The findings from the new neurological examination were again essentially within normal limits, except for a "questionable left visual field defect." However, the neurologist noted a peculiarity when the patient was asked to copy a standard clock face placed in front of her: she copied only the numbers 12 to 6, which were crowded into the right half of her drawing. The left side of the clock face (with numbers 7 to 11) was blank.
ConsultantThat is very worrisome. This is likely to be an example of hemispatial neglect. A person who has damage to the right parietal lobe will not attend to things in the left visual field. For example, a person may not shave the left side of his face. Or, a patient with a right parietal stroke may bump into things on the left side when walking. I now believe the EEG and the MRI findings will be especially important.
CASE VIGNETTEFindings from a repeated waking EEG with nasopharyngeal leads was again normal. However, prolonged (72 hour) 16-channel ambulatory EEG monitoring coincided with one of the patient's typical panic episodes, which evolved into a period of altered consciousness. This coincided with abnormal spike discharges in the right parietal region, without accompanying discharges in mesial temporal regions.
T2-weighted imaging on the MRI scan showed a 2.1 3 2.3-cm mass in the right parietal lobe. Subtotal resection and pathological examination revealed a low-grade astrocytoma. The patient's subsequent 3-month course showed a near-total disappearance of panic episodes and altered level of consciousness.
DiscussionThe association between panic symptoms and CPS has been known for many years, but the precise nature of this association is complex.2,3 On the one hand, CPS, usually originating in the temporal lobe, may produce symptoms that closely mimic those of a panic episode, such as paresthesias, anxiety, and tachycardia.
Indeed, a wide range of psychiatric symptoms are associated with CPS, including poor impulse control, rage episodes, suicide attempts, rapid mood swings, depression, and psychotic episodes.3 On the other hand, patients whose panic episodes lead to severe hyperventilation may actually develop neurological symptoms, such as paresthesias and altered levels of consciousness.4
The differential diagnosis of these two conditions can be difficult, and some patients may meet criteria for both PD and CPS. Although CPS-related anxiety is commonly associated with seizure foci in the temporal lobes, evidence suggests that parietal lobe seizures (PLS) may present with panic episodes. At least two cases of PLS- related panic episodes due to underlying parietal lobe tumors have been reported.5 Strikingly, results of the neurological examinations in both cases were reported as "unremarkable," as were initial standard lead EEG recordings.
In the composite case described here, an important (although long-delayed) clue was the presence of hemispatial neglect—a hallmark of right parietal lobe pathology.6 It is intriguing that some patients with right parietal seizure foci can present a transient neglect phenomenon in the postictal period, even in the absence of overt clinical neglect signs.7
Although late age at onset of panic episodes (after age 45) may help point to the presence of a structural/neurological cause, age of onset was clearly not helpful in this case. However, the alteration in level of consciousness—not seen in most patients with PD—was an important clue.
Aside from the specific pathology in this case, there are cautionary take-home lessons for all psychiatrists. First, a neurological examination may be unremarkable or nonfocal, even in the presence of structural brain disease. Second, routine EEGs may also be normal, even when epilepsy is present. (Repeated EEGs with nasopharyngeal leads or prolonged ambulatory monitoring is often necessary to "catch" the seizure.) Third, a favorable response to psychotropic medication (at least initially) is not unequivocal evidence of a psychogenic cause; on the contrary, a favorable response may also be seen when the psychopathology is due to underlying structural brain disease or epilepsy. Finally, psychiatrists must always look beyond DSM-IV criteria and scrutinize the longitudinal course and evolution of a psychiatric disorder—for example, noting that alteration in consciousness was not an early feature in this case, but developed, presumably, as the underlying tumor expanded.
The title of this column—"Up Against the Wall"—is derived from the word "parietal," ie, from the Latin "parietalis," meaning "belonging to the wall." The idea is that the parietal lobe rests directly against the "wall" of the skull; hence, expansion of a parietal tumor can go on just so long before the patient begins to suffer.
