Cablevision Systems Corp., yesterday reported revenues grew 11% in the first nine months of 1992, but also reported a higher loss per share when compared to the same period a year ago.Cablevision reported a net loss of $ 184,604,000 ($ 8.23 per share) on revenues of $ 414,947,000 for the nine-month period ending Sept. 30, vs. a $ 161 ,289,000 ($ 7.23) loss on revs of $ 375,141,000 reported for the same period in 1991. For the quarter, the company posted a net loss of $ 45,592,000 ($ 2.05) on revenues of $ 151,278,000 against a loss of $ 51,655,000 ($ 2.32) on revenues of $ 127,565,000 reported for the third quarter in 1991. Cablevision, which serves 1.2 million cable homes in 19 states, attributed its revenue increase to internal growth in subscribers, rate increases and the completed acquisition of the piece of Cablevision of New York City that it did not previously own. Operating cash flow at the company increased 18% in the third quarter to $ 63 ,735,000 when compared to $ 54,069,000 generated in the quarter last year. Cash flow for the nine-month session was up 13% to $ 181,304,00. Cablevision’s acquisition of CNYC accounted for 5% of the cash-flow boost in the third quarter and 2% of the nine-month growth. Interest expenses for the third quarter were $ 50,047,000, up from $ 47,084, 000 for the same period last year. Interest expenses in the first nine months were $ 143,692,00, up from $ 140,928,00 in the comparable period in 1991. Cablevision said the increases in interest expenses resulted from the inclusion of CNYC debt and from its issuance of $ 275 million 10 3/4% senior subordinated debentures in April.