types. From an analysis of the results of shunting an attempt has been made to determine the symptoms and signs which are to be attributed solely to hydrocephalus and which may therefore be used in selecting candidates for surgery. In 16 of the 30 cases definite improvement occurred after shunting. In one, improvement was temporary and brief, in 11 treatment was a failure and in two a functional shunt was not achieved. The 16 cases whose symptoms were reversed by surgery have been used to identify the clinical characteristics of hydrocephalus. The cardinal features of the syndrome that have emerged from previous analyses are dementia, gait disturbance and urinary incontinence. Particular attention has therefore been devoted to these three features but in addition observations have been made concerning other manifestations such as abulia, seizures, reflex changes, etc. The many negative clinical characteristics have also been noted. Because the severity of the neurological deficit in the hydrocephalic syndrome ranges widely from slight symptoms on one hand to a helpless, stuporous state on the other, rating scales were drawn up to assist in grading the degree of impairment of mental function, gait, and control of micturition (Table 21.1).

Disturbance of Gait A gait disorder was present in all 16 cases. It varied from mild to an inability to walk, stand, or even turn over in bed. An important feature that emerged was that a disturbance of gait was the earliest or first symptom in 12 of the 16 cases. Disturbance of gait and a change in mentation had their onset at about the same time in three cases and in only one case was mental change noted first. In this single case it was possible that the patient, aged 73, was in the early stage of Alzheimer's disease when hydrocephalus supervened. In seven representative cases the gait disturbance preceded mental change by the following intervals:


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TABLE 21.1 Rating Scales for Gait, Mentation, and Micturition

Range

Gait

Mentation

10

Normal gait Normal gait, unable to walk tandem

Normal Abnormal by history, but 3/3 items recalled at 3 min. 2/3 items, oriented to date 2/3 items, disoriented to date 1/3 items, oriented to place

9

8

7 6

5 4

3

2

Staggering gait without falling History of falling, Romberg posi tive History of falling, unable to stand with feet together Needs to touch objects in walking, uses cane Uses a walker, takes few steps alone Unable to stand

1

Needs support in walking Unable to sit or stand

o

Unable to walk

1/3 items, disoriented to place 0/3 items, disoriented to date 0/3 items, disoriented to place 0/3 items, disoriented to date and place Slight delirium, confusion or nonsensical talk Severe delirium, confusion or nonsensical talk

Micturition

Normal Urgency, nent

but

conti-

Incontinent less than once weekly

Incontinent more than once weekly

Incontinent daily

Incontinent regularly

3 months, 6 months, 2 years, 3 years, 3 years, 6 years, and 10 years respectively. Three of the 16 patients had only an inobvious mental change that was not apparent to either the family or the first examining physician, and was only disclosed by formal intellectual testing. The gait disturbance was rated as more severe than the mental in 7 of the 16 patients, they were equal in seven, and mental disturbance was slightly worse in one. By contrast, of the 11 patients in whom shunting failed to bring improvement, mentation was disturbed first in nine, mentation and gait were involved together in one, and gait disturbance was first in only one. Furthermore, of the nine cases with mental change first, in two there was no disturbance of gait, in six the gait disturbance was rated as slight and relatively less severe than the changes in mentation, and in only one were they equally severe. If these data are reliable it can be concluded that the predominant and most constant hydrocephalic symptom or sign is a disturbance of walking and standing. A change in mentation may accompany or follow gait disturbance but not precede it. Review of a further six cases of success-


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fully shunted patients has demonstrated the reliability of this finding. Also, in 5 of the 16 patients symptoms recurred when the shunt became obstructed and in each instance the recrudescence of symptoms followed the same order of appearance. When the patient is bed-ridden from a preceding illness (operation, trauma, subarachnoid hemorrhage) a disturbance of gait may be overlooked. The disturbance of gait is difficult to categorize neurologically. Terming it "gait apraxia" lends little clarification. All 16 patients gave a history of one or more falls while walking, standing, or bending over. Superficially the impediment appears to be a matter of balance rather than weakness, spasticity, or sensory loss. The nature of the imbalance has defied analysis but may represent a slowness in correcting a potential instability and not a frontocerebellar deficit, particularly since progression leads to immobility rather than ataxia. Or two factors may be combined. Descriptions by patients have included unsteadiness, "tipsy," staggering, weaving, slightly drunken, losing balance on bending over in dressing or picking up things, fear of falling (sometimes of an unnatural degree), unsteady on turns, stumbling on steps or curbs, ease of tripping, unsteady going down stairs or up stairs, a need to touch things in walking, or use a cane or someone's arm, and difficulty in backing up to sit down. Five of the 16 patients gave a history of falling down and being temporarily unable to get up and walk for 2 to 6 hours afterwards. In the progressively more advanced stages of hydrocephalus, the patient requires a walker and becomes unable to stand or sit even when the patient is supported, the legs although not weak cannot be placed in proper relationship to the center of gravity of the body and as the trunk is carried forward the feet slide, make aimless movements, or are dragged behind. Finally, the patient is unable to sit up from the lying position and is unable to turn over in bed as frontal truncal apraxia becomes fully developed. Yet while lying in bed voluntary motion of the legs is retained. Only 2 of the 16 patients complained of an associated dizzy, giddy, or swaying feeling in the head while the others disclaimed a sense of imbalance in the head. Vertigo, complained of by one patient, was probably due to a separate labyrinthine disturbance. Examination of the gait shows the step shortened compared with normal and at its worst reduced to 2 to 4 inches. The rate of steppage is normal early, but later it is slowed. The base is widened and varies from step to step as staggering occurs. The patient may lose his balance on turns. The toe or heel may be scuffed as the patient shuffles along. The most frequent direction of falling is backwards but any direction is possible. It is unusual for the patient to be able to walk tandem in a straight line. Stance becomes progressively impaired in the more ad-


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vanced cases. Swaying on the Romberg test exceeds the normal 2 cm. The shuffling, small step gait is not the result of rigidity as in parkinsonism or of spasticity but probably is related to instability of stance on one foot and when asked to walk slowly with full steps the patient usually topples. In a few patients gait and posture mimicked parkinsonism (8). Two of our patients not included in the 16 had been treated unsuccessfully for parkinsonism and the error was understandable as the resemblance was indeed close. Posture was stooped, the neck was craned about 6 inches in front of the thoracic convexity, all limb movements were greatly slowed, gait was small-stepped, the arms were not swung and a tendency to forward propulsion was prominent. A patient declared, "If I see an open space I want to propel myself through it." In one of these patients a tremor of the left hand which had been present for about 2 months disappeared after shunting. In patients without shunting, the heels were scuffed in typical parkinsonian style. Rising from a chair was slowed and one patient on rising was sometimes propelled forward into a fall. Another patient in the act of sitting down remained poised 6 inches from the chair while he undertook another task such as lighting a cigarette, putting on a wrist watch, or beginning to eat, unmindful that sitting down had not been completed. When approaching a curb he tended to lift his foot too high and too soon, perhaps 2 or 3 feet before reaching the curb, and would declare, "My timing is off." However, in neither case was cogwheeling present. It is our experience that cogwheeling is more evident when the patient actively flexes and extends his limbs than when they are passively flexed by the examiner and the test should not be interpreted as negative unless active motion has been assessed. Also, the index finger did not become progressively damped on the finger-thumb tapping test. It is to be remarked that most parkinsonian patients maintain a good balance and even in the rather advanced stages, tandem gait may still be possible. On neurological examination, cerebellar ataxia is not present in the legs. On the heel-knee-tibia and shin-tapping tests there is no dysmetria. The plantar responses were both flexor in 7 of the 16 patients, one response was flexor and one extensor in four patients and both responses were extensor in five. The knee and ankle jerks were brisker than in control patients but exceptions occurred and a generalization could not be made. Tone is not increased in patients who are still able to walk. Even in the most severe states spasticity is not prominent. "Gegenhalten" (paratonic rigidity) may mimic rigidity. Sensation in the legs is usually within normal limits. It is obviously easier to say what the gait disturbance is not than what




it is. The mechanism that allows a 6 foot tall human to walk on his two hind legs is imperfect but the nature of the imperfection has yet to be identified.

Disturbance of Mentation As already mentioned, disordered mentation generally appears after the gait disturbance, is relatively less severe and in three cases was not> conspicuous. In the interpretation of hydrocephalic symptoms emphasis which has usually centered on dementia should be shifted or extended to gait disorder. In 8 of the 16 cases the alteration in mentation was mainly in the sphere of memory and could be described as slight to moderate, a change for which the term dementia might be a little too strong. As in dementia of other kinds, a full characterization in neurological terms is still beyond our scope. Impairment of memory is probably the easiest abnormality to detect both in the behavior of the patient in the family circle and in the formal tests of intellectual function. The severity of the deficit ranges widely according to the stage of the hydrocephalic syndrome from a slight limitation on formal testing to an inability to retain one fact for 1 minute associated with ready confabulation. Early in the syndrome the patient often shows a slowing up, a decrease in spontaneity and initiative, a decrease in interest, a diminution in daily accomplishment, a decline in reading, letter-writing, conversation, and hobbies, and the appearance of being depressed. The family may speak of unconcern, a passiveness, apathy, lethargy, and the appearance of being withdrawn. On formal tests of intellectual function, tasks are performed more slowly, attention and concentration are impaired, distractions occur, and there is an inability to maintain a protracted effort. It is said that "mental control" is weak. It may be useful to refer to this complex of abnormalities as the abulic trait or minor abulia. A decrease in attention span becomes evident in testing joint position sense (responses fail after two or three), counting backwards, doing serial subtraction, reciting a prayer, etc. Of 13 patients in whom there were sufficient data, the abulic trait, i.e., a slowing up and lack of interest, was present at an early stage in 11. The neurological nature of this series of behavioral changes and their cerebral localization remain unknown but their close association with disturbance of gait and their gradual evolution or progression into a recognizable abulic syndrome suggest a frontal localization. Since in one case the same symptoms were produced by hydrocephalus resulting from a third ventricular cyst, involvement of structures lying in relation to the lateral ventricle rather than the third ventricle is suggested. Whether


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these disorders reflect derangement of a unitary system or not can only be surmised. Classifying them as an intellectual deficit may not be justified but certainly their effect is to limit or impair performance. On the Bellevue~Wechslertest battery it is almost a rule in symptomatic hydrocephalus that verbal performance is relatively preserved while non-verbal performance is relatively more impaired (drawing, copying, arranging Koh's blocks, puzzle assembly, digit symbol and picture story arrangement). Dyscalculia appears to be the rule. Serial seven subtraction is hampered by the abulic trait as described by one patient, "If I hesitate it is because another irrelevant idea intrudes." Speaking, reading, and writing are usually preserved. As the abulic state (psychomotor retardation, akinetic mutism) advances, hesitation or delay in responding becomes prominent. This trait which we might refer to as "abulic delay" was relatively uncommon in ordinary conversation and was recorded in only 3 of the 16 cases. In the reduced state that may follow pneumoencephalography it is almost always present. In more severe degrees of abulia the patient may fail altogether to respond to questions and commands despite great exhortation by the examiner; or he responds briefly and then enters a refractory period. This on-off phenomenon has been referred to as the "intermittent interruption of behavior" (4). There is an absence of spontaneity and the patient, responding only when addressed, lies silent, often immobile, staring at the examiner, sometimes giving the appearance of hostility. Or he may smile, whistle, or suck his lip. Voluntary movements are slow, delayed, and of small amplitude. The patient is easily distracted by passing sights and sounds. Utterances are brief or interrupted, sentences are not completed and the voice may be reduced to a whisper. It is remarkable that patients with moderate abulia will speak more volubly on the telephone than in personal conversation. For example, one patient who had said not a single word in a week spoke almost normally on the telephone. This behavior, encountered on many occasions, appears to be a reproducible phenomenon and at the Massachusetts General Hospital is referred to as the "Bell effect," after the inventor of the telephone. Food may be held in the mouth for long periods and a morsel of food from one meal may be found in the mouth at the next meal. Feeding the patient seedless grapes may promote swallowing under these circumstances. Accompanying this state of relative akinetic mutism are grasping and sucking reflexes, toe grasp reflexes, sometimes "Gegenhalten" (paratonic rigidity) which may be mistaken for parkinsonian rigidity, inability to walk, stand, or adjust position in bed and incontinence of bladder and bowel. Perseveration and echolalia may be present. The patient may hold one or both arms in the air for




prolonged periods. Deterioration of the patient's condition into the fully developed abulic syndrome can be a complication of pneumoencephalography. In the advanced states of dementia, more complex disturbances may appear. A quiet delirium in which the patient called to absent or dead family members or carried out imaginary manual performances occurred in three patients. Confusion in which the patient talked or acted inappropriately on the basis of disorientation and erroneous imaginary ideas was recorded in five cases. Inappropriate responses to questions and commands occurred in four cases, and nonsensical responses wholly dissociated from the question in two cases. In four cases patients failed to recognize family members. Examples of these disturbances include the following: One patient stated, "What's my name? I don't think names are all that important." Another talked constantly, called out to the nurses, thought the nurse was her daughter, was agitated, had to be restrained, and spoke mostly nonsense: "Day of the week? ... the 10th. Where am I? At Cabot's Ice Cream Store. What's that scar? [cholecystectomy] That was for the blueberries." A third patient insisted on going to the dentist even in the middle of the night and mumbled incoherently. Another was unable to follow commands, was unable to feed himself, and smeared feces over his body and utensils. He said he had seen the house officer in the blacksmith's shop one month before, and gave the name of the President of the United States as Arthur Austin. To the examiner's question, "Who am I?" the response was, "You are Mr. Cobbley's son." When asked to add 2 + 2, he said, "Two plus two can equal into one." "Place?" "Don't ask me." The patient often mumbled unintelligibly. One patient asked wholly inappropriately, "Shall I have the servants take the luggage to the lodge?" Agitation was observed in five cases and mild to moderate belligerency and hostility in six cases. One patient had attacks of anger in which he berated his wife without recalling the event. No spells of rage were encountered similar to those recorded by Crowell and associates in hydrocephalus (3). Excessive jocularity or "witzelsucht" was present in two patients. Sleepiness was a feature in four cases. It should be pointed out that the more serious disturbances of mentation were for the most part limited to the same four cases, while in 9 of the 16 cases no such aberrations occurred at any time. It might be significant that three of the four patients who showed delirium, confusion, and dissociated responses developed the hydrocephalic syndrome over a shorter period of time than most of the others, the evolution of


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symptoms occurring in 1, 2, and 5 months, respectively. This course of events is reminiscent of the subacute hydrocephalic syndrome as it occurs in the several weeks following subarachnoid hemorrhage from ruptured aneurysm. It has been our experience that hydrocephalus is then heralded by the advent of a confused state in a patient who had been progressing satisfactorily. In one of our aneurysm cases the symptomatology in the fully developed state was as florid as that described above. The relatively rapid tempo of the evolution of symptoms appears to influence the clinical picture. These more severe disorders of mentation in symptomatic hydrocephalus were rarely pure states and a mixture of at least two distinct elements was commonly recognizable: the abulic syndrome and the delirium-confusion syndrome.

Incontinence of Sphincters Urinary incontinence was a feature of 10 of the 16 cases when the hydrocephalus was first diagnosed. In only three cases was it characterized as an urgency, while in the others it was of the frontal lobe type in which appropriate concern is lacking or diminished and wetting may occur in front of other people without embarrassment. The patient may appear to be unaware of the lapse. Incontinence of bowel is less common and is of the same type. In the advanced abulic state incontinence of both sphincters regularly occurs. Rectal flatus may be expelled immodestly. Incontinence if it occurs is almost always a later development than gait disturbance and impaired mentation and appears only when gait and mentation are obviously disturbed. In no case was it an early sign.

Other Attributes of the Hydrocephalic Syndrome FALLING SPELLS OF UNCONSCIOUSNESS, FAINTNESS OR WEAKNESS

Convulsive seizures of undetermined origin occurred in two cases before shunting or any other cranial surgery. Old cranial trauma may have been a factor but seizures cannot be wholly excluded as an occasional sequela of hydrocephalus. As already mentioned, five patients were subject to falls from which they could not arise for 2 to 6 hours. These spells were akinetic or nonconvulsive and adequate descriptions are rare. Two patients may have been briefly out of touch. There appear therefore to be three different types of falling spells - true seizures, prolonged falls, and slumping spells in which the patient is probably briefly unconscious. Tremor of the hands during action was present in two patients. It involved the fingers and had an amplitude of a few millimeters. In two




other cases not included in this series a unilateral tremor was relieved by shunting. More precise observations on the nature of the tremor and its response to shunting are in order. One of Dr. Salomon Hakim's patients made the interesting observation that after shunting, her ability to shed tears was restored. However, other patients have cried easily before surgical relief. One of our patients showed pseudobulbar laughing and crying. Another made very loud sucking sounds with his lips that could be heard several rooms away. Paresis of upward gaze, convergence spasm, lid retraction, and nystagmus retractorius which may occur in acute high pressure hydrocephalus were not seen in our cases (2); neither was failure of the thirst mechanism. At the same time as the positive findings are being enumerated, it may be well to underline some of the negative aspects. In the normal pressure hydrocephalic syndrome there are no focal signs and no lateralizing signs. Conspicuously absent are headache, dysarthria, numbness, paralysis, aphasia, cerebellar dysmetria in the limbs, papilledema, depression, hallucinations, and paranoia. Postlumbar puncture headache does not occur.

Other Characteristics of Symptomatic Hydrocephalus 1. The syndrome is progressive and the tempo of evolution is highly variable. The period from the onset of gait disturbance to surgical operation in the 16 cases was: 3 weeks, 1 month, 3 months, 4 months, 6 months, (four cases), 2 years (two cases), 4 years (four cases), 6 years, and 20 years. In four of the cases of shorter duration a fall with head trauma may have been a factor in precipitating the syndrome and in one a cerebrovascular stroke of undetermined origin seemed to have been the trigger. The longest periods between the appearance of gait disturbance and change in mentation were 8 months, 2 years, 3 years, 6 years, and 19 years. Usually it was much shorter. 2. A history of fluctuating symptoms is not uncommon. 3. Improvement after lumbar puncture was striking in three cases and definite but less marked in several others. In one patient almost complete recovery occurred after 8 days with the CSF pressure atmospheric although the ventricular size determined on computerized tomography (CT) scanning had remained unchanged. 4. Abrupt deterioration in the patient's condition following pneumoencephalography is a well-recognized phenomenon and can be avoided by using oxygen in limited amounts. CLINICAL TYPES OF HYDROCEPHALUS

The various ways in which hydrocephalus can present may be listed as follows:


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1. Normal pressure hydrocephalic syndrome a. Typical b. Delirium-confusional state c. Parkinson-like d. Hostility and anger e. Gait disturbance only 2. Associated with other neurologic diseases-tumor, cyst, meningitis, Arnold-Chiari, etc. 3. Subacute syndrome after subarachnoid hemorrhage and trauma 4. In combination with dementia of another type 5. Acute superimposed increased CSF pressure 6. Asymptomatic, arrested, or compensated 7. Asymptomatic complicating other illness 8. Unilateral hydrocephalus 9. Symptomatic local or porencephalic hydrocephalus 10. After anoxia 11. Symptomatic elevated pressure hydrocephalus (papilledema). A few of these need further comment.

Acute Superimposed Increased CSF Pressure A pre-existing chronic asymptomatic hydrocephalus may become symptomatic acutely when the intracranial pressure is abruptly elevated by the superimposition of another intracranial disease processruptured saccular aneurysm, hemorrhage into tumor, hypertensive cerebellar hemorrhage, meningeal carcinomatosis, etc. The rapid increase in pressure precipitates a comatose-stuporous state whose interpretation can be puzzling. Asymptomatic Hydrocephalus With a ventricular span of 60 to 80 mm., hydrocephalus not infrequently is asymptomatic and this possibility must be kept in mind. Whether the process is still evolving or has become arrested will require further observations. Symptomatic hydroporencephaly in which a progressive local hydrocephalus evolves to the accompaniment of symptoms appears to be rare but with the common use of CT scanning further cases will no doubt come to light. After severe cerebral anoxia with long survival a progressive enlargement of the ventricle occurs with the ventricular span reaching as much as 110 mm. THE DIFFERENTIAL DIAGNOSIS-PARTICULARLY OF HYDROCEPHALIC DEMENTIA

The detection of hydrocephalus has been immeasurably facilitated and simplified by the introduction of CT scanning. In the future all




patients with a neurologic complaint, particularly ifit is obscure, will be scanned as part of the routine investigation and the formerly vexing decision whether pneumoencephalography and angiography are warranted will be avoided. Since hydrocephalus is always a secondary disorder, the first task is to undertake a search for the site and cause of the obstruction in the CSF pathways using pneumoencephalography if necessary. Rarely, a papilloma of the choroid plexus will be responsible. With easier CT diagnosis of hydrocephalus the main clinical problem to be resolved will be whether the hydrocephalus accounts for the patient's symptoms. Since the earliest symptomatology of hydrocephalus usually pertains to imbalance in gait and stance, hydrocephalus must be considered as a factor in cases of imbalance of obscure nature, particularly when the clinical characteristics are those of hydrocephalic ataxia. Concerning dementia, if the rules are correct, only those cases in which dementia is preceded by or accompanied by a disturbance of gait and stance need to be considered as candidates for the diagnosis of hydrocephalic dementia. A review of 25 consecutive personal cases of dementia presumed to be Alzheimer's disease showed that none had a hydrocephalic disturbance of gait, an indication that Alzheimer's disease can usually be distinguished from the hydrocephalic syndrome on clinical grounds. Whereas senile dementia or dotage may start with a memory disorder that mimics hydrocephalic dementia, presenile dementia, beginning in the 50's and early 60's, is soon accompanied by dominant and non-dominant hemispheral deficits which result in a pattern of dementia which has not been described so far in hydrocephalus. The severe memory loss so common in Alzheimer's disease is seen in hydrocephalus only when walking is virtually impossible. Also, urinary incontinence is usually a late development in Alzheimer's disease. There is a small group of Alzheimer's cases in which a disturbance of gait parallels the progression of the dementia but such cases have not been well documented either clinically or pathologically. One of our failure cases was probably of this type and although the patient walked with a short step shuffling gait, he had never fallen and the dementia was greatly out of proportion to imbalance. No doubt a small step shuffling gait is the end product of several different processes and by no means is specific for hydrocephalus. Occasionally a case of dementia, for example, Alzheimer's disease, will become complicated by the unrelated development of hydrocephalus and shunting will delay the new manifestations but will not influence the original dementia. There are cases of presumed Alzheimer's disease in which ventricular enlargement is so great as to suggest obstructive hydrocephalus. The majority of our failure cases were of this type. One patient with a typical


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Alzheimer's dementia of advanced degree (mentation 0/10) showed a ventricular span of77 mm. and convexity air. However, there was little or no disturbance of gait and shunting was ineffective. Five cases with dementia first and foremost and a ventricular span of 58 to 68 mm. were failures, as were four cases with a ventricular span of less than 50 mm. In our failure cases, pneumoencephalography showed convexity air in five cases, none in four cases, and Sylvian air in one. The mechanism of ventricular enlargement in brain atrophy, i.e., shrinkage vs. distention, or a combination of the two, the changes of ventricular size with age, and the comparative topographic details of hydrocephalic and atrophic enlargement have yet to be clarified (6). Hydrocephalic dementia has to be distinguished from the dementias of other causes that may be accompanied by impaired locomotionPick's disease, supranuclear palsy, cerebellar degeneration, the lacunar state, akinetic parkinsonism with dementia, thiazine toxicity, drug intoxication, multiple sclerosis, traumatic encephalopathy, and hypoand hyperthyroidism. At the age of 70 memory and gait are apt to be less than perfect. Dementia complicated by the various unrelated infirmities of age that lead to deterioration of locomotion will have to be distinguished. Chronic alcoholism may predispose to the development of hydrocephalic symptoms and may have been a factor in 2 of the 16 cases in the present series (5). It is our experience that unless the ventricular span is greater than 53 mm. in the pneumogram, shunting will fail to alleviate chronic symptoms. Lesser ventricular enlargement is probably tolerated and asymptomatic when the pressure is normal. The ventricular span in the 16 cases was between 59 and 88 mm. The factor for converting CT scan measurement to PEG is 4. A resting CSF pressure of less than 100 mm. also is an indication that shunting will fail. It was more than 110 mm. in all 16 cases. Symptoms present more than 3 or 4 years may not be reversed suggesting that permanent damage has occurred. For some reason shunting seemingly excellent candidates is more regularly attended by success when the patient is younger rather than over the age of 65. There was air in the Sylvian fissure and/or in the callosal or callosomarginal sulci in 6 of the 16 cases. The electroencephalogram showed intermittent slow-wave activity in 14 of the 16 cases. In two it was normal. SUMMARY

From a study of 16 successfully shunted cases of symptomatic normal pressure hydrocephalus, the typical symptomatology has been characterized. It was found that gait disturbance preceded impaired mentation in 12 of the 16 cases, it began at the same time in three cases and in only




one case did impairment of mentation precede it. Of 11 cases of shunt failure, dementia came first in nine and the disturbance of locomotion was relatively less severe or was absent. The various ways in which hydrocephalus may present have been outlined. REFERENCES 1. Adams, R. D., Fisher, C. M., Hakim, S., Ojemann, R. G., and Sweet, W. H.

2.

3.

4. 5.

6. 7.

8.

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Occult normal pressure hydrocephalus with parkinsonian symptomatology.

The clinical picture.

[The clinical picture and therapy of vitiligo].

The complex clinical picture of benzodiazepine misuse.

The clinical significance of occult HBV infection.

The iceberg: 'completing the clinical picture' in general practice. 1963.

Mallory-Weiss syndrome. A changing clinical picture.

[The Verner-Morrison syndrome. The clinical picture and pathologic anatomy].

Hemoglobin Potomac: clinical picture, biosynthesis and stability.

Cobalamin deficiency: clinical picture and radiological findings.

Clinical picture of peptic ulceration diagnosed endoscopically.

[The clinical picture of neurosarcoidosis. The MR tomographic follow-up].

Prevalence and clinical picture of musculoskeletal sarcoidosis.

[Morphology and clinical picture of thymus carcinoid].

[The clinical picture and therapy of progressive systemic scleroderma].

[The clinical picture and diagnosis of perioperative delirium tremens].

[The clinical picture and therapy of Hantaan virus infection].

The changing clinical picture and epidemiology of spondyloarthritis.

[The clinical picture and diagnosis of pulmonary mycoses].

The clinical problem of occult cardiac amyloidosis. Forensic implications.

Anatomo-clinical correlations in normotensive hydrocephalus. Reports on three cases.

Multiple familial pilomatrixomas in three generations: an unusual clinical picture.

Clinical picture of endemic cretinism in central Apennines (Montefeltro).

Prevalence and clinical picture of IDDM in Nigerian Igbo schoolchildren.